Unit 1 - Covalent & Ionic Bonding

Question 1

Why do atoms form bonds?

Answer 1

To achieve a full stable electron arrangement.
(Like noble gases)

They do this by either sharing or transfering electrons.

Question 2

When are covalent bonds formed?

Answer 2

Formed when elements SHARE Electrons.

Question 3

What elements USUALLY form to make covalent bonds?

Answer 3

USUALLY formed between NON-METAL elements.

Question 4

Covalent bonds in elements - diatomic elements

Answer 4

Some non metal elements join together in twos. They share electrons to have full outer shells.

They are Called DIATOMIC ELEMENTS.

Question 5

What are the diatomic elements

Magic 7

Answer 5

Hydrogen - H2
Nitrogen - N2
Oxygen - O2
                                     (2 should be small at bottom right)
Fluorine - F2
Chlorine - Cl2 
Bromine - Br2
Iodine - I2

Question 6

What are diatomic elements?

Answer 6

Some non-metal elements join together in twos. They share electrons to have full outer shells.

Examples
Hydrogen- H2
Nitrogen- N2
Oxygen - O2

(2 should be small at bottom)

Question 7

Covalent bonds

Answer 7

Atoms share electrons so the atoms are now stable.

Between 2 or more non metal atoms.

A covalent bond is an electrostatic force of Attraction between the positive nuclei and the shared electrons.

Question 8

What are ions?

Answer 8

An ion is an atom or molecule with a net charge due to the loss or gain of one or more electrons.

Question 9

How do atoms form bonds?

Answer 9

Atoms form bonds by either sharing or transferring electrons.

Question 10

What are the shapes of molecules?

Answer 10

Linear molecule
Angular molecule
Trigonal pyramidal
Tetrahedral

Question 11

Ionic bonds definition

Answer 11

An ionic bond is an electrostatic force of attraction between positive and negative ions.

Question 12

How are ionic bonds formed?

Answer 12

Ionic bonds are formed when atoms TRANSFER electrons.

Usually a metal and a non metal atom.

Question 13

What atoms form ionic bonds?

Answer 13

USUALLY metal and non-metal atoms

Non metals atoms gain the electrons (- charges)
Metal atoms lose electrons (+ charges)

Question 14

Bonding structures (4)

Answer 14

Covalent molecule

Covalent network

Ionic lattice

Metallic lattice

Question 15

When are ionic bonds formed?

Answer 15

Formed when atoms TRANSFER electrons.

USUALLY formed between metal and non-metal atoms.

Question 16

Ionic bonds - properties

Answer 16

Always solid at room temperature

high melting and boiling points because of the strong ionic bonds between the ions.

Tend to dissolve in water

Question 17

Covalent bonds - properties

Answer 17

Can be any state at room temperature

Tend to be insoluble in water

Low boiling and melting points

Poor conductors of heat and electricity

???

Question 18

Ionic bonds - structure

Answer 18

Lattice structure

Conducts when in a solution and molten.

Question 19

Covalent bonds - structure

Answer 19

Network structure
- high melting point

Molecule
- low melting point

(Never conducts electricity)

Question 20

The different types of bonds

Answer 20

1. Ionic lattice
2. Metallic lattice
3. Covalent molecule
4. Covalent network

Question 21

Covalent network- properties

Answer 21

Low melting point ?
Low boiling point ?

Weak intermolecular forces ONLY hold the molecules as solids

NO COVALENT BONDS ARE BROKEN WHEN MELTING OR BOILING

Do not conduct
Usually insoluble in water

Non-metals
Very high melting point ???
Very high boiling point 
Strong and hard
Insoluble in water 
Do not conduct - except for graphite

Question 22

Ionic bonds structure

Answer 22

Ionic compounds always have giant ionic lattice structures. The ions form a closely packed regular lattice.

There are very strong electrostatic forces of attraction between oppositely charged ions.

Question 23

Covalent compounds shapes

Answer 23

Linear

Angular

Trigonal pyramidal

Tetrahedral

Question 24

Covalent molecule - properties

Answer 24

Covalent molecules are small molecules with strong covalent bonds within the molecule but weak intermolecular forces between molecules.

• low melting and boiling points because of the weak intermolecular forces (which are broken easily during these state changes). (*no covalent bonds are broken when melting or boiling)
• this is also why they are GASES at room temperature.
• Cannot conduct electricity because they have no changed particles which are free to move.
• insoluble in WATER

Question 25

Covalent network - properties

Answer 25

A covalent network is one giant structure made up of very strong covalent bonds.

• VERY high melting and boiling points because they have very strong covalent bonds which would require alot of energy to break.
• CANNOT conduct electricity (except for graphite)
• insoluble due to their large size.

Question 26

Ionic lattice properties

Answer 26

• high melting and boiling points because they contain strong ionic bonds which must be broken in order to change state (and to break up lattice structure)
• cannot conduct as a solid because the charged particles are not free to move.
• can conduct as a liquid or in solution/molten because their charged particles (ions) are free to move towards oppisitely charged electrodes.
• soluble in water because as they dissolve the lattice structure breaks up so the ions are free to move and be surrounded by water molecules.

Question 27

What elements form giant covalent network structures?

Answer 27

Carbon in the form of graphite or diamond.

Boron

Silicon