Atoms, molecules and compounds - C1

1. positive nucleus
2. orbiting electrons
   1. negatively charged
   2. move around nucleus in shells
3. form bonds to make molecules or compounds
   1. electrons
4. can lose or gain 1+ electrons
   1. gives charge
      1. negative (gains)
      2. positive (loses)
   2. charged atoms known as ions
      1. covalent bond
         1. atoms share pair of electrons
         2. ionic bond
            1. positive ion meets negative ion - attracted and join together

1. shows how many atoms in each formula
2. molecular formula
   1. eg. CH4 (Methane)
      1. 1 carbon - 4 hydrogen
3. displayed formula
   1. diagram of CH4 shows atoms and covalent molecules as an image/diagram

Nota:

• all numbers within formula small and below letters

1. CO2 - Carbon dioxide
2. H2 - Hydrogen
3. H2O - Water
4. O2 - Oxygen
5. CO - Carbon monoxide
6. HCl - Hydrochloric acid
7. CaCl2 - Calcium chloride
8. MgCl2 - Magnesium chloride
9. Na2CO3 - Sodium Carbonate
10. CaCO3 - Calcium Carbonate
11. H2SO4 - Sulfuric Acid
12. MgSO4 - Magnesium sulfate