AQA AS CHEMISTRY (7404/1) Question
Paper 1 and Mark Scheme May 2025
C1 Atomic Structure
What are atoms?
Atoms are the particles that make up everything
What is an element?
An element is a substance in which all the atoms are the same
Where are elements shown?
Elements are shown in the Periodic table
How many elements are there?
There are around 118 elements
What is a compound?
A compound is a substance that contain two or more elements chemically combined
Describe the properties of compounds
The properties of compounds are usually different to the elements that they are made
from
What is a mixture?
A mixture is a substance with different elements or compounds not chemically
combined
Give an example of a mixture
An example of a mixture is sand and water as they are not chemically combined and
can be separated by physical means
What is a molecule?
A molecule is a substance that has any elements chemically joined
What does a chemical formula tell you about a molecule?
A chemical formula tells the elements in a molecule and the number of atoms of each
element
How is a chemical formula presented?
Each element symbol starts with a capital letter, if there is a second letter it is in lower
case
Give an example of a chemical formula
,What are state symbols?
State symbols show the physical state of the substance solid (s), liquid (l), gas (g), or
dissolved in water (aq)
Name three properties of Metals
-Strong
-Good conductors of heat and electricity
-High melting and boiling points
Name three properties of Non-Metals
-Weak
-Bad conductors of heat and electricity
-Low melting and boiling points
State the four different ways of separating mixtures
Four different ways of separating mixtures are filtration, crystallisation, distillation or
chromatography
Describe the process of filtration
Pour your mixture onto the filter paper, the liquid simply passes through the filter paper
into the flask. The insoluble solid cannot pass through and so it stays on the paper
Describe the process of crystallisation
Use the method of filtration to filter off any excess soluble solid. Evaporate the mixture
then transfer the hot mixture onto a dish. Crystals are formed when the mixture has
cooled
Describe the process of simple distillation
First we evaporate the mixture by heating it, the dissolved solid then vaporises. These
vapours condense in the condenser, the dissolved solid then flows into the beaker and
liquid stays in the flask
Describe the process of chromatography
Take a strip of filter paper and draw a line on the bottom of the paper. Put a small drop
of ink on the line, take a jar full of water up to the line and put the filter paper in. As the
water moves up we see different colours on the paper these are the dyes in the ink
What were the early ideas of the structure of atoms?
Early ideas of the structure of atoms stated that they are tiny spheres that cannot be
divided
What is the plum pudding model?
, The plum pudding model is what scientists suggested is the structure of atoms is after
the discovery of the electron
Describe the plum pudding model
The plum pudding model suggested that an atom is a ball of positive charge with
negative electrons in embedded in it
Describe how Rutherford carried out the gold foil experiment
Rutherford took a piece of gold foil, he then fired tiny positive alpha particles at the
gold foil
What did Rutherford observe in the experiment?
Rutherford observed that most of the particles when straight through the gold foil and
sometimes the alpha particles bounce back of the gold foil
What did Rutherford discover from these observations?
Rutherford discovered that atoms are mainly empty space as most of the alpha
particles went straight through the gold atoms and that the nucleus of the atom is very
small as only a small number of alpha particles bounce back
Describe the structure of the nuclear model
The nuclear model states that most of an atom is empty space, in the centre is the
nucleus which contains protons and neutrons around the edge we find electrons
What is the Relative mass and the relative charge of protons, neutrons and electrons?
Why do atoms have the same number of protons as electrons?
Because atoms have have no overall charge
What is an Ion?
An ion is a charged particle, it is possible to get positive or negative ions
What is an Isotope?
Atoms of the same element with different numbers of neutrons are called isotopes
What is the mass number of an element?
The mass number is the number on the top of an element it is the number of proton and
neutrons combined
What is the atomic number of an element?
The atomic number is the number on the bottom it is number of protons in an atom,
which is the same as the number of electrons
How many electrons can you fit in the first, second and third shells?
Paper 1 and Mark Scheme May 2025
C1 Atomic Structure
What are atoms?
Atoms are the particles that make up everything
What is an element?
An element is a substance in which all the atoms are the same
Where are elements shown?
Elements are shown in the Periodic table
How many elements are there?
There are around 118 elements
What is a compound?
A compound is a substance that contain two or more elements chemically combined
Describe the properties of compounds
The properties of compounds are usually different to the elements that they are made
from
What is a mixture?
A mixture is a substance with different elements or compounds not chemically
combined
Give an example of a mixture
An example of a mixture is sand and water as they are not chemically combined and
can be separated by physical means
What is a molecule?
A molecule is a substance that has any elements chemically joined
What does a chemical formula tell you about a molecule?
A chemical formula tells the elements in a molecule and the number of atoms of each
element
How is a chemical formula presented?
Each element symbol starts with a capital letter, if there is a second letter it is in lower
case
Give an example of a chemical formula
,What are state symbols?
State symbols show the physical state of the substance solid (s), liquid (l), gas (g), or
dissolved in water (aq)
Name three properties of Metals
-Strong
-Good conductors of heat and electricity
-High melting and boiling points
Name three properties of Non-Metals
-Weak
-Bad conductors of heat and electricity
-Low melting and boiling points
State the four different ways of separating mixtures
Four different ways of separating mixtures are filtration, crystallisation, distillation or
chromatography
Describe the process of filtration
Pour your mixture onto the filter paper, the liquid simply passes through the filter paper
into the flask. The insoluble solid cannot pass through and so it stays on the paper
Describe the process of crystallisation
Use the method of filtration to filter off any excess soluble solid. Evaporate the mixture
then transfer the hot mixture onto a dish. Crystals are formed when the mixture has
cooled
Describe the process of simple distillation
First we evaporate the mixture by heating it, the dissolved solid then vaporises. These
vapours condense in the condenser, the dissolved solid then flows into the beaker and
liquid stays in the flask
Describe the process of chromatography
Take a strip of filter paper and draw a line on the bottom of the paper. Put a small drop
of ink on the line, take a jar full of water up to the line and put the filter paper in. As the
water moves up we see different colours on the paper these are the dyes in the ink
What were the early ideas of the structure of atoms?
Early ideas of the structure of atoms stated that they are tiny spheres that cannot be
divided
What is the plum pudding model?
, The plum pudding model is what scientists suggested is the structure of atoms is after
the discovery of the electron
Describe the plum pudding model
The plum pudding model suggested that an atom is a ball of positive charge with
negative electrons in embedded in it
Describe how Rutherford carried out the gold foil experiment
Rutherford took a piece of gold foil, he then fired tiny positive alpha particles at the
gold foil
What did Rutherford observe in the experiment?
Rutherford observed that most of the particles when straight through the gold foil and
sometimes the alpha particles bounce back of the gold foil
What did Rutherford discover from these observations?
Rutherford discovered that atoms are mainly empty space as most of the alpha
particles went straight through the gold atoms and that the nucleus of the atom is very
small as only a small number of alpha particles bounce back
Describe the structure of the nuclear model
The nuclear model states that most of an atom is empty space, in the centre is the
nucleus which contains protons and neutrons around the edge we find electrons
What is the Relative mass and the relative charge of protons, neutrons and electrons?
Why do atoms have the same number of protons as electrons?
Because atoms have have no overall charge
What is an Ion?
An ion is a charged particle, it is possible to get positive or negative ions
What is an Isotope?
Atoms of the same element with different numbers of neutrons are called isotopes
What is the mass number of an element?
The mass number is the number on the top of an element it is the number of proton and
neutrons combined
What is the atomic number of an element?
The atomic number is the number on the bottom it is number of protons in an atom,
which is the same as the number of electrons
How many electrons can you fit in the first, second and third shells?
