Learning Objectives
Chapter Overview
Key skills you will develop by the end of Chapter 5: Periodic Table.
State what the periodic table is and how elements are arranged by atomic number
Define atomic number and write the electron arrangement of the first 18 elements
Explain what a period is and how atomic number and reactivity change across it
Describe Groups I–VIII — alkali metals, halogens, noble gases — and their reactivity trends
Describe the properties of metals and non-metals, and identify metalloids like silicon
Give the everyday uses of common metals: iron, aluminium, copper, lead, tungsten, brass and steel
Answer board-style MCQs, true/false, data and periodic-table questions accurately
General Science: Periodic Table
Complete chapter notes: atomic number, electron arrangement, periods, groups, metals and non-metals, plus the full board exercise — PDF format
How to use these notes: Every concept is turned into exam questions below, each written in several ways (the different phrasings your board or teacher might use). Tap a question, try it in your own words, then check the answer. If you can answer every phrasing, you have learned the concept. Download the PDF for a printable copy.
Core Notes · Part 1
The Periodic Table & Atomic Number
What the table is, and what the atomic number tells you.
The Periodic Table & Atomic Number
Tip: Atomic number = the number of PROTONS in an atom. Elements are placed in order of increasing atomic number.
Common Mistake: Atomic number is protons ONLY — it is NOT protons + electrons, and NOT protons + neutrons (that sum is the mass number).
1. What is the periodic table?
• Define the periodic table.• How would you describe what the periodic table is?
The periodic table is a system (an organised chart) for arranging all the chemical elements. In it, elements are listed according to the structure of their atoms — mainly the number of protons and the number of electrons in their outer shell.
2. On what basis are elements arranged in the periodic table?
• According to what are elements listed in the periodic table?• What decides an element’s position in the periodic table?
Elements are arranged according to the structure of their atoms — the number of protons (the atomic number) and the number of outer-shell electrons. They are listed in order of increasing atomic number.
3. What is the atomic number of an element?
• Define atomic number.• What is meant by the atomic number of an atom?
The atomic number is the number of protons in an atom. Every element has its own atomic number, and elements are placed in the periodic table in order of increasing atomic number.
4. How is the atomic number related to the number of protons?
• If an atom has 11 protons, what is its atomic number?• What does the atomic number tell you about the protons?
The atomic number equals the number of protons in the atom. So an atom with 11 protons has atomic number 11 (that element is sodium).
5. In a neutral atom, how does the number of electrons compare with the number of protons?
• How many electrons does a neutral atom of atomic number 17 have?• Why does the number of electrons equal the atomic number in a neutral atom?
In a neutral atom the number of electrons equals the number of protons (the atomic number). So an atom of atomic number 17 (chlorine) has 17 electrons, arranged 2,8,7.
6. What information is given for each element in the periodic table (the key)?
• What do the numbers and symbol around an element’s box mean?• What does each element’s box in the periodic table show?
Each element’s box shows its atomic number, its chemical symbol, its name and its mass number. The atomic number identifies the element and fixes its position.
7. Why is it useful to arrange elements in the periodic table?
• What is the benefit of grouping elements with similar properties together?• How does the periodic table help us understand elements?
Arranging elements by atomic number and outer electrons puts elements with similar properties together. This lets us predict how an element behaves from its position — its group tells us its reactivity and whether it is a metal or a non-metal.
Core Notes · Part 2
Electron Arrangement
How electrons fill the shells, and the arrangement of key elements.
Electron Arrangement of the First 18 Elements
Tip: To write any arrangement, fill the shells from the inside out: up to 2 in the 1st shell, up to 8 in the 2nd, then up to 8 in the 3rd (stable).
Note: The shells are named K (1st), L (2nd) and M (3rd). K holds 2, L holds 8, M can hold 18 but is stable at 8.
8. What is meant by the electron arrangement (configuration) of an atom?
• What does the electron configuration of an element tell you?• What is electron arrangement?
The electron arrangement (or configuration) shows how the electrons are shared out among the shells, written from the innermost shell outwards, e.g. sodium is 2,8,1. It tells you how many electrons are in each shell — especially the outer shell.
9. How many electrons can the first, second and third shells hold?
• What is the maximum number of electrons in the K, L and M shells?• State the electron capacity of the first three shells.
The first shell (K) holds up to 2 electrons, the second shell (L) up to 8, and the third shell (M) can hold up to 18 but is stable when it has 8. Shells fill from the inside outwards.
10. The third shell (M) can hold up to 18 electrons but is said to be stable at 8. What does this mean?
• Why is the M shell considered stable with only 8 electrons even though it can hold 18?• Explain the statement that the third shell is “stable at 8.”
It means that once the third shell has 8 electrons, the atom has a stable, noble-gas-like arrangement (like argon, 2,8,8) and behaves as if its outer shell is full — so it is stable and unreactive. This is why argon does not react (the octet rule: 8 outer electrons = stable).
11. Which shell fills with electrons first?
• In what order are the electron shells filled?• Do electrons fill the inner shell or the outer shell first?
Electrons fill the innermost shell first. The first shell fills (up to 2), then the second (up to 8), then the third — always from the inside outwards.
12. How do you work out the electron arrangement of an element from its atomic number?
• How can you use the atomic number to write an element’s electron configuration?• Explain how to fill the shells to find an element’s electron arrangement.
The atomic number gives the total number of electrons. Fill the shells from the inside out: 2 in the first, 8 in the second, then 8 in the third. For example chlorine (17) fills as 2, then 8, then 7 → 2,8,7.
13. What is the electron arrangement of lithium?
• Write the electron configuration of lithium (atomic number 3).• How are the electrons of a lithium atom arranged in its shells?
Lithium (atomic number 3) has the arrangement 2,1 — two electrons in the first shell and one in the outer (second) shell.
14. What is the electron arrangement of oxygen?
• Write the electron configuration of oxygen (atomic number 8).• How are the 8 electrons of oxygen arranged in shells?
Oxygen (atomic number 8) has the arrangement 2,6 — two electrons in the first shell and six in the outer (second) shell.
15. What is the electron arrangement of aluminium?
• Write the electron configuration of aluminium (atomic number 13).• How are aluminium’s 13 electrons arranged in its shells?
Aluminium (atomic number 13) has the arrangement 2,8,3 — two in the first shell, eight in the second, and three in the outer (third) shell.
16. What is the electron arrangement of argon?
• Write the electron configuration of argon (atomic number 18).• How are argon’s electrons arranged, and why is it stable?
Argon (atomic number 18) has the arrangement 2,8,8. Its outer shell holds 8 electrons — a full, stable arrangement — which is why argon is unreactive (a noble gas).
17. What is the electron configuration of sulphur?
• Write the electron arrangement of sulphur (atomic number 16).• How are the 16 electrons of a sulphur atom shared among the shells?
Sulphur (atomic number 16) has the configuration 2,8,6 — two in the first shell, eight in the second, and six in the outer shell. (So in the MCQ the correct option is 2,8,6.)
18. What is the electron arrangement of sodium?
• Write the electron configuration of sodium (atomic number 11).• How are sodium’s electrons arranged in shells?
Sodium (atomic number 11) has the arrangement 2,8,1 — two in the first shell, eight in the second, and one in the outer shell. Having 1 outer electron places it in Group I and makes it very reactive.
19. What is the electron arrangement of magnesium?
• Write the electron configuration of magnesium (atomic number 12).• How are the electrons of a magnesium atom arranged?
Magnesium (atomic number 12) has the arrangement 2,8,2 — two in the first shell, eight in the second, and two in the outer shell (so it is in Group II).
20. What is the electron arrangement of neon, and why is it unreactive?
• Write the electron configuration of neon (atomic number 10) and explain its stability.• Why does neon (2,8) not react?
Neon (atomic number 10) has the arrangement 2,8 — its outer shell is full with 8 electrons. Because the outer shell is complete, neon is stable and does not react (it is a noble gas).
21. Why is helium unreactive even though its outer shell holds only 2 electrons?
• How can helium be stable with just 2 outer electrons?• Explain helium’s stability.
Helium’s only shell is the first shell, which is full with 2 electrons. A full outer shell makes helium stable and unreactive, so it is a noble gas.
22. Why is the number of outer-shell electrons so important?
• What do the outer electrons decide about an element?• Why do we focus on the outer shell when grouping elements?
The number of outer-shell electrons decides how an element reacts and which group it belongs to. Elements with the same number of outer electrons react similarly, so they are placed in the same group.
Core Notes · Part 3
Periods — the Rows
Rows of the table and how atomic number and reactivity change across them.
Periods (the Horizontal Rows)
Tip: A PERIOD is a ROW. You read it left → right, and the atomic number goes up by 1 at each step.
23. What is a period in the periodic table?
• Define a period.• What is meant by a period in the periodic table?
A period is a horizontal row in the periodic table. The rows are arranged on top of each other, and within a period the elements are placed from left to right in order of increasing atomic number.
24. Describe how the atomic number changes as you move across a period from left to right.
• In what order are elements placed across a period?• What happens to the atomic number across a period?
Across a period from left to right, the atomic number increases — it goes up by one from each element to the next.
25. Why is the first period described as very short?
• How many elements does the first period contain, and which are they?• What is special about the first period?
The first period is very short because it contains only two elements — hydrogen and helium.
26. How many elements are in the sixth period?
• State the number of elements in period 6.• Which period contains 32 elements?
The sixth period contains 32 elements (it is one of the longest periods).
27. What can you say about the element at the start (left-hand end) of a period?
• Describe the outer-shell electrons and reactivity of the first element in a period.• Why is the element at the left-hand end of a period very reactive?
The element at the start (left-hand end) of a period has only 1 electron in its outer shell and is very reactive.
28. What can you say about the element at the end (right-hand end) of a period?
• Describe the outer shell and reactivity of the last element in a period.• Why is the element at the right-hand end of a period unreactive?
The element at the end (right-hand end) of a period has a full outer shell. Elements with full outer shells are very unreactive.
29. Why do elements in the same vertical column have similar properties?
• When elements are lined up by atomic number in periods, why are those in the same column alike?• What makes the elements in one column behave alike?
When elements are lined up in periods by atomic number, elements in the same vertical column end up with the same number of outer-shell electrons, so they have similar properties.
30. Compare the left and right ends of a period for reactivity.
• Which end of a period has a very reactive element with 1 outer electron?• Where in a period is the reactive metal and where is the unreactive element?
The left-hand end of a period has a very reactive metal with 1 outer electron (Group I). The right-hand end has an element with a full outer shell that is very unreactive (a noble gas).
Core Notes · Part 4
Groups & Element Families
Columns of the table: alkali metals, halogens, noble gases and more.
Groups (the Columns) & the Element Families
Tip: GROUP number = number of OUTER-shell electrons. Group I = 1 outer electron, Group II = 2, … Group VII = 7.
Common Mistake: Reactivity increases DOWN the metal groups (I and II) but increases UP the halogens (Group VII). The two trends are OPPOSITE.
31. What is a group in the periodic table?
• Define a group.• What are the vertical columns of the periodic table called?
A group is a vertical column in the periodic table. All the elements in a group have the same number of electrons in their outer shell.
32. Why do all the elements in a group behave in a similar way during chemical reactions?
• Why do members of the same group react similarly?• What causes elements in the same group to have similar chemical behaviour?
Because all the elements in a group have the same number of outer-shell electrons, they behave in a similar way during chemical reactions (chemical behaviour depends mainly on the outer electrons).
33. How are the groups numbered in the periodic table?
• What decides a group’s number?• On what basis are groups given their numbers?
Groups are numbered according to the number of electrons in the outer shell of their elements. For example, Group I elements have 1 outer electron and Group II have 2.
34. What is the name of Group I, and what property do all its elements share?
• Describe Group I of the periodic table.• What are the alkali metals and how many outer electrons do they have?
Group I is the alkali metals. All alkali metals have one electron in their outer shell and are very reactive.
35. How does reactivity change down Group I?
• Are alkali metals at the top or bottom of the group more reactive?• Describe the reactivity trend in the alkali metals.
In Group I, reactivity increases lower down the group — elements at the bottom are more reactive than those at the top.
36. Describe how potassium reacts with water.
• What kind of metal is potassium and how does it behave with water?• Why does potassium react violently with water?
Potassium is a soft metal that reacts violently with water. It is an alkali metal (Group I), and because reactivity increases down the group, potassium is more reactive than the lithium and sodium above it.
37. What does it tell us that potassium is described as a “soft” metal?
• Are alkali metals hard or soft?• Describe the hardness of Group I metals like potassium.
Alkali metals such as potassium are soft (potassium can be described as a soft metal), unlike most other metals which are hard. They are also very reactive, especially with water.
38. What is the name of Group II and how many outer electrons do its elements have?
• Describe Group II of the periodic table.• What are the alkaline earth metals?
Group II is the alkaline earth metals. All its elements have two electrons in their outer shell. Like Group I, their reactivity increases lower down the group.
39. How does magnesium react with cold water and with steam?
• Compare magnesium’s reaction with cold water and steam, and why is it used in fireworks?• Why is magnesium used in fireworks and flares?
Magnesium reacts quite slowly with cold water but more quickly with steam. It is used in some fireworks and flares because it burns in air with a very bright light.
40. Describe Group III of the periodic table.
• How many outer electrons do Group III elements have, and are they metals or non-metals?• What happens to the metallic character down Group III?
Group III elements have three electrons in their outer shell. At the top of the group is a non-metal, but lower down the elements become metallic.
41. What is Group IV called and how many outer electrons do its elements have?
• Describe the carbon family.• How does metallic character change down Group IV?
Group IV is the carbon family. All its elements have 4 electrons in their outer shell. Non-metals are at the top and metallic elements are lower down.
42. What is Group V called and how many outer electrons do its elements have?
• Describe the nitrogen family.• How does metallic character change down Group V?
Group V is the nitrogen family. All its elements have 5 electrons in their outer shell, and the elements get more metallic lower down the group.
43. What is Group VI called and how many outer electrons do its elements have?
• Describe the oxygen and sulphur family.• Are Group VI elements mostly metals or non-metals?
Group VI is the oxygen and sulphur family. All its elements have 6 electrons in their outer shell. They are mainly non-metals, with some metallic elements lower down the group.
44. What is Group VII called, and why are its elements very reactive?
• Describe the halogens.• Why do halogen atoms react so readily?
Group VII is the halogens. They are very reactive because their atoms have 7 outer electrons — just one empty space in the outer shell — so they easily gain an electron. Halogens are coloured gases and very poisonous.
45. How does reactivity change down Group VII (the halogens)?
• Are halogens more reactive at the top or bottom of the group?• Describe the reactivity trend in the halogens.
In the halogens, elements at the top of the group are more reactive than those at the bottom — so reactivity decreases down the group (the opposite of the metal groups).
46. What does the chapter tell us about the appearance and danger of halogens?
• Are halogens coloured or colourless, and are they safe?• Describe the halogens as a group.
Halogens are coloured gases and are very poisonous. They are also very reactive because their atoms have one empty space in the outer shell.
47. Bromine is a red liquid — what happens to it when it turns into a gas?
• What colour is bromine as a liquid and as a gas?• Describe the change in bromine from liquid to gas.
Bromine is a harmful red liquid (a halogen) that readily turns into a brown gas — the textbook describes this as “subliming” into a brown gas.
48. What harm do some halogen compounds such as CFCs cause?
• How do CFCs damage the environment?• Why are CFCs (chlorofluorocarbons) dangerous to the ozone layer?
Some halogen compounds damage the environment. CFCs (chlorofluorocarbons) break down the ozone layer, which protects us from the Sun’s harmful ultraviolet radiation.
49. Even though halogens have few uses, what important use does chlorine have?
• Why is chlorine added to drinking water?• What property of chlorine makes it useful for water treatment?
Because of their high reactivity, halogens have few uses — but chlorine is an exception. Its disinfecting properties are used when it is added in small quantities to drinking water.
50. Household bleach contains a chlorine compound — what is it called?
• Which chlorine compound is found in household bleaches?• Name the chlorine-containing chemical in bleach.
Household bleaches usually contain a compound of chlorine called sodium hypochlorite.
51. What is Group VIII (Group 0) called, and why don’t its elements react?
• Describe the noble gases.• Why are noble gases unreactive?
Group VIII (also called Group 0) is the noble gases. They are famous because they do not react — this is because their outer electron shells are completely full, which makes them stable.
52. Why is helium used in balloons?
• What properties make helium suitable for balloons?• Give the uses/properties of helium.
Helium is safe (unreactive) and much lighter than air, so it is used to fill balloons.
53. Why is a noble gas like helium safer than a reactive gas for filling balloons?
• What makes noble gases suitable for uses where reactivity would be dangerous?• Explain why helium is preferred over a reactive gas in balloons.
Noble gases do not react (their outer shells are full), so helium will not burn or explode. Being unreactive and lighter than air makes it a safe choice for balloons.
54. Why are elements with a nearly-empty or nearly-full outer shell very reactive?
• Why are Group I and Group VII elements both very reactive?• Link an element’s reactivity to the number of outer electrons.
Elements react to reach a stable, full outer shell. Group I atoms have just 1 outer electron to lose, and Group VII atoms need just 1 electron to fill the shell — both are close to a stable arrangement, so both are very reactive. Noble gases already have full outer shells, so they are unreactive.
Core Notes · Part 5
Metals, Non-metals & Metalloids
Properties of metals and non-metals, and the everyday uses of common metals.
Metals, Non-metals & Metalloids and Their Uses
Tip: Learn these three words: Malleable = hammered into shape; Ductile = pulled into wires; Sonorous = rings when hit.
Note: A stepped (zig-zag) line divides metals (left) from non-metals (right). Silicon, sitting on the line, is a metalloid (semi-metal).
55. What does the stepped line on the periodic table separate?
• How are metals and non-metals arranged on the periodic table?• Where are the metals and non-metals found on the periodic table?
A stepped (zig-zag) line divides the metals from the non-metals. Metals are on the left of the line and non-metals are on the right.
56. List the general properties of most metals.
• What physical properties do most metals have?• How can you describe a typical metal?
Most metals are naturally shiny (lustrous), can be hammered into shape (malleable), can be pulled into wires (ductile), make a ringing sound when hit (sonorous), are good conductors of heat and electricity, are strong, and have high melting and boiling points.
57. What does “malleable” mean, and give an example?
• Which metal is malleable enough to be used for waterproofing roofs?• Explain the property that lets lead be bent into shape for roofs.
Malleable means a material can be hammered or bent into shape without breaking. Lead is malleable enough to be bent into shape to waterproof roofs.
58. What does “ductile” mean, and give an example?
• Which metal is ductile and pulled into thin wires for light bulbs?• Explain why tungsten can be drawn into wire.
Ductile means a material can be pulled (drawn) into wires. Tungsten is a ductile metal that is pulled into thin wires for use in light bulbs.
59. Why does the tungsten wire in a light bulb glow?
• What property of tungsten makes the bulb filament glow?• Explain how tungsten produces light in a bulb.
Tungsten has high resistance, so its thin wire glows (gives out light) when an electric current passes through it. Being ductile also lets it be made into thin filaments.
60. What does “sonorous” mean, and give an example?
• Why are some musical instruments and bells made of brass?• What property of brass makes a bell ring loudly?
Sonorous means a material makes a ringing sound when it is hit. Brass is a sonorous alloy, so it is used for bells and musical instruments — a brass bell makes a loud sound when rung.
61. What is brass made from?
• Which two metals are mixed to make brass?• Name the alloy made from copper and zinc.
Brass is an alloy made from copper and zinc. It is sonorous, which is why it is used for musical instruments and bells.
62. What is steel, and why is it used in vehicle engines?
• Which alloy is used to make engines because it withstands high temperatures?• Describe steel and one of its uses.
Steel is an alloy of iron. It is used to make vehicle engines because it can withstand the very high temperatures generated inside an engine when it is running.
63. What properties would you use to describe steel?
• Describe the useful properties of steel.• Why is steel a good material for engines and buildings?
Steel is strong, hard and can withstand very high temperatures. It is an alloy of iron, which makes it stronger than iron alone, so it is used for engines, bridges and buildings.
64. Why is iron used to build bridges?
• What property of iron makes it good for construction?• Give a use of iron and the reason for it.
Iron is used in the construction of bridges because it is strong.
65. Why is aluminium used to make saucepans and cooking utensils?
• What property of aluminium makes it good for cookware?• Give a use of aluminium based on its ability to conduct heat.
Aluminium is a good conductor of heat, which makes it ideal for making saucepans and other cooking utensils.
66. Why is aluminium used to make overhead electricity cables?
• What property of aluminium suits it to power cables?• Give a use of aluminium apart from cookware.
Aluminium is used to make overhead electricity cables because it is a good conductor of electricity and is light in weight.
67. Why is copper wire used in electrical circuits?
• What property of copper makes it suitable for electrical wiring?• Explain the use of copper in circuits.
Copper is used for wires in electrical circuits because it is a very good conductor of electricity (and being ductile, it can be drawn into wires).
68. What properties would you use to describe gold?
• Why is gold suitable for jewellery, and what is it alloyed with?• Describe gold and how it is used in jewellery.
Gold is shiny, does not corrode or tarnish, and is malleable and ductile — good properties for jewellery. The gold used in jewellery is alloyed with (mixed with) other metals such as silver, copper and zinc to make it harder.
69. Why is silicon called a metalloid or semi-metal?
• What is special about the properties of silicon?• Explain the term “semi-metal” using silicon.
Silicon is called a metalloid (semi-metal) because it has some properties in common with metals and some in common with non-metals.
70. Where are metalloids like silicon found on the periodic table?
• Why does silicon sit between metals and non-metals?• What is the position of semi-metals on the table?
Metalloids (semi-metals) such as silicon lie along the stepped dividing line between the metals and the non-metals, because they share some properties of each.
71. What is stainless steel used for?
• Give a use of stainless steel.• Name a product made from stainless steel.
Stainless steel is used to make washing machines and tumble driers (it resists rusting).
72. Tungsten and nichrome have a property in common — what is it, and what use comes from it?
• What shared property makes tungsten and nichrome useful in heating and lighting?• Suggest a use based on the high resistance of tungsten and nichrome.
Both tungsten and nichrome have high resistance, so they heat up and glow when an electric current passes through them. This makes them useful for light-bulb filaments and for the heating elements in electric heaters, toasters and hair driers.
Board Exercise
Exercise: Multiple Choice
Board-style MCQs with the correct option and full working.
Exercise — Multiple Choice Questions
Tip: For electron-configuration MCQs, just fill the shells: 2, then 8, then the rest. Sulphur (16) → 2,8,6.
73. What is the electron configuration of sulphur? (a) 2,6,8 (b) 2,8,6 (c) 6,8,2 (d) 6,2,8
• Which option shows the correct electron arrangement of sulphur?• Choose the correct electron configuration for sulphur (atomic number 16).
(b) 2,8,6. Sulphur has 16 electrons, filling as 2 in the first shell, 8 in the second and 6 in the outer shell.
74. A period in the periodic table… (a) lists elements left→right in ascending atomic number (b) left→right in descending (c) right→left in ascending (d) right→left in descending
• Which statement correctly describes a period?• Choose the correct description of a period.
(a) A period lists elements from left to right in order of ascending (increasing) atomic number.
75. All the elements in the same group have… (a) a different number of electrons in the outer shell (b) a different number of protons in the outer shell (c) the same number of electrons in the outer shell (d) the same number of protons in the outer shell
• What do elements in the same group share?• Choose the correct statement about elements in a group.
(c) They have the same number of electrons in their outer shell — which is why they behave similarly.
76. Most metals… (a) are naturally shiny (b) can be pulled into wires (c) have low melting and high boiling points (d) make no sound when hit
• Which statement is true of most metals?• Choose the correct property of most metals.
(a) are naturally shiny. Lustre (shininess) is a property of all metals. (Metals are usually ductile and sonorous too, and they have HIGH melting and boiling points — so options (c) and (d) are wrong.)
77. Which is the best property of lead that makes it a good material for roofs? (a) it can be hammered into many shapes (b) it conducts electricity, a safety feature in lightning (c) it conducts heat, keeping the building cool (d) its colour matches the building
• Why is lead a good material for roofing?• Choose the property of lead most useful for roofs.
(a) It can be hammered into many shapes — lead is malleable, so it can be bent and shaped to waterproof a roof.
Board Exercise
Exercise: True or False
Each statement judged true/false with the reason.
Exercise — True or False
78. True or false: The periodic table is a system for arranging all of the chemical elements.
• Is it true that the periodic table arranges all the chemical elements?• State whether true or false: the periodic table arranges all chemical elements.
True. The periodic table is a system for arranging all the chemical elements.
79. True or false: The number of protons and electrons added together is called the atomic number.
• Is the atomic number the sum of protons and electrons?• State whether true or false: atomic number = protons + electrons.
False. The atomic number is the number of protons only (not protons + electrons). Adding protons and neutrons gives the mass number.
80. True or false: Elements at the bottom of all groups are more reactive than those at the top.
• Is it true that in every group the bottom elements are the most reactive?• State whether true or false: reactivity increases down the group in all groups.
False. This is true only for the metal groups (like I and II). In the halogens (Group VII) the elements at the TOP are the most reactive, so reactivity does not increase down every group.
81. True or false: Metals are strong due to their low density.
• Is the strength of metals caused by low density?• State whether true or false: metals are strong because they have low density.
False. Metals are generally strong, but this is not because of low density — in fact many metals have high density. Strength and density are separate properties.
82. True or false: Brass is a sonorous alloy used for making musical instruments.
• Is brass a sonorous alloy used in musical instruments?• State whether true or false: brass is sonorous and used for instruments.
True. Brass is a sonorous alloy (copper + zinc) used for making musical instruments and bells.
Board Exercise
Exercise: Element Data
Reading the Group I data table and its melting/boiling-point trends.
Exercise — Element Data Table (Li, Na, K, Rb)
Note: The four elements are Group I alkali metals. Down the group, melting point and boiling point both FALL.
83. Name the four elements listed (relative atomic masses 6.9, 23.0, 39.1, 85.5).
• Which four elements have these atomic masses: Li 6.9, Na 23.0, ? 39.1, Rb 85.5?• Identify the four elements in the data table.
They are Lithium (6.9), Sodium (23.0), Potassium (39.1) and Rubidium (85.5). The element with atomic mass 39.1 is potassium (K).
84. To which group of the periodic table do these four elements belong?
• Lithium, sodium, potassium and rubidium are all in which group?• Name the group these four metals belong to.
They all belong to Group I — the alkali metals (each has one electron in its outer shell).
85. What information do the melting-point and boiling-point graphs give you about these elements?
• As relative atomic mass increases in Group I, what happens to melting and boiling points?• What trend do the graphs of melting and boiling point against atomic mass show?
The graphs show that as the relative atomic mass increases (going down Group I), both the melting point and the boiling point decrease. So the alkali metals have lower melting and boiling points further down the group.
86. How would you draw a graph of melting point against relative atomic mass for these elements?
• Describe how to plot melting point (and boiling point) against atomic mass.• What goes on each axis when plotting these values?
Put relative atomic mass on the horizontal (x) axis and temperature in °C on the vertical (y) axis. Plot each element’s melting point and join the points, then plot the boiling points on the same axes. Both lines slope downwards as atomic mass increases.
Board Exercise
Exercise: Element Names
Elements named after people, countries, planets and a continent.
Exercise — Elements Named After People, Places & Planets
87. Name three elements named after people.
• Give three elements whose names come from famous people.• Which elements are named after scientists?
Three elements named after people are Einsteinium (after Einstein), Curium (after Marie and Pierre Curie) and Mendelevium (after Mendeleev). (Others include Fermium, Nobelium and Rutherfordium.)
88. Name three elements named after countries or places.
• Give three elements whose names come from countries.• Which elements are named after places?
Three elements named after countries/places are Francium (France), Germanium (Germany) and Polonium (Poland). (Others include Nihonium — Japan, and Americium — the Americas.)
89. Name two elements named after a planet.
• Which elements are named after planets?• Give two elements whose names come from planets.
Two elements named after planets are Uranium (after Uranus) and Neptunium (after Neptune). (Plutonium, after Pluto, is another.)
90. Name one element named after a continent.
• Which element is named after a continent?• Give an element whose name comes from a continent.
Europium is named after the continent of Europe. (Americium, after the Americas, is also acceptable.)
Board Exercise
Exercise: Periodic-Table Diagram
How to read group, period and metal/non-metal from a labelled outline.
Exercise — Reading the Periodic-Table Outline
Note: Read GROUP from the column (far-left = I, far-right = VIII/0) and PERIOD from the row (top row = 1, next = 2 …). Use these rules on your own labelled diagram.
91. In an outline periodic table, which labelled element has the fewest electrons?
• How do you tell which element has the fewest electrons from its position?• Which position on the table has the fewest electrons?
The element with the fewest electrons is the one furthest to the top-left of the table (the lowest atomic number). That top-left position is hydrogen, which has just 1 electron.
92. In the outline periodic table, which labelled element is a noble gas?
• How do you identify the noble gas from its position?• Which column contains the noble gas?
The noble gas is the element in the far right-hand column (Group VIII/0), because that column holds the unreactive gases with full outer shells.
93. To which group does a labelled element belong — how do you work it out?
• How do you read an element’s group from its column?• How is the group number found from the diagram?
Read the group from the vertical column: the far-left column is Group I and the far-right is Group VIII/0. Count across the columns to find the group of each labelled element (an element in the last column is a Group VIII/0 noble gas).
94. In which period does a labelled element lie — how do you decide?
• How do you read an element’s period from the table?• How is the period found from the diagram?
Read the period from the horizontal row: the top row is Period 1, the next is Period 2, and so on down the table. Whichever row a labelled element sits in gives its period (the top-left element is in Period 1).
95. How can you tell from the diagram which elements are metals and which are non-metals?
• Which side of the table has metals and which has non-metals?• How do you classify the labelled elements as metals or non-metals?
Use the stepped dividing line: elements on the left of the line are metals and those on the right are non-metals. Label each element by which side of the line it falls on.
96. Suggest how two Group I elements would react when placed in water, and explain.
• If two labelled elements are alkali metals, how would they react with water?• Explain the likely reaction of Group I elements with water and which is more reactive.
If they are Group I (alkali) metals, they react with water — giving off hydrogen gas and forming an alkaline solution. The one further DOWN the group is more reactive, so it reacts more violently (reactivity increases down Group I).
Board Exercise
Exercise: Explanations & Investigation
Explanation questions plus the tin/lead/solder melting-point practical.
Exercise — Explanations & the Melting-Point Investigation
Tip: An ALLOY (like solder) often melts at a LOWER temperature than the pure metals it is made from. Order of melting: solder → tin → lead.
97. Why is the inside of a steel food can coated with tin, a less reactive metal than iron?
• Explain why tin is used to coat the inside of steel food cans.• What is the purpose of the tin coating on a food can?
Tin is less reactive than iron, so the tin coating forms a protective barrier that stops the iron reacting. This prevents the steel from rusting and stops the iron reacting with the food inside the can.
98. When tin, lead and solder are heated together, in what order do they melt?
• Which metal melts first, second and third: tin, lead or solder?• Rank tin, lead and solder by melting order.
Solder melts first (lowest melting point), tin melts second, and lead melts last (third). Solder is a tin–lead alloy with a lower melting point than either pure metal.
99. What properties do tin, lead and solder have in common?
• What is similar about these three metals?• List properties shared by tin, lead and solder.
They are all metals — shiny, malleable, good conductors of heat and electricity, solid at room temperature, and they all melt when heated strongly.
100. In what way are the three metals different?
• How do tin, lead and solder differ from each other?• What differs between these three metals?
They have different melting points (solder lowest, then tin, then lead), and they differ in appearance/colour and in hardness.
101. What does this experiment tell you about the melting points of metals?
• What general conclusion about metals can you draw from the melting experiment?• What does comparing tin, lead and solder show?
It shows that different metals have different melting points, and that an alloy (solder) can have a lower melting point than the pure metals it is made from.
102. How does the melting point of solder compare with that of tin and lead? Suggest a reason.
• Why does solder melt at a lower temperature than both tin and lead?• Explain why an alloy like solder has a lower melting point.
Solder’s melting point is lower than that of both tin and lead. This is because mixing the two metals (alloying) disturbs the regular arrangement of their atoms, making the solid easier to melt — so it melts at a lower temperature than either pure metal.
103. Why is it important to use flux-free solder in this experiment?
• Suggest a reason for using solder without flux.• What problem would flux cause in the melting-point test?
Flux melts at a low temperature and would melt before the solder, giving a misleading result for the solder’s true melting point (and producing extra fumes). Using flux-free solder keeps the test fair and safe.
104. What safety precautions are needed when melting metals like tin, lead and solder?
• Why must you take care with molten metal and lead fumes?• List the safety notes for the melting-points experiment.
Wear safety goggles at all times, avoid contact with molten metal (it is very hot and will burn), and avoid inhaling the fumes because lead fumes are toxic.
Key Terms
Chapter Vocabulary
The important words in Chapter 5 and what each one means.
| Term | Meaning |
|---|---|
| Periodic table | A system for arranging all the chemical elements in order of increasing atomic number. |
| Atomic number | The number of protons in an atom; it fixes the element’s position in the table. |
| Electron arrangement (configuration) | How an atom’s electrons are shared among its shells, written inside-out, e.g. sodium 2,8,1. |
| Shell (K, L, M) | The energy levels around the nucleus; K holds 2, L holds 8, M holds up to 18 but is stable at 8. |
| Period | A horizontal row of the periodic table; atomic number increases from left to right. |
| Group | A vertical column of the periodic table; its elements have the same number of outer-shell electrons. |
| Alkali metals (Group I) | Very reactive metals with 1 outer electron; reactivity increases down the group. |
| Alkaline earth metals (Group II) | Metals with 2 outer electrons; reactivity increases down the group. |
| Halogens (Group VII) | Reactive, coloured, poisonous non-metals with 7 outer electrons; reactivity decreases down the group. |
| Noble gases (Group VIII/0) | Unreactive gases with completely full outer shells. |
| Reactivity | How readily an element takes part in a chemical reaction. |
| Metal | An element that is shiny, malleable, ductile, sonorous and a good conductor; found left of the dividing line. |
| Non-metal | An element found to the right of the dividing line; generally not shiny, malleable or a conductor. |
| Metalloid (semi-metal) | An element such as silicon with some metal and some non-metal properties; sits on the dividing line. |
| Malleable | Able to be hammered or bent into shape without breaking (e.g. lead). |
| Ductile | Able to be pulled (drawn) into wires (e.g. tungsten, copper). |
| Sonorous | Making a ringing sound when hit (e.g. brass). |
| Lustrous | Having a shiny surface — a property of metals. |
| Alloy | A mixture of a metal with one or more other elements (e.g. steel, brass, solder). |
| Steel | An alloy of iron; strong and able to withstand high temperatures. |
| Brass | A sonorous alloy of copper and zinc used for instruments and bells. |
| Solder | A tin–lead alloy with a lower melting point than either pure metal. |
| Sodium hypochlorite | The chlorine compound found in household bleach. |
| Mass number | The number of protons plus neutrons in an atom (shown in the element’s box). |
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