periodic table

The periodic table

• 
• The periodic table:
• The number of protons dictates the element
• Non-metals will always gain electrons and have negative ions
• Metals will always lose electrons and have positive ions
• elements usually get more reactive as you go down the groups apart from noble gases
• Alkaline metals have a decreasing melting point the lower down the table you go
• Periods run horizontally
• Groups run vertically

Calculating the mass of subatomic particles

• How to calculate the mass of subatomic particles:
• atomic number is the no. of protons in the atom
• there are the same no. of protons to electrons to make the charge equal 0
• neutron mass = atomic mass - atomic no.
• 1 neutron = 1 unit
• 1 proton = 1 unit