Periodic Trends (Test 2)

Question 1

Define Atomic Radius

Answer 1

Atomic radius is the SIZE of the atom: includes the nucleus, electrons & empty space.

It is dependent on:
  - No. of electrons
  - Position of electrons in 
    shells
  - Charge on nucleus

Question 2

Describe the trend for Atomic Radius

Answer 2

Down a group:
Atomic radius increases due to the outershell is away from radius (as we add another electron shell).

Across a period:
Atomic radius decreases (as the number of protons in the nucleus & electrons in the valence shell increases, the electrostatic attraction between the protons and the electrons increases and attracts the valence shell closer to the nucleus)
BUT groups 18 is slightly larger!

Question 3

Define electronegativity

Answer 3

Electronegativity is the atoms ability to attract electrons in a chemical bond.

• Fluorine is the most electronegative and Francium is the least electronegative

Question 4

Define Ionisation energy

Answer 4

I.E is energy required to remove 1 moles of electrons from 1 mole of atoms, in gaseous phase.

1st Ionisation energy: Energy required to remove the first electron.

Question 5

Describe the trend for Ionisation Energy

Answer 5

Down a group:
Ionic ionisation decreases as the increase in no. of electron shells means the outer most electron is further from electrostatic attraction of the protons & less energy is needed to remove it.

Across a period:
Ionic ionisation increases as you move across a period the no. of protons in the nucleus & electrons in the same valence shell increases & the increased no. of protons have a greater electrostatic attraction on the electrons so the energy required to remove an electron is increased.

Question 6

Describe the trend for Electronegativity

Answer 6

Down a group:
Electronegativity decreases as outer shell of electrons are further from nucleus (Also A.R. increases) & electrostatic attraction between ‘+’ nucleus & valence elec. decreases causing electrons to be less strongly attracted in chemical bond.

Across a group:
Electronegativity increases as outer shell is close to positive nucleus (A.R decreases) & electrostatic attraction between ‘+’ nucleus & ‘-‘ valence electrons increases. Causing electrons to be more tightly attracted to an atom in a chemical bond.