Intermolecular forces (Electronegativity)

Question 1

Define “electronegativity”

Answer 1

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

Question 2

How does electronegativity change across the periodic table?

Answer 2

• Down the groups, electronegativity DECREASES

- Across the periods, electronegativity INCREASES

Question 3

State the most electronegative elements.

Answer 3

NOF

• Nitrogen (3.0)
• Oxygen (3.5)
• Fluorine (4.0)

Question 4

What types of bonding depend on the electronegativity of a molecule?

Answer 4

Pure covalent, polar covalent and ionic

Question 5

List the electronegativity differences for the types of bonds

Answer 5

• Pure covalent (x < 0.4)
• Polar covalent (0.4 < x < 1.8)
• Ionic (x > 1.8)

POLAR COVALENT - (1.8 < x < 2.1)

Question 6

Define “pure covalent”

Answer 6

The bond between atoms with similar or same electronegativity and has no ionic character.

Vice versa for ionic bonds etc…

Question 7

Displayed here are the electronegativity values for Copper and Bromine. Calculate electronegativity difference and state the type of bond.

Cu - 1.9
Br - 3.0

Answer 7

3. 0 - 1.9 = 1.1
4. 1 is in between 0.4 and 1.8. Therefore, it has a polar covalent bond.

Assume molecules have only 1 atom of each element.