Periodicity

The periodic table: 

The period and group of an element gives you information about the number of electrons and electron shells an element has. 

Elements in periods: 

- All of the elements within a period have the same number of electron shells. 

e.g in period 2: 

They all have 2 electron shells. 

Elements in groups: 

- All of the elements within a group have the same number of electrons in their outer shell (same number of valance electrons) 

This means that all electrons within the same group have similar properties. 

The group number tells you how many electrons are in the outer shell, eg in group 1, there is 1 electron in the outer shell of each atom of the elements within that group. 

EXCEPT: Group 0 where all of the elements have 8 electrons in their outer shell, apart from helium which only has 2 electrons in it's outer shell. 

Electron configurations:

- The periodic table can also be assorted into s,d,p and f blocks to describe the sub-shells which the electrons of the elements in these groups fall into. 

TRENDS: 

 1. Atomic radius decreases as you move along the period

Explaination: As you move along the period, the nuclear charge increases by +1, this increases the positive charge of the nucleus. This means there is a greater electrostatic attraction between the…