Chapter 3.1.3.2 - Nature Of Covalent And Coordinate Bonds

Question 1

How are covalent bonds held together ?

Answer 1

They are held together by electrostatic attraction between the nuclei and the shared electrons

Question 2

Properties of covalent bonding

Answer 2

• Low mp and bp
• Poor conductors of electricity
• Dissolve in water

Question 3

Why are covalent bonds poor conductors of electricity ?

Answer 3

• has no delocalized electrons,

- contains no ions that carry charge

Question 4

When do coordinate bonds form ?

Answer 4

When a lone pair is donated

Question 5

Define lone pair

Answer 5

The atom that is donating the electrons has a pair of electrons this is not being used in a bond

Question 6

Explain coordinate bonding

Answer 6

• It’s a covalent bond
• shares electrons which come from outer-shell
• Pair of electrons are donated by one atom which needs to have a lone pair and lone pairs are non bonded
• Can be polar or non polar because atoms still have electronegativity

Question 7

Difference between coordinate and standard covalent bond ?

Answer 7

Covalent bond

• formed by mutual sharing of electrons
• may be polar or non polar
• compounds are usually insoluble In water
• there should be un paired electrons

Coordinate bonding

• only one atom donates a pair of electrons
• there should be no unpaired electrons
• always polar bcoz it is formed between unlike atoms
• compounds are soluble In water

Question 8

What do the wedges and dashes represent ?

Answer 8

• 3D structure of a molecule
• wedges represent bonds towards the viewer
• dashes lines represent bonds away from the viewer

Question 9

How to identify if an element has a lone pair ?

Answer 9

Valence shell electrons - number of electrons that are bonded
-lone pairs are always in the central element

Question 10

State how coordinate bonds are formed ?

Answer 10

Lone pair is donated

Question 11

State how covalent bonds are formed ?

Answer 11

Shared pairs of electrons

Question 12

How are coordinate bonds represented ?

Answer 12

Using an arrow

Question 13

forms compounds with many other elements.
Fluorine reacts with bromine to form liquid bromine trifluoride (BrF3). State the type of bond between Br and F in BrF3 and state how this bond is formed.
Type of bond
How bond is formed. (2)

Answer 13

• covalent,

- shared pairs of electrons

Question 14

Explain, in terms of bonding, why the boiling point of fluorine is very low. (2)

Answer 14

-van der waals forces between molecules are weak

Question 15

State the type of bond that is formed between the PH3 molecule and the H+ ion. Explain how this bond is formed.
Name of bond
How bond is formed

Steps- draw the structure and check if it has lone pairs or not, mention donation of electrons

Answer 15

• coordinate bonding

- pairs of electrons on PH3 donated to H+

Question 16

State the meaning of the term covalent bond

Answer 16

• Shared pairs of electrons

- between metal and non metal

Question 17

By reference to all the atoms involved explain, in terms of electrons, how Na2S is formed from its atoms

Answer 17

• Electron transfer from Na to S

- 1 electron from each Na atom

Question 18

A bond in AlH4- can be represented by H → Al
Name this type of bond and explain how it is formed.
Type of bond
Explanation

Answer 18

• Coordinate bond,

- transfer of lone pair from H+ to Al

Question 19

Give the name of the type of bond formed when phosphine reacts with an H+ ion. Explain how this bond is formed.
Type of bond
Explanation

Answer 19

• coordinate bond

- transfer of lone pair electrons from P to H+