Atoms, molecules and compounds - C1

Atoms, molecules and compounds - C1

1. Atoms

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

2. Displayed and molecular formulas

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

3. formulas to remember

   • all numbers within formula small and below letters
   • CO2 - Carbon dioxide
   • H2 - Hydrogen
   • H2O - Water
   • O2 - Oxygen
   • CO - Carbon monoxide
   • HCl - Hydrochloric acid
   • CaCl2 - Calcium chloride
   • MgCl2 - Magnesium chloride
   • Na2CO3 - Sodium Carbonate
   • CaCO3 - Calcium Carbonate
   • H2SO4 - Sulfuric Acid
   • MgSO4 - Magnesium sulfate