A Level Aqa Chemistry - (1) Atomic Structure

Front 1

Isotopes Definition

Back 1

Atoms with the same number of protons, but different number of neutrons.

Front 2

Isotopes- Chemical properties

Back 2

They have similar chemical properties (how it reacts) as, they have the same electronic structure.

Front 3

Isotopes- Physical Properties

Back 3

They may have a slight varying physical property due to the difference in masses.

Front 4

Mass (kg) of Protons

Back 4

Front 5

Charge (C) of Protons

Back 5

Front 6

Position of Protons

Back 6

In the nucleus

Front 7

Mass (kg) of Neutrons

Back 7

Front 8

Charge (C) of Neutrons

Back 8

0

Front 9

Position of neutrons

Back 9

In the nucleus

Front 10

Mass (kg) of Electrons

Back 10

(very nearly 0)

Front 11

Charge (C) of Electrons

Back 11

Front 12

Position of Electrons

Back 12

Around the nucleus in orbitals

Front 13

Relative Mass of Protons

Back 13

1

Front 14

Relative Charge of Protons

Back 14

+1

Front 15

Relative Mass of Neutrons

Back 15

1

Front 16

Relative Charge of Neutrons

Back 16

0

Front 17

Relative Mass of Electrons

Back 17

Front 18

Relative Charge of Electrons

Back 18

-1

Front 19

Strong nuclear force

Back 19

A force that holds together the protons and neutrons in the centre of the atom.

It only acts over very short distances within the nucleus.

Front 20

Why is the 'strong nuclear force' much stronger than the 'electrostatic forces'?

Back 20

This is because nuclear force can bind many positively charged protons in a very short space that is in the nuclei of an atom despite the repulsions between them whereas the electrostatic forces holds the protons and electrons together in an atom.

Front 21

What are nucleons?

Back 21

Protons and neutrons. They are called this as, they are found in the nucleus.

Front 22

Atomic number (Z) Definition

Back 22

The number of protons in the nucleus. (The proton number)

Front 23

Why are atoms electrically neutral?

Back 23

The number of electrons in the atom is equal to the proton number, therefore, the charges balances out.

Front 24

Atomic numbers of elements

Back 24

Atoms of the same element have the same atomic number. Atoms of different elements have different atomic numbers.

Front 25

Mass Number (A) Definition

Back 25

The mass number is the total number of protons and neutrons in the nucleus.

Front 26

Mass of an atom

Back 26

The nucleons are responsible for almost all of the mass of an atom as, the electrons weigh virtually nothing (negligible).

Front 27

What happens when the isotopes are unstable?

Back 27

The nucleus of the atom breaks down giving off bits of the nucleus or energetic rays.

Front 28

Half-life Definition

Back 28

This is the time taken for half of its radioactivity to decay.

Each radioactive isotope decays at a rate measured by this.

For example, a well-known radioactive isotope is carbon-14.

Front 29

How is carbon-14 produced in the atmosphere?

Back 29

By a nuclear reaction in which a neutron (from a cosmic ray) hits a nitrogen atom and ejects a proton.

Front 30

Atomic model theories used to explain:

Back 30

Dalton's Model- Still used to explain the geometries of crystals.

Bohr's Model- Used for a simple model of ionic and covalent bonding.

The Charged Cloud Idea (J.J Thomson)- Explanation of bonding and the shapes of molecules.

Simple model of electrons orbiting in shells- Used to work out bonding between atoms.

Front 31

The Mass Spectrometer Definition

Back 31

The mass spectrometer can be used to determine all the isotopes present in a sample of an element and to therefore identify elements.

Used to determine the relative atomic masses accurately.