1 - Chemical Bonding and Structure

Question 1

What is meant by isoelectric?

Answer 1

Ions with the same electronic configuration - Such as Mg2+ and F-

Question 2

What is evidence for ions?

Answer 2

The migration of ions during electrolysis

Question 3

Define Ionic bonding

Answer 3

The strong electrostatic force of attraction between oppositely charged ions

Question 4

What is the trend of Ionic radius down a group?

Answer 4

Increases down a group as the ions occupy more shells

Question 5

Define covalent bonding

Answer 5

The strong electrostatic attraction between two nuclei and the shared pair of electrons between them.

Question 6

Describe sigma bonds

Answer 6

End on overlaps of S-S orbitals or P-P orbitals

Question 7

Describe Pie bonds

Answer 7

Side on overlaps of P-P orbitals

Question 8

What is a dative covalent bond?

Answer 8

When an orbital with a lone pair of electrons shares both electrons to another atom. Example NH4

Question 9

What is Bond length?

Answer 9

The distance between the nuclei of two atoms that are covalently bonded

Question 10

What is the trend for bond length and bond strength and how do multiple bonds affect this

Answer 10

For similar bonds, the shorter the bond length the greater the bond strength. The more bonds (double or triple) makes the bond shorter. From Cl2-I2 the bond strength decreases as the bond length increases.

Question 11

Do multiple bonds affect shapes of molecules?

Answer 11

No

Question 12

What are the names and angles of the Shapes of Molecules?

Answer 12

2,0 - Linear - 180
3,0 - Trigonal planar - 120
4,0 - Tetrahedral - 109.5
5,0 - Trigonal bipyramidal - 90 and 120
6,0 - Hexagonal - 90 and 180
3,1 - Trigonal pyramidal - 107
2,2 - V-Shaped - 104.5

Question 13

Define Electronegativity

Answer 13

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

Question 14

Describe and explain the trend in electronegativity

Answer 14

Decreases down a group due to effective nuclear charge decreasing with the increase in atomic radii and shielding.
Increases across a period as effective nuclear charge increases due to increase in effective nuclear charge.

Question 15

What is a polar bond and polar molecule?

Answer 15

A polar bond has a permanent dipole

A polar molecule is molecule with one or more polar bonds and unbalanced dipoles due to their shape.

Question 16

What are London Forces?

Answer 16

Intermolecular forces of attraction between instantaneous dipoles and induced dipoles. They exist between all molecules and their strength is determined by the number of electrons and the number of contact points.

Question 17

What are Permanent dipole forces?

Answer 17

Permanent dipole - Permanent dipole interactions - allows attraction and repulsion - overall effect is less than London Forces.

Question 18

What are hydrogen bonds?

Answer 18

Intermolecular forces of attraction in a compound of hydrogen that is covalently bonded to N,O or F and there is a lone pair of electrons on an atom of N, O or F.

Question 19

Explain the trend of boiling temperatures in the hydrogen halides.

Answer 19

The temperatures increase as the number of electrons increase and therefore the London Forces are stronger. HF is the highest however due to the presence of hydrogen bonding.

Question 20

Why does water have anomalous properties?

Answer 20

It has a high melting and boiling point for its number of electrons and its solid is less dense than its liquid.
This is because each water molecule can form two hydrogen bonds on average, increasing its boiling point.

Question 21

What is a solvent?

Answer 21

A substance that in which another substance can dissolve

Question 22

What is a solute?

Answer 22

The substance that dissolves in a substance

Question 23

How does water act as a solvent?

Answer 23

Ionic compounds are soluble in water, the water molecules surround the ions and form electrostatic attractions between them. This is hydration.
Water forms hydrogen bonds with alcohols as they have an OH group.
As the number of carbon atoms on an alcohol increases it becomes less soluble.

Question 24

What is metallic bonding?

Answer 24

The strong electrostatic force of attraction between metal ions (cations) and the delocalised electrons. Solid metals have giant metallic lattice structures with a regular lattice surrounded by delocalised electrons.

Question 25

Structure of Iodine

Answer 25

Diatomic molecule arranged in a simple molecular lattice and is attracted to itself with london forces.

Question 26

Structure of Diamond and graphite

Answer 26

Giant covalent lattices