Explain — 4 marks
A student is learning about the periodic table and how elements are arranged. She notices that sodium (Na) is in Group 1 and has a melting point of 98°C, while chlorine (Cl) is in Group 17 and is a gas at room temperature. She wonders why elements in the same period behave so differently.
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(a) Explain what the group number tells us about sodium (Na) in Group 1.
[1 mark]
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(b) Explain why chlorine (Cl) is a gas at room temperature whilst sodium (Na) is a solid.
[2 marks]
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(c) Explain how the periodic table is arranged and why sodium and chlorine are in different groups despite being in the same period.
[1 mark]
Show mark scheme
- (a) Group 1 elements have one electron in their outer shell / valence shell
- (b) Sodium is a metal with strong metallic bonding between atoms, requiring high energy to break these bonds, so it has a high melting point and is solid at room temperature (1 mark)
- (b) Chlorine is a non-metal with weak intermolecular forces between Cl₂ molecules, requiring low energy to overcome these forces, so it has a low melting point and is a gas at room temperature (1 mark)
- (c) The periodic table is arranged by atomic number / increasing number of protons, and elements are placed in groups based on the number of electrons in their outer shell, so sodium (1 outer electron) and chlorine (7 outer electrons) are in different groups
State — 2 marks
A student is learning about the organisation of the periodic table and examining a periodic table poster in their classroom. They notice that elements are arranged in rows and columns with specific patterns.
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(a) State what the vertical columns in the periodic table are called.
[1 mark]
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(b) State the name of the horizontal rows in the periodic table.
[1 mark]
Show mark scheme
- (a) Groups (accept: columns or vertical columns)
- (b) Periods (accept: horizontal rows or rows)
Suggest — 5 marks
A student is investigating the properties of different elements. She collects samples of sodium, magnesium, aluminium, and silicon. She observes that sodium is soft and can be cut with a knife, while silicon is very hard and brittle. She wants to understand how the periodic table helps explain these differences.
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(a) Suggest why sodium is a soft metal that can be cut with a knife, whilst silicon is hard and brittle.
[2 marks]
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(b) The student predicts that potassium will be even softer than sodium. Suggest why the periodic table supports this prediction.
[2 marks]
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(c) Suggest how the student could use the periodic table to predict the properties of magnesium, without carrying out any experiments.
[1 mark]
Show mark scheme
- (a) Sodium is a metal with a simple metallic structure/bonding (1 mark)
- (a) Silicon is a non-metal with a giant covalent/atomic structure/bonding, which is harder to break (1 mark)
- (b) Potassium is in the same group/column as sodium (1 mark)
- (b) Properties repeat down a group, so potassium should be softer/more reactive than sodium because it is lower in the group (1 mark)
- (c) Look at the position of magnesium in the periodic table and compare its properties to other metals in the same period/group/nearby elements (1 mark)
Calculate — 2 marks
Sodium chloride is produced industrially by the evaporation of seawater or brine. It is used in food seasoning, water treatment, and as a raw material in the chemical industry. Sodium (Na) has atomic number 11 and mass number 23. Chlorine (Cl) has atomic number 17 and mass number 35.
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(a) Calculate the number of neutrons in an atom of sodium.
[1 mark]
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(b) A chloride ion has a charge of 1–. Calculate the number of electrons in a chloride ion.
[1 mark]
Show mark scheme
State — 3 marks
A chemist is selecting halogens for use in industrial chemical synthesis. The chemist needs to consider the reactivity of different halogens when planning the reaction conditions.
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(a) State the trend in reactivity of the halogens going down Group 7.
[1 mark]
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(b) State two reasons why chlorine is more reactive than iodine.
[2 marks]
Show mark scheme
- (a) Reactivity decreases down the group
- (b) Chlorine atoms are smaller (than iodine atoms)
- (b) The outer shell of chlorine is closer to the nucleus
- (b) Chlorine has fewer electron shells
- (b) The force of attraction between nucleus and electrons is stronger in chlorine
GCSE Perfect