3 - Bond polarity

Question 1

Define ‘electronegativity’

Answer 1

The power of an atom to attract negative charge towards itself within a covalent bond

Question 2

Why does electronegativity increase along a period?

Answer 2

• Atomic radius of atoms decrease as electrons are pulled in more
• Same amount of shielding

Question 3

Why does electronegativity decrease down a group?

Answer 3

• Distance between outer electrons and nucleus increases
• Shielding increases

Question 4

What is the most electronegative element?

Answer 4

Fluorine (F₂)

Question 5

How does the difference in electronegativity affect the polarity of a covalent bond?

Answer 5

The bond will become more polar as the difference in electronegativity increases

Question 6

HCl is a polar molecule. How?

Answer 6

Cl is more electronegative than H so it pulls electrons towards itself in a covalent bond, resulting in an uneven distribution of electrons making it polar

Question 7

What symbols do we use to show polarity in a molecule?

Answer 7

• δ+ next to the least electronegative element
• δ- next to the most electronegative element

Question 8

Why do some molecules with polar bonds not have a permenant dipole?

Answer 8

The bonds are arranged symmetrically which cancels out the dipoles