1.3 Bonding

Question 0

What type of bonding is involved in NaCl?

Answer 0

Ionic bonding

Question 1

Define dative bonding.

Answer 1

A covalent bond in which both electrons are donated by the same atom

Question 2

Give an example of a permanent dipole-dipole bond.

Answer 2

H2O, HCl, NH3

Question 3

What is the strongest type of bond?

Answer 3

Covalent

Question 4

Describe the solubility of ionic compounds.

Answer 4

Ionic compounds tend to dissolve in water. Water molecules are polar and pull the ions away from the ionic lattice, causing it to dissolve.

Question 5

Suggest why simple covalent compounds have low melting points.

Answer 5

They have weak intermolecular forces which are easily broken

Question 6

Give another name for dative bonding.

Answer 6

Co-ordinate bonding

Question 7

Describe valence-shell electron-pair repulsion theory.

Answer 7

As lone pairs of electrons have greater angles between them than in bonding pairs, the shape of a molecule can be determined by the number and type of charge clouds on the valence shell.

Question 8

What is electronegativity?

Answer 8

Electronegativity is the ability or tendency of an element to attract the electron density in a covalent bond towards itself.

Question 9

Name the 3 main types of intermolecular forces. State which are the weakest and strongest.

Answer 9

• Induced dipole-dipole (Van der Waals) —Weakest
• Permanent dipole-dipole
• Hydrogen bonding — Strongest

Question 10

What is the bond angle between electron pairs in a trigonal pyramidal molecule?

Answer 10

107

Question 11

Name the type of structure a molecule will have if it has 6 bonding pairs on the central atom.

Answer 11

Octahedral

Question 12

Explain why ionic compounds conduct electricity when molten but not when solid.

Answer 12

The ions in the liquid are free to move and they carry a charge. In a solid they’re fixed in position by strong ionic bonds

Question 13

Explain why graphite is a conductor.

Answer 13

Each carbon atom only makes 3 covalent bonds, not 4, so for every atom there is a delocalised electron which can carry charge

Question 14

How many bonding pairs of electrons are on the central atom of a tetrahedral molcule?

Answer 14

4

Question 15

Explain why ice is less dense than water.

Answer 15

Ice has more hydrogen bonds than water, and the hydrogen bonds are quite long meaning the H2O molecules in ice are further away from each other than they are in water. This makes ice less dense than water.

Question 16

Give an example of a bent/non linear molecule and state its bonding angle.

Answer 16

Water (H2O)

104.5

Question 17

How many electron pairs and lone pairs does a trigonal pyramidal molecule have?

Answer 17

3 electron pairs and 1 lone pair

Question 18

How is a dipole formed?

Answer 18

A dipole is caused by a shift in electron density in the bond due to differences in electronegativity. There will be a difference in charge between the two atoms (one is slightly positive and one is slightly negative).

Question 19

What is the most electronegative element?

Answer 19

Fluorine

Question 20

Hydrogen bonding will only occur when hydrogen is covalently bonded to which three elements?

Answer 20

Fluorine, nitrogen and oxygen

Question 21

Which factors affect the melting point of metals?

Answer 21

• Number of delocalised electrons

- Size of the metal ion

Question 22

Why are metals good thermal conductors?

Answer 22

The delocalised electrons are free to move and can pass kinetic energy to each other.

Question 23

What name is given to a molecule with 5 electrons pairs? Give an example.

Answer 23

Trigonal bipyramidal e.g PCl5

Question 24

What is the bonding angle between a tetrahedral molecule e.g NH4+?

Answer 24

109.5