Trends in the periodic Table

Question 1

What is the Atomic Radius trend?

Answer 1

This is the distance from the most outer shell.
When going down a group: the atomic radius increases as an extra shell is added
When going acros: the radius decreases as the electrons are held closer to the nucleus.

Question 2

What is the first ionisation energy trend?

Answer 2

This is the energy neede to remove electrons.
Going down a group: the energy decreases as electrons are further away from the nucleus
Going across: it increases as the e- are held tighter to the nucleus

Question 3

What is the electronegativity trend?

Answer 3

is the tendancy for atoms to attract electrons.
going Down: this decreases due to shielding effect of layered shells
Going across : it increases as the right hand side of the periodic table needs electrons more (Refer to Valency Table)