C3 - Atoms, Molecules & Compounds

C3 - Atoms, Molecules & Compounds

1. Atoms

   • Really tiny, positively charged nucleus and negatively charged electrons
     • Electrons move around the nucleus in layers known as shells
   • Can form bonds to make molecules or compounds
     • It's the electrons involved in making bonds
       • If an atom loses one or more electrons it becomes positively charged
       • If an atom gains one or more electrons it becomes negatively charged
   • Charged atoms are known as ions
     • If a positive ion meets a negative ion, they are attracted to another and join
       • This is called an ionic bond
   • The other main bond is called a covalent bond
     • When non-metal atoms join, they form covalent bonds by sharing pairs of electrons
       • Because the bond is a shared pair, no atom loses electrons

2. Molecular Formulas

   • CH4 means Methane
     • It contains 1 Carbon and 4 Hydrogen Atoms
   • CO2
     • Carbon Dioxide
   • H2
     • Hydrogen
   • H2O
     • Water
   • HCl
     • Hydrochloric acid
   • CaCl2
     • Calcium Chloride
   • CO
     • Carbon Monoxide
   • MgCl2
     • Magnesium Chloride
   • CaCO3
     • Calcium Chloride
   • H2SO4
     • Sulfuric acid
   • MgSO4
     • Magnesium Sulfate