Periodic Table trends

Question 1

What is core charge

Answer 1

a measure of the net attractive force felt by the valence shell electrons towards the nucleus

Question 2

How do you calculate core charge

Answer 2

number of protons in the nucleus - number of electrons in inner shells
OR
group number

Question 3

Atomic radius

Answer 3

half the distance between 2 nuclei of a diatomic molecule (assuming a single covalent bond between 2 identical atoms

Question 4

What influences atomic radius

Answer 4

1) number of occupied energy levels (shells)- (more shells = lower atomic radius)
2) core charge- (higher core charge = valence electrons pulled closer towards the nucleus)

Question 5

What is electronegativity

Answer 5

The strength with which atoms of an element attract electrons when they are chemically combined with another element

Question 6

What increases electronegativity

Answer 6

1) atomic radius is low
2) core charge is high

Question 7

EXAMPLE
Explain why K has a lower electronegativity than Br

Answer 7

K and Br have the same number of occupied energy levels (4) and as the core charge is greater in Br (7+ vs 1+), the atomic radius of Br is smaller than K.

Br also has a greater core charge than K because its nuclear charge is higher however its number of inner electrons is the same.

The smaller atomic radius and higher core charge result in the valence electrons of Br being more strongly attracted to the nucleus than those in a K atom.