Bonding

Question 1

What is ionic bonding?

Answer 1

Strong electrostatic forces of attraction between oppositely charged ions.

Question 2

Why do ionic compounds have high mp/bps?

Answer 2

They have strong electrostatic forces which take lots of energy to break.

Question 3

When do ionic compounds conduct electricity?

Answer 3

When molten or dissolved in a solvent, as the ions are mobile and can carry charge.

Question 4

What is simple molecular bonding?

Answer 4

Strong covalent bonds between atoms, but they have weak van der waals forces of attraction between molecules.

Question 5

Do lone pairs exist in simple covalent bonding?

Answer 5

No, all electrons are involved in bonding.

Question 6

When can simple molecular molecules conduct electricity?

Answer 6

Never - all of the electrons are used in bonding, so can’t move / carry charge

Question 7

Why do simple molecules substances have a low mp/bp?

Answer 7

They have weak Van der Waal intermolecular forces which do not require a lot of energy to break

Question 8

What is macromolecular covalent bonding?

Answer 8

Lattice of many atoms held together by strong covalent bonds.

Question 9

Why do substances with macromolecular covalent bonds have high/low molecular/bps?

Answer 9

It takes a lot of energy to overcome many strong covalent bonds.

Question 10

Describe the structure of diamond.

Answer 10

3D tetrahedral structure of C atoms, where each C is bonded to 4 other carbon atoms

Question 11

Describe the structure of graphite.

Answer 11

• each carbon is bonded to 3 other Cs
• weak VDWs between layers so layers can slide over each other
• one electron from each carbon is delocalised so can carry charge and conduc electricity

Question 12

What is metallic bonding?

Answer 12

Bond between metals, creating a lattice of metal ions kept together with a sea of delocalised electrons. (So can carry charge)
Layers can slide over each other, malleable.

Question 13

Why do metallic compounds have a high mp/bp?

Answer 13

They have strong forces of attraction between the metal ions and the delocalised electrons

Question 14

What affects the strength of metallic bonds?

Answer 14

Charge of metal ions - the higher the charge, the stronger the bond as there are more delocalised electrons s and the force of attraction will get stronger

Question 15

What is electronegativity?

Answer 15

The ability of an atom to attract the pair of electrons within a covalent bond

Question 16

What 3 things affect electronegativity?

Answer 16

• nuclear charge
• atomic radius
• shielding

Question 17

What is a polar molecule?

Answer 17

A covalent molecule where one element is more electronegative than the other, so there are partial charges on the elements in the compound.

Question 18

What is a non-polar compound?

Answer 18

A covalent compound where both bonding elements have similar or the same electronegativity.

Question 19

What are the types of intermolecular forces?

Answer 19

Hydrogen bonding, Induced dipole-dipole, and permanent dipole-dipole

Question 20

What is the order of strength of intermolecular forces? (Low to high)

Answer 20

Induced dipole-dipole → permanent dipole-dipole → hydrogen bonding.

Question 21

What is Van der Waals forces?

Answer 21

Temporary dipoles are created by the random movement of electrons, which induces a dipole in a neighbouring molecule due to the repulsion of negative charges. This becomes a temporary, induced dipole.

Question 22

When are VDWs stronger?

Answer 22

Larger molecules, as there are more electrons

Question 23

What is a permanent dipole-dipole?

Answer 23

Polar molecules have permanent dipoles, forces of attraction between dipoles and that of neighbouring molecules

Question 24

When does H bonding occur?

Answer 24

in O-H, N-H or F-H bonds, with a lone pair on the O, N or F.

Question 25

Why does H bonding occur?

Answer 25

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

Question 26

Why is ice less dense than liquid water?

Answer 26

Liquid water has H bonds which are constantly breaking and reforming as the molecules move around.
In ice, the H bonds are slightly further apart than in liquid water as they are held in fixed positions.

Question 27

What is a dative (co-ordinate) covalent bond?

Answer 27

Formed when an electron deficient atom accepts a lone pair of electrons from another atom or ion.

Question 28

How is a dative covalent bond represented?

Answer 28

→

Question 29

What does the Electron Pair Repulsion Theory state?

Answer 29

Electron pairs will take positions as far away from each other as possible, to minimise repulsion between them.

Question 30

What type of electron pair is the most repulsive?

Answer 30

Lone pairs have the strongest repulsion.