OCR Gateway GCSE Chemistry

Topic Questions

GCSEChemistryOCR GatewayTopic Questions4. Predicting & Identifying Reactions & Products4.1 Predicting Chemical Reactions

4.1 Predicting Chemical Reactions

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Hard
1a2 marks

Sodium is in Group 1 of the Periodic Table.

Sodium reacts with water to make sodium hydroxide, NaOH, and hydrogen.

Write the balanced symbol equation for the reaction between sodium and water.

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1b1 mark

Higher Only 

Sodium ions, Na+, are formed when sodium reacts with water.

Look at the equation. It shows how a sodium ion is formed from a sodium atom.

Na – e− → Na+
The symbol e− means an electron.

The formation of a sodium ion from a sodium atom is an example of oxidation.

Explain why.

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1c2 marks

Rubidium is another element in Group 1.

Rubidium reacts much faster than sodium does.

Explain why.

Use ideas about electrons in your answer.

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1a1 mark

The Group 7 elements are called the halogens.

The table shows information about some of the halogens.

Name Atomic number Boiling point
(°C)		 State at room
temperature		 Molecular
formula
Fluorine 9 −188 Gas F2
Chlorine 17 −34 Gas Cl2
Bromine 35 59 Liquid Br2
Iodine 53 184 Solid I2

Which is the most reactive halogen in the table?

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1b2 marks

Astatine is also a halogen. It has the atomic symbol At and an atomic number of 85.

Look at the table.

i)
Predict the state of astatine at room temperature.

[1]

ii)
Predict the boiling point of astatine.

[1]

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1c3 marks

Sodium, Na, reacts with chlorine. A white solid is made.

i)
What is the name of this white solid?

[1]

ii)
Write down the balanced symbol equation for this reaction.

[2]

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2a2 marks

This question is about elements in the Periodic Table.

Look at the table. It shows some properties of Group 7 elements.

Element Molecular formula State at room temperature Radius of an atom (nm) Order of
reactivity
Fluorine F2 ......................... 0.072

most reactive

least reactive
Chlorine Cl2 gas 0.099
Bromine Br2 liquid 0.114
Iodine I2 solid 0.133
Astatine At2 solid ........................

Complete the table. Use ideas about trends down a Group to help you.

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2b4 marks

In the table, the Group 7 elements are listed in order of reactivity.

The equations show a displacement reaction of Group 7 elements.


chlorine + sodium bromide → sodium chloride + bromine
Cl2        +         2NaBr           →              2NaCl     +     Br2

i)
Complete the word equation.

bromine + sodium iodide → ................... + ...................
[1]

ii)
There is no reaction between iodine and sodium bromide.

Explain why.
[1]
iii)
Chlorine reacts with sodium iodide. Sodium chloride and iodine are made.

Write the balanced symbol equation for this reaction.
[2]

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2c1 mark

Group 1 is another group of elements in the Periodic Table.

i)

Potassium is a Group 1 metal.

Potassium is stored under oil because it is very reactive.

q16ci-paper-2-nov-2020-ocr-gcse-chem

What does the oil stop the potassium reacting with?

[1]

ii)
Sodium is another Group 1 metal.

Sodium reacts in a similar way to potassium.

Explain why.

Use ideas about atomic structure in your answer.
[1]

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3a2 marks

This question is about the properties of elements in Groups 1, 7 and 0.

Lithium, sodium and potassium are all Group 1 elements.

A teacher adds a small piece of potassium to a trough of water, as shown in the diagram.

q20a-paper-4-june-2019-ocr-gcse-chem

The potassium fizzes and a gas is produced.

Describe what else you would observe.

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3b2 marks

Reactivity increases going down Group 1 from lithium to potassium.

Explain this trend in reactivity.

Use ideas about the electronic configurations of the atoms in your answer.

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3c3 marks

Look at the table. It shows information about the Group 7 elements.

Complete the table.

Element Formula Colour State at room temperature
Fluorine F2 pale yellow gas
Chlorine Cl2 ......................... .........................
Bromine Br2 brown liquid
Iodine I2 grey .........................

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3d2 marks

The Group 7 elements exist as simple molecules.

Fluorine boils at −188°C.

Explain why fluorine has a low boiling point.

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3e2 marks

The elements in Group 0 (the noble gases) are unreactive.

Explain why, in terms of their electronic configurations.

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