AQA GCSE Chemistry Paper 1

What is an atom?

Smallest part of an element that can exist

What is an element?

A substance made up of one type of atom

How are elements represented?

Using symbols, in the periodic table

Approximately how many elements are there?

100

What is a compound?

A substance made up of two or more elements chemically combined in fixed proportions

How are the elements in a compound separated?

By chemical reaction

How are chemical reactions represented?

By word or symbol equations

Which group of the periodic table includes sodium and potassium?

Group 1, alkali metals

Which group of the periodic table includes chlorine, bromine and iodine?

Group 7, halogens

Which group of the periodic table includes helium, neon and argon?

Group 0, noble gases

What information does a chemical formula provide?

Which elements are bonded together, and how many atoms of each are present

What is a mixture?

Two or more elements or compounds not chemically bonded together

Which separation technique is used to separate a mixture of two liquids?

Distillation

Which separation technique is used to separate a mixture of more than two liquids?

Fractional distillation

Which separation technique is used to separate an insoluble solid and a liquid?

Filtration

Which separation technique is used to separate a mixture of coloured substances?

Chromatography

Which separation technique is used to separate a soluble solid from its solution?

Crystallisation

Before the discovery of the electron what were atoms thought to be?

Tiny spheres that could not be divided

What is the 'plum pudding' model of the atom?

Ball of positive charge with negative electrons embedded in it

What experiment led to the development of the nuclear model?

Rutherford's alpha particle scattering experiment

What happened to the alpha particles fired at thin gold foil in Rutherford's scattering experiment?

Most alpha particles went straight through, but a few were scattered

What is the 'nuclear' model of the atom that Rutherford developed that replaced the 'plum pudding' model?

Mass of the atom is in the centre (nucleus) and the nucleus was positively charged

Who proposed that electrons orbit the nucleus at specific distances?

Niels Bohr

What name was given to the positive particles in the nucleus?

Protons

What did James Chadwick discover?

Neutrons

In what order were the subatomic particles discovered?

Electron, proton, neutron

What is the relative charge on a proton?

+1 (positive 1)

What is the relative charge on a neutron?

0 (no charge)

What is the relative charge on an electron?

-1 (negative 1)

Why are atoms electrically neutral?

Number of protons = number of electrons

What name is given to the number of protons in an atom of an element?

Atomic number

What does the atomic number (number of protons) determine?

The element. Atoms of a particular element have the same number of protons

What is the approximate size of an atom?

0.1 nm (1 x 10-10 m)

What is the approximate radius of a nucleus?

1 x 10-14 m

Where is almost all the mass of an atom?

In the nucleus

What is the relative mass of a proton?

1

What is the relative mass of a neutron?

1

What is the relative mass of an electron?

Very small / negligible

What name is given to the sum of the number of protons and neutrons?

Mass number

What are isotopes?

Atoms of the same element with different numbers of neutrons (same number of protons)

What is relative atomic mass, Mr, of an element?

Average mass of an element's atoms, compared to 1/12th the mass of a carbon-12 atom

How is Mr calculated?

Mr = (Ar 1 x abundance 1)/100 + (Ar 2 x abundance 2)/100

What is the 'electronic structure' of an atom?

Shows where in the atoms the electrons are situated

How is the electronic structure of an atom represented?

By numbers or a diagram

Where is the lowest energy level in an atom?

Nearest the nucleus

How many electrons are needed to fill the lowest energy level in an atom?

2

How many electrons are needed to fill the second lowest energy level in an atom?

8

How many electrons are needed to fill the third lowest energy level in an atom?

8

How are the elements arranged in the periodic table?

In order of increasing atomic number

What are the columns in the periodic table called?

Groups

What are the rows in the periodic table called?

Periods

What do all elements in the same group have in common?

They have the same number of electrons in their outer shells, and similar chemical properties

Why is the periodic table called the periodic table?

Similar properties occur at regular intervals

Before the structure of the atom was known, how were elements arranged in the PT?

In order of increasing atomic weight

What problems were there with the early periodic table?

It was incomplete, and some elements were in the wrong group

How did Mendeleev improve the periodic table?

He left gaps for elements he thought hadn't been discovered yet

What made it possible to explain why the elements were not always in the right order?

Knowledge of isotopes

What are metal elements?

Elements that react to form positive ions

What are non-metals?

Elements that do NOT react to form positive ions

Where are metals found in the PT?

Towards the left and the bottom of the table

Where are non-metals found in the PT?

Towards the right and the top of the table

Why do metals lose electrons to become positive ions?

They have small numbers of electrons in their outer shells

Why do non-metals NOT lose electrons to become positive ions?

They have larger numbers of electrons in their outer shells, so easier to gain than lose

What determines how an element will react?

The no. of protons à no. of electrons à where the electrons are à no. in outer shell

What are the elements in Group 0 called?

Noble gases

Why are they unreactive?

They have a full outer shell of electrons

How does the boiling point of the noble gases change with increasing rel. atomic mass?

Boiling point increases down the group

What are elements in Group 1 called?

Alkali metals

How many electrons do the alkali metal atoms have in their outer shells?

1

How does the reactivity change as you go down the group?

It increases as atoms get bigger (outer electrons further from nucleus)

How do alkali metals (M) react with oxygen?

4 M + O2 → 2 M2O

How do alkali metals (M) react with chlorine?

2 M + Cl2 → 2 MCl

How do alkali metals (M) react with water?

2 M + 2 H2O → 2 MOH + H2

What are elements in Group 7 called?

Halogens

How many electrons do halogen atoms have in their outer shells?

7

What type of elements are the halogens?

Non-metals

How do halogen elements (X) exist?

Molecules formed from two atoms (diatomic molecules), X2

How do halogens react with metals?

Halogens react with metals to form ionic compounds called halides

How do halogens react with non-metals?

Halogens react with non-metals to form covalent compounds

How does relative molecular mass, Mr, change as you go down Group 7?

Mr increases down Group 7

How do melting and boiling point change as you go down Group 7?

Melting and boiling point increase down Group 7

How does the reactivity of the halogens change as you go down Group 7?

Reactivity of halogens decreases as you go down Group 7

How do displacement reactions occur in the halogens?

A more reactive halogen will displace a less reactive halogen from its compounds

Where do you find the transition metals in the periodic table?

Between groups 2 and 3

What physical properties to Transition metals have in common with all metals?

Conduct electricity as solids or liquids; are shiny when freshly cut

What physical properties of Transition metals are different to those of group 1?

Transition metals have high melting points, have higher densities, are stronger, are harder

What chemical properties of Transition metals are different to those of group 1?

Transition metals are less reactive, have ions with differrent charges, form coloured compounds

What are the three types of bonding between atoms?

Ionic, covalent and metallic

What is an ionic bond?

An attraction between oppositely charged ions

What is a covalent bond?

A bond formed when two electrons are shared between two atoms

What is a metallic bond?

A bond formed when metal atoms share delocalised electrons

When does ionic bonding occur?

When a metal reacts with a non-metal

When does covalent bonding occur?

When a non-metal reacts with a non-metal

When does metallic bonding occur?

In metals and alloys

Why do atoms of elements react?

In order to get a full outer shell of electrons

Why do Group 0 (noble gas) elements NOT react?

They already have a full outer shell

How does an ionic bond form?

The metal atoms transfers electrons to the non-metal atom

When Group 1 metals react, what charge do their ions have?

1+

When Group 2 metals react, what charge do their ions have?

2+

When Group 3 metals react, what charge do their ions have?

3+