Trends In The Periodic Table

Question 1

Atomic radius

Answer 1

Half the distance between the nuclei of two adjacent atoms of the same element joined by a single covalent bond

Atomic radius increased down a group::
As more energy levels are added the atomic radius increases

Atomic radius decreases across a period::
As more protons are added the nuclear charge increases resulting in a greater force of attraction

Question 2

Electronegativity

Answer 2

Measure of the relative attractiveness of an Adam for a shared pair of electrons in a covalent bond

Bonds can be identified by finding the difference of electronegativity

Ionic>1.7>covalent

Non-polar (equal sharing of electrons) <1.0

Polar (unequal sharing of electrons) ~ 1.7

All of this is important to know because it depicts whether it is soluble in water or not

Question 3

First ionisation energy

Answer 3

Minimum energy in kilojoules required to completely remove the most loosely held electron from one mole of gaseous atoms in their ground state

X(g)—e-=X+(g)

Question 4

Screening effect

Answer 4

Innermost electrons shield other electrons from the nuclear charge

Question 5

We activity of alkali metals

Answer 5

Reactivity increases down the group

Ionisation energy and electronegativity decreases down the group

Question 6

Reactivity of halogens

Answer 6

Reactivity decreases down the group

This is due to the decrease in electronegativity