GCSE CHEMISTRY AQA SCIENCE EXAM REVISION QUESTIONS
WITH VERIFIED SOLUTIONS LATEST 2025 UPDATE.
Draw and label an atom - ANSWER- Protons
Neutrons
Electrons
What are the masses and charges of these parts of an atom?
• Proton
• Neutron
• Electron - ANSWER- Protons = +ve
(mass 1)
Neutrons = neutral
(mass 1)
Electrons = -ve
(mass 1/2000th)
Why do atoms usually have no overall electrical charge? - ANSWER- Atoms usually have no
overall charge because they have equal numbers of protons (+ve) and electrons (-ve), which cancel
one another out
All atoms of a particular element (e.g. carbon) all have the same number of what? - ANSWER-
Protons
,What does relative atomic mass tell you about the atom? - ANSWER- The number of protons
and neutrons in the atom
What does atomic number tell you about the atom? - ANSWER- The number of protons
(usually the same as the number of electrons)
What is an isotope? - ANSWER- An isotope is an atom with a different amount of neutrons
How many electrons can occupy the 1st and 2nd shell (energy level) of an atom? - ANSWER-
2 in the 1st shell and 8 in the 2nd shell
The electron structure of sodium can be represented as 2,8,1 - what does this mean?
Represent these atoms: -
• Fluorine
• Oxygen
• Potassium
• Magnesium - ANSWER- 2,8,1 means 2 electrons in the 1st shell, 8 electrons in the 2nd shell
and 1 electron in the 3rd shell
Fluorine = 2,7
Oxygen = 2,6
Potassium = 2,8,8,1
Magnesium = 2,8,2
Define these terms: -
, • Element
• Compound
• Mixture - ANSWER- Element - a pure substance made from 1 type of atom only
Compound - 2 or more elements chemically bound
Mixture - 2 or more elements or compounds mixed together which are not chemically bound
What happens to the electrons of 2 atoms when they chemically react? - ANSWER- During a
chemical reaction electrons are either given away, taken, or shared
What is an ion?
How are +ve ions formed?
How are -ve ions formed? - ANSWER- An ion is an atom with a charge
+ve ions have lost electrons
-ve ions have gained electrons
Explain how the following atoms become ions (will they be +ve or -ve)?
• Potassium
• Magnesium
• Chlorine
• Oxygen - ANSWER- Potassium - loses 1 electron (K+)
WITH VERIFIED SOLUTIONS LATEST 2025 UPDATE.
Draw and label an atom - ANSWER- Protons
Neutrons
Electrons
What are the masses and charges of these parts of an atom?
• Proton
• Neutron
• Electron - ANSWER- Protons = +ve
(mass 1)
Neutrons = neutral
(mass 1)
Electrons = -ve
(mass 1/2000th)
Why do atoms usually have no overall electrical charge? - ANSWER- Atoms usually have no
overall charge because they have equal numbers of protons (+ve) and electrons (-ve), which cancel
one another out
All atoms of a particular element (e.g. carbon) all have the same number of what? - ANSWER-
Protons
,What does relative atomic mass tell you about the atom? - ANSWER- The number of protons
and neutrons in the atom
What does atomic number tell you about the atom? - ANSWER- The number of protons
(usually the same as the number of electrons)
What is an isotope? - ANSWER- An isotope is an atom with a different amount of neutrons
How many electrons can occupy the 1st and 2nd shell (energy level) of an atom? - ANSWER-
2 in the 1st shell and 8 in the 2nd shell
The electron structure of sodium can be represented as 2,8,1 - what does this mean?
Represent these atoms: -
• Fluorine
• Oxygen
• Potassium
• Magnesium - ANSWER- 2,8,1 means 2 electrons in the 1st shell, 8 electrons in the 2nd shell
and 1 electron in the 3rd shell
Fluorine = 2,7
Oxygen = 2,6
Potassium = 2,8,8,1
Magnesium = 2,8,2
Define these terms: -
, • Element
• Compound
• Mixture - ANSWER- Element - a pure substance made from 1 type of atom only
Compound - 2 or more elements chemically bound
Mixture - 2 or more elements or compounds mixed together which are not chemically bound
What happens to the electrons of 2 atoms when they chemically react? - ANSWER- During a
chemical reaction electrons are either given away, taken, or shared
What is an ion?
How are +ve ions formed?
How are -ve ions formed? - ANSWER- An ion is an atom with a charge
+ve ions have lost electrons
-ve ions have gained electrons
Explain how the following atoms become ions (will they be +ve or -ve)?
• Potassium
• Magnesium
• Chlorine
• Oxygen - ANSWER- Potassium - loses 1 electron (K+)
