The term periodicity is used to describe trends in the Periodic table, either going down a group or along a period. Period 3 covers elements from the s-block (so called because they are filling the 3s orbital) and the p-block (filling the 3p orbital), metals, metalloids and non-metals. This collection of posts covers everything you need to know, the physical and chemical trends of both the elements and compounds of Period 3.
Explaining the trend in atomic radius across Period 3
The atomic radius decreases across Period 3 (and we see the same pattern across all periods) because there is an increase in effective nuclear charge as we move from one element to the next.
But how do you measure the radius of an atom?
Properties of Period 3 elements
An explanation of the trends in melting point and structure, ionisation energy and their chemical properties.
Explaining trends in the oxides of Period 3 elements
An explanation of the trends in bonding and structure, and their chemical properties.