Chemistry

Chemistry Revision Sheet

1. Atomic structure Key Pages: 4 - 21

2. Isotopes

3. Mass spectrometer - How does it work?

(Working out relative atomic mass from isotope)

4. Electronic structure (s, p, d)

5. Patterns in ionisation energies

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Atomic Structure

Relative Mass

Proton (p) Neutron (n) Electron (e-)

Relative Mass 1 1 1/1836

Relative Charge +1 0 -1

Atomic Number = Proton Number

The Mass Number is the sum of protons and the number of neutrons in the nucleus of an atom.

23 Я Mass Number

Na

11 Я Atomic Number

The Neutron number can be found by subtracting the atomic number from the mass number

Isotopes

Isotopes are atoms of the same elements with the same atomic number but a different mass number

Isotopes have the same chemical properties because they have the same number of electrons. The electrons are the particles which are involved in chemical reactions.

Isotopes have different numbers of neutrons and this affects their physical properties. An isotope with fewer neutrons have:

Lower masses

Lower densities

Faster rates of diffusion

Lower melting and boiling points

Mass Spectrometer

Used to measure the relative masses of isotopes

Used to find the relative abundance of the isotopes in a sample of an element

When charged particles pass through a magnetic field, the particles are deflected by the magnetic field, and the amount of deflection depends upon the mass/charge ratio of the charged particle

VAPORISATION

The sample has to be in