F331 - EL

HideShow resource information
  • Created by: Jo D
  • Created on: 18-05-13 16:26

Amount of 'stuff'

Avogadro constant - number of particles in 1 mole of a substance

Relative atomic mass - how much heavier an atom of an element is than 1/12 of a carbon-12 atom

Relative formula mass - sum of relative atomic masses in a molecule

Empirical formula - The simplest ratio of atoms in a compund

Molecular formula - the actual number of atoms of each element in a compound

for example: ethane has the molecular formula C2H6 but the empirical formula CH3

Working out the amount of moles in a substance: mass/Ar OR mass/Mr

1 of 11

A model of the atom


mass number = number of protons + neutrons

atomic number = number of protons


2 of 11


What? atoms of the same element - same atomic number but different mass number

working out the relative atomic mass: need to know relative istopic mass and relative abundance

average relative atomic mass =

(relative isotopic mass x relative abundance) + (relative isotopic mass x relative abundance)/100

3 of 11

Nuclear reactions

radioactive isotopes have unstable nuclei

alpha radiation - helium nuclei, charge +2, nucleus changes with 2 fewer neutrons and protons, stopped by paper or skin, low deflection in electric field

beta radiation - an electron, charge -1, nucleus changes with 1 fewer neutrons and 1 more proton, stopped by aluminium foil, high deflection in electric field

gamma radiation - electromagnetic radiation, charge 0, no change in nucleus, stopped by lead sheet, no deflection in electric field

Half-life: time taken for half the radioactive nuclei to decay

Tracers: the decay is monitored - used in medicine and decay is measured using Geiger Counter. Needs to be long enough to be traced but not long enough to cause harm to body tissues

Nuclear fusion: joining of two or more nuclei - forms heavier nucleus

4 of 11

Light and electrons

energy levels - at ground state, electrons are closest to nucleus. Gap between levels decreases further away from nucleus

Atomic absorption spectrum: black lines on a coloured background. Appear when electrons absord energy (a photon) and jump up to a higher energy level, producing the lines

Atomic emission spectrum: coloured lines on a black background. Appear when electrons absorb a photon and jump up an energy level, when they fall back down a frequency of light is emitted, producing the lines

Electron shells: 1st shell can hold 2 electrons, 2nd shell can hold 8 electrons, 3rd shell can hold 18 electrons, 4th shell can hold 32 electrons

Electron configuration shows how many electrons in each shell

eg. K = Ca = Cu = Fe =

5 of 11

Bonding and properties

Metal + Non-metal = Ionic Transfers electrons to create full outer shells

Non-metal + Non-metal = Covalent Shares pair of electrons to create full outer shells

Metal + Metal = Metallic Pool of delocalised electrons and positive metal ions

Ionic lattice: high melting point, soluble, conducts if molten or in solution

Giant covalent network: high melting point, insoluble, does not conduct

Simple molecular covalent: low melting point, insoluble, does not conduct

Metallic lattice: high melting point, insoluble, conducts

6 of 11

Molecule shapes

Four groups of electron density: bond angle 109     4 bonding pairs = tetrahedral 3 bonding pairs, 1 lone pair = pyramidal 2 bonding pairs, 2     lone pairs = bent

Three groups of electron density : bond angle 120        3 bonding pairs = planar triangular 2 bonding pairs, 1 double bond = planar triangular

Two groups of electron density: bond angle 180     2 bonding pairs = linear 1 triple bond, 1 bonding pair = linear 2 double bonds = linear

7 of 11


  • Mendeleev arranged elements according to relative atomic mass
  • fitted due to chemical and physical properties
  • left gaps for new elements to be discovered
  • predicted properties of those elements

Periodicity - a regular pattern repeated across a period and in other periods       eg. melting points and boiling points

8 of 11

Balanced equations

There should be the same number of each element on both the reactant and product sides of the equation 

eg. Ca + H2O --> Ca(OH)2 + H2 is balanced to Ca + 2H2O --> Ca(OH)2 + H2

9 of 11

Reactions of elements in group 2

Metal + Water --> Metal Hydroxide + Hydrogen

The Oxides

  • metal oxide + water --> metal hydroxide
  • metal oxide + acid --> salt + water

The hydroxides

  • metal hydroxide + acid --> salt + water

The carbonates

  • metal carbonate --> metal oxide + carbon dioxide
10 of 11

Mass Spectrometery

  • sample inlet: gas or liquid injected
  • ionisation area: bombarded with electrons
  • acceleration area: electric field used to give all ions same kinetic energy
  • drift region: a vacuum - heavier molecules travel slower than lighter molecules
  • ion detector: detects positive ions and converts into mass spectrum

The mass spectrum

greatest mass = molecular ion

most intense peak = base peak

11 of 11


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Bonding & shapes resources »