1. BONDING

2. WHY ATOMS COMBINE -1 • All atoms want a full outer shell • Some atoms will lose electrons to empty their shells • These become positively charged ions • Metal atoms will lose electrons • Positive ions are called CATIONS

3. Why atoms combine - 2 • All atoms want a full outer shell • Some atoms will gain electrons to fill their shells • These become negatively charged ions • Non-metal atoms gain electrons • Negative ions are called ANIONS

4. IONS • Ions have full outer shells • Ions have charges • Metals make positive ions • Positive ions have lost electrons • Non-metals form negative ions • Negative ions have extra electrons

5. IONIC BONDING • When electrons are transferred from one atom to another an ionic bond will form • An ionic bond is the attraction between oppositely charged ions • Ions are held by strong ELECTROSTATIC FORCES

6. IONIC COMPOUNDS • Ionic compounds have very high melting points • Ionic compounds dissolve in water (soluble) • Ionic compounds cannot conduct electricity when solid because the ions cannot move, they will conduct when molten (melted) or when dissolved in water (aqueous) • Ionic salts are made of a metal and a non-metal, eg sodium chloride, magnesium oxide

7. Covalent Bonding • All atoms want a full outer shell • Some atoms will share electrons to fill their outer shells • Sharing electrons makes a covalent bond • A molecule is formed when atoms overlap to share electrons • Hydrogen gas, H2, oxygen gas, O2 and water are made up molecules