AQA AS Chemistry Unit 1

Proton:       Relative mass: 1              Relative charge: +1

Neutron:     Relative mass: 1              Relative charge: 0

Electron:    Relative mass: 1/1840     Relative charge: -1

Atomic Number: number of protons in the nucleus of the atom.

Mass Number: total number of protons and neutrons in nucleus of an atom.

Number of Neutrons: mass number - atomic number.

Number of Electrons: number of protons.

Isotopes: atoms of the same element with different mass numbers. Properties: same chemical properties, different physical properties, different rates of diffusion, radioactivity. Different numbers of neutrons but the same number of protons.

- Known as Orbitals

- A orbital can hold upto two electrons

- Each sub-shell has different orbitals s, p, d,f

- Electrons have a property called "spin"

- Each electron is often shown with an arrow