Electronegativity

Question 1

define electronegativity?

Answer 1

the ability of an atom to attract the pair of electrons in a covalent bond.

Question 2

What affect electronegativity?

Answer 2

nuclear charge
atomic radius
electron shielding

Question 3

What is the most electronegative element?

Answer 3

Fluorine - largest nuclear charge
small atomic radius

Question 4

How do you get a non polar bond?

Answer 4

both bonding elements have the same electronegativities

Question 5

When do you get a polar bond?

Answer 5

Bonding atoms have different electronegativities.

Question 6

What is the strongest type of intermolecular force?

Answer 6

Hydrogen bonding

Question 7

What is the weakest type of intermolecular force?

Answer 7

induced dipole dipole / van der waals forces

Question 8

Describe van der waals’ forces of attraction?

Answer 8

There is a random movement of electrons which leads to a temporary uneven distribution of electrons. This creates a dipole which induces a dipole in its neighbouring molecules.This leads to a temporary dipole dipole attraction.

Question 9

Are van der waals forces stronger in smaller or larger molecules?

Answer 9

Larger because there are more electrons

Question 10

Describe permanent dipole dipole attraction?

Answer 10

• occurs in polar molecules only
  -Polar molecules are attracted to each other
• they are stronger than induced dipole dipole.
  -forces of attraction between dipoles and those of neighbouring molecules.

Question 11

What conditions are needed for hydrogen bonding to occur?

Answer 11

O-H
N-H
F-H

because O N and F are highly electronegative, H nucleus is left exposed.
There is a strong force of attraction between H nucleus and lone pair of electrons on O,N,F

Question 12

Why is ice less dense than liquid water?

Answer 12

in liquid water - hydrogen bonds constantly break and reform as molecules move about
in ice - the hydrogen bond holds the molecules in fixed positions - this makes them slightly further apart in liquid water.