Periodic Trends

Question 1

Explain the trends in atomic Radius:

Answer 1

Atomic Radius increases as you go down a group.

• This is due to the higher number of electrons shells as the number of electrons present increase as you go down the group.
• At the start of each new period electrons start filling the next outermost shell each further away from the nucleus.

Atomic Radius decreases as you go from left to right in a period.

• This is due to the increase in nuclear charge in the atom.
• More protons result in a higher positive nuclear charge, increasing the attraction it has on the electrons pulling them closer.

Question 2

Explain Ionization energy:

Answer 2

First ionization energy measures the minimum amount of energy required to remove the single most loosely bound electron from an atom in a neutral gaseous state.

Increases from left to right in any given period:

• Due to a decreased atomic radius and increasing nuclear charge the valence electrons are more strongly attracted to the nucleus hence more energy is required to overcome this.

Decreases as you go down a group:

• Due to electrons increased distance from the nucleus and a greater number of electron shells, the positive nuclear charge is shielded and has a lesser effect on the valence electrons hence less energy is needed to overcome this.

Question 3

Electronegativity:

Answer 3

The ability of a atom in a molecule to attract electrons to itself.

Increases left to right in a period.

Decreases down a group.