chemistry: periodicity

metalic = increases along the group = increaseing electrons in the outer shell = more delocalised electrons = more van de waals forces = increasing boiling point

giant covalent = verry large covalent bonds to break = very high melting point nce the bonds have broken there are week van de waals forces = low boiling point compered to metals

small molecular = week van de waals forces = low melting and boiling points

the atomic radius decreases along the period

this is because the amount of electrons in the outer shell increases so the amount of electro static bonds increses so the outer shell is held more closely to the nucleus

the amount of electrons in the outer shell increases this is where the group number comes from

lithium = 1

berrillium = 2

boron = 3

carbon = 4

nitrogen = 5

oxogen = 6

flourine = 7

neon = 8

element   group number   period number  melting point  boiling point  atomic raddii      structure

lithium         1                          2                       453K             1615K       167pm      metallic

berrylium     2                         2                       1560K           2743K        112pm     metallic

boron          3                         2                       2348K           4273K       87pm       giant cov

carbon       4                         2                         3823K          4300K      67pm       giant cov

nitrogen     5                        2                           63k              77k       56pm        molecular

oxygen     6                         2                           54.8k           90.2k      48pm        molecular

flourine    7                          2                           53.5K           85.3k            42pm      molecular

sodium    1                         3                           370k            1156K          190pm      metallic

genrally first ionisation energy increses across the period exept this is un even

this is because ther are increasing amounts of electrons in the outer shell so the atomic radius decreases so the electrostatic atractions between the electrons and neucleas are stronger so the ionisation energy increases (normally)

ionisation energy decreases down the group due to electron shielding