Fundamental Ideas 1.1 Atoms, Elements and Compounds

Fundamental Ideas 1.1 Atoms, Elements and Compounds

1. Atoms, elements and compounds

   • Compound - 2 or more different atoms joined by a chemical bond
   • mixture - 2 different elements. Not joined by a chemical bond.

2. Proton has a + charge, relative mass - 1

   • Neutron is neutral, relative mass - 1
     • Electron has a negative charge and no relative mass
     • relative atomic mass - no of protons.
       • Eg. He(Helium) 4-2 = 2 neutrons
   • Na (sodium) has 11 protons
     • P (phosphorus) has 15 protons
   • No of electrons = no of protons