Bonding & Structure

Question 1

What are the 2 anomalous properties of water?

Answer 1

1. Solid ice is less dense than liquid water.
2. Water has a relatively high melting and boiling point.

Question 2

Why does ice float on water?

Answer 2

Hydrogen bonds hold the H2O molecules further apart in ice making it less dense than water so ice floats on water.

Question 3

Why does water have a relatively high melting and boiling point?

Answer 3

The hydrogen bonds in water molecules are the strongest type of intermolecular force so they require a lot of energy to break.

Question 4

What are the 3 physical properties of simple molecular structures? Explain.

Answer 4

1. Low melting and boiling points. Simple molecular -> weak intermolecular forces between molecules -> little energy needed to break. (Actual m.p. and b.p. determined by strength of IMF)
2. Do not conduct electricity at all. No delocalised electrons or mobile ions.
3. Non-polar - not water soluble as cannot form bonds with water. Polar - water soluble as can form bonds with water.

Question 5

Properties of giant ionic lattices? Explain.

Answer 5

1. High m.p. and b.p. -> SEABOCI -> require lots of energy to break forces.
2. Conduct electricity when molten/aqueous. Have mobile ions.
3. Soluble in water. Ions attracted to H2O molecules.

Question 6

Define ionic bond.

Answer 6

Strong electrostatic attraction between oppositely charged ions.

Question 7

Define covalent bond.

Answer 7

Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Question 8

Define dative covalent bond.

Answer 8

One atom provides both electrons needed to form a covalent bond.

Question 9

Which periodic table groups have lone pairs and vacant orbitals?

Answer 9

LP: group 5, 6, 7-
VO: group 3, H+

Question 10

Define electronegativity.

Answer 10

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

Question 11

Define polar bond.

Answer 11

A covalent bond with an unequal share of electrons due to differing electronegativies of the bonding atoms.

Question 12

How do London forces arise?

Answer 12

RUTID:
1. Random movement of electrons leads to
2. Uneven distribution of electrons leads to
3. Temporary dipole on one molecule leads to
4. Induced dipole on another molecule leads to
5. Dipoles attract to form London forces.