Covalent Bonding - Intro to Back to Basics (1.5)

Question 1

What is a covalent bond?

Answer 1

A covalent bond is a shared pair of electrons between two atoms

Question 2

Explain what happens in covalent bonding

Answer 2

• Occurs between two non-metals

- Atoms need to gain electrons for a full outer energy level so they share electrons

Question 3

What is a coordinate bond?

Answer 3

A coordinate bond (dative covalent bond) is a special type of covalent bond where both electrons are donated from ONE atom

Question 4

Name the two types of covalent structure

Answer 4

• Simple covalent molecules

- Giant covalent structures

Question 5

Describe the structure of simple covalent molecules

Answer 5

A few atoms are covalently bonded to each other to make discreet molecules - the molecules are entirely separate

Question 6

Describe covalent structures

Answer 6

All of the atoms in the structure are covalently bonded to each other

Question 7

Describe how diamond is covalently bonded

Answer 7

Each C atom is covalently bonded to four other carbon atoms

Question 8

Give & explain properties of diamond

Answer 8

• Diamond is very hard and has very high melting point because these bonds are difficult to break
• Can’t conduct electricity because the electrons in the bonds can’t move

Question 9

Describe how graphite is covalently bonded

Answer 9

Forms hexagonal layers, where each C is bonded to 3 others

Question 10

Give & explain properties of graphite

Answer 10

• Soft because the layers can slide over each other

- Can conduct electricity as there is 1 free electron per C which can move

Question 11

Give some examples of allotropes of carbon

Answer 11

Graphite, diamond, fullerene, nanotubes

Question 12

Describe how is a fullerene covalently bonded

Answer 12

Each carbon atom is bonded to 3 others, forming a sphere

Question 13

Give a way that the structure of fullerenes can be useful

Answer 13

Can be used as a cage to trap molecules or deliver drugs to areas of the body

Question 14

Describe how nanotubes are covalently bonded

Answer 14

Made of hexagonal layers of C, arranged into a tube

Question 15

Give the properties & uses of nanotubes

Answer 15

• Can conduct electricity

- Can be used for drug delivery and as a miniature reaction vessels

Question 16

Give two structures that are similar to diamond

Answer 16

Silicon & silicon dioxide

Question 17

Give two common polymers

Answer 17

Polyethylene (plastic) & polyamides (proteins)

Question 18

Give the properties of simple covalent molecules

Answer 18

• Do not conduct electricity (electrons are trapped in bonds)
• Have low melting & boiling points due to the weak intermolecular forces (between molecules)