Download AQA Core Science Final Test - Atoms and Chemical equations

SOLUTIONS
Final test: AQA CORE Science – Atoms and Chemical equations (15 marks)
1. Which one best describes a molecule? (circle the correct answer)
A.
B.
C.
D.
Molecules are two or more atoms bonded together.
Molecues are different atoms bonded together.
Only compounds are molecules
Mixtures don’t contain molecules.
(1 mark)
2. Fill in the gaps using some of the words in the box.
When elements react, their atoms join with other atoms to form compounds. There are two types of
bonds formed in a chemical reaction
atom
molecule
elements
product
two
one
compound
(2 mark)
3. Describe the difference between ionic and covalent bonding.
Ionic Bonding:
 Metal and non-metal react.
 Metals form positive ions, Non-metals form negative ions.
 Metals LOSE electrons Non Metals GAIN electrons.
Covalent Bonding:
 When two non-metals bond.
 Outermost electrons are shared. A pair of shared electrons forms a bond
(3 marks)
4. Describe the structure of the atom.


A central nucleus that contains protons and neutrons.
Surrounded by shells that contain the electrons.
(2 marks)
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5. QWC: Explain how chemical changes can be shown using equations and state simply what the following equation
tells us.
calcium carbonate
CaCO
3

calcium oxide + carbon dioxide

CaO
+
CO
2
QWC Suggested marking guidance (Total 6 marks)
Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard
of the scientific response. Teachers should and apply a ‘best-fit’ approach to the marking.
0 marks
No relevant
content.
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Level 1 (1-2 marks)
Level 2 (3-4 marks)
A simple description of what
A clear description of what the
the equations can tell you.
equations can tell you.
The spelling, punctuation and
There is reasonable accuracy in
grammar are very weak.
spelling, punctuation and grammar,
although there may still be some
errors
Level 3 (5-6 marks)
A detailed explanation of what the
equations show and linked to
conservation of mass.
The answer shows almost faultless
spelling, punctuation and
grammar.
Chemical changes can be shown by using a word or symbol equation.
A word equation only tells you the name of the reactants and products.
A symbol equation tells you the numbers of atoms involved.
The equation shows the same number of atoms go into the reaction as come out.
This is known as conservation of mass.
There is one Calcium atom, one carbon atom and three oxygen atoms in this reaction.
(6 marks)
1
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