Trend in period 3 / periodicity

i hope it helps i have other chemistry stuff up too so have a look :)

HideShow resource information

First things first

please make sure that you know what affects the first ionisation energy of an atom

shielding (decreases) , distance ( decrease) and proton number (increases)

and the size of and atom or ion

proton number, shielding, and distance

make sure that you know how the periodic table is divided in to S,P ,D blocks - this tells you where the outer elctrons lie in the atom  and where these blocks are located on the periodic table

1 of 4

Atomic radii

across a period they will decrease because the proton number is getting higher , this pulls electrons in very storngly, but the shielding is staying the same making the atom smaller

down  a group they will be bigger as you increase the number of electrons so much that you need another shell of electrons shielding increases and distance has too

distance is the over riding factor of what elffects the size of atoms

2 of 4

first ionisation energy

 the greater the distance/ or shielding the lower the first ionisation energy is , the greater the proton number there is an increase in the first ionisation energy

First ionisation energy will effect the type of bonding which an element will be able to take part in , the only types of bonding present in the Periodic table itself are covalent and metallic for  diatoms etc 

make sure that you know definitions of the different types of bonding that can happen

the general trend in ionisation energies in group 2 and 3 is an increase , i also shows periodicity as does melting point

3 of 4

melting point

the pattern is low high low and this again goes for both groups

these trends come about becuase of the types of bonding in the 2 periods changing from metallic to covalent 

it increases to start because of the metal bonding getting stronger because of the ions being formed getting smaller and the charges getting greater as well as a lower distance between the electrons and nucleus

however when the bonding type is no longer metallic you get covalently  bonded elements which have weak forces  of attraction between them and these are the ones yo break when the substance is heated not the covalent ones this explains why you get water vapour not H and O

4 of 4

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all The Periodic Table resources »