Unit 1-Bonding Topic 3

Question 1

What is an ionic bond?

Answer 1

Ionic bond is the electrostatic attraction between positive and negative ions.

Question 2

What is meant by an ionic lattice?

Answer 2

A lattice is a regular arrangement of ions where each positive ion is surrounded by negative ions and each negative ion is surrounded by positive ions.

Question 3

Explain the physical properties of ionic compounds:

1. melting point and boiling point
2. solubility (water molecules surround ions)
3. electrical conductivity

Answer 3

1. Ionic compounds have high melting and boiling points because strong ionic bonds must be broken in order to break down the lattice.
2. Tend to be soluble in water.
3. Ionic compounds conduct electricity only when molten or in solution, due to the breakdown of the lattice resulting in the ions being free to move

Question 4

What is a covalent bond?

Answer 4

In a covalent bond, the shared pair of electrons is attracted to the nuclei of the two bonded atoms.

Covalent bonds are usually between non metals.

Question 5

Draw a diagram, showing all outer electrons, to represent a molecule of Arsenic Chloride, AsCl₃.

Answer 5

Question 6

What are the two types of covalent structures??

Answer 6

Covalent substances can form either discrete molecular or giant network structures.

Question 7

Which elements exist as diatomic molecules?

Answer 7

HINFOClBr

Hydrogen, Iodine, Nitrogen, Fluorine, Oxygen, Chlorine and Bromine

Question 8

Name these shapes of molecules.

Answer 8

1. Linear 2. angular(Bent)
2. trigonal pyramidal 4. tetrahedral.

Question 9

Explain the physical properties of discrete molecular covalent compounds:

1. melting point and boiling point
2. solubility (water)
3. electrical conductivity

Answer 9

1. Covalent molecular substances have low melting and boiling points as only weak forces of attraction between molecules are being broken.
2. Covalent molecules tend to be insoluble in water but soluble in covalent type solvents.
3. Covalent molecules never conduct except carbon graphite.

Question 10

Explain the physical properties of covalent network compounds:

1. melting point and boiling point
2. solubility (water molecules surround ions)
3. electrical conductivity

Answer 10

1. Giant covalent network structures have very high melting and boiling points because the network of strong covalent bonds must be broken.
2. Covalent molecules tend to be insoluble in water but soluble in covalent type solvents.
3. Covalent molecules never conduct except carbon graphite.

Question 11

Describe the bonding in metals.

Answer 11

In metallic bonding, the outer electrons are delocalised (free to move). This produces an electrostatic force of attraction between the positively charged metal ions, and the negatively charged delocalised electrons.

Question 12

Explain the physical properties of metals.

1. Melting and boiling points
2. Conductivity of electricity

Answer 12

1. Metals are held together by strong forces and have high melting and boiling points.
2. The ability of metals to conduct electricity stems from their delocalised electrons. As these are free to move, an electrical current can flow through metallic materials.

Question 13

Which type of bonding matches each line in the table?

Answer 13

A= Discrete covalent molcular

B = Covalent network

C = Ionic

D = Metallic

Question 14

Which type of bonding is represented by each diagram?

Answer 14

A = Metallic

B = Discrete covalent molecular

C = Covalent network

D = Ionic

Question 15

How are Ionic bonds held together by?

Answer 15

the electrostatic attraction between positive and negative ions.

Question 16

Metal ions are ______ charged

Answer 16

Positively

Question 17

Non-metal ions are ____________ charged

Answer 17

Negatively

Question 18

Metal atoms donate electrons to form positively charged ions. So non metal atoms gain electrons to __________

Answer 18

form negatively charged ions

Question 19

Ionic compounds only conduct when molten or in solution as the

Answer 19

ions are free to move