3.1.3 (b&s) covalent bonding

Question 1

what does covalent bonding happen between?

Answer 1

two non metal atoms sharing at least one pair of electrons

Question 2

definition: covalent bonding

Answer 2

a covalent bond is a shared pair of electrons

Question 3

when atoms combine by covalent bonds, what are formed?

Answer 3

molecules

Question 4

what are non bonded pairs of outer electrons on a compound called?

Answer 4

lone pairs of electrons

Question 5

what is the melting/ boiling point like in simple covalent molecules?

why?

Answer 5

low melting/boiling points

because they have weak intermolecular forces between the molecules which are easily broken

Question 6

can simple covalent molecules conduct electricity?

why/why not?

Answer 6

no

because there are no delocalised electrons to carry a charge

Question 7

what does the solubility of simple covalent molecules depend on?

Answer 7

the solubility in water and other solvents depends upon the degree of polarity in the molecule

Question 8

what’s another term for giant covalent structures?

Answer 8

macromolecules

Question 9

what are the two types of carbon macromolecules?

(giant covalent molecules)

Answer 9

graphite and diamond

Question 10

what does the structure of graphite look like?

Answer 10

Question 11

how are the carbon atoms arranged in graphite?

Answer 11

arranged into layers of flat hexagons with each carbon bonded to three other carbon atoms

Question 12

what’s different about the 4th electron in graphite?

Answer 12

it’s delocalised between the layers

Question 13

what are the hexagon layers in graphite bonded together by?

Answer 13

weak van der waals forces

Question 14

what are 5 properties of graphite?

Answer 14

• it’s slippery
• it can conduct electricity
• it’s a low density material
• has a very high melting point
• it’s insoluble

Question 15

how is graphite slippery?

Answer 15

the weak bonds between the layers are easily broken so the hexagon sheets can slide other one another making graphite slippery

Question 16

how can graphite conduct electricity?

Answer 16

contains delocalised electrons which are free to move within each layer

Question 17

how is graphite a low density material?

what can this be used to make?

Answer 17

the layers are relatively far apart compared to the length of covalent bonds making graphite low density

used to make strong lightweight sports equipment

Question 18

what causes graphites very high melting point?

Answer 18

the strong covalent bonds in the hexagon layers

Question 19

why is graphite insoluble?

Answer 19

as the covalent bonds in the hexagon layers are too difficult to break

Question 20

what does the structure of diamond look like?

Answer 20

Question 21

how many other carbons is each carbon atom bonded to?

Answer 21

4

Question 22

how are the atoms arranged in diamond?

Answer 22

in a tetrahedral shape around a central atom forming a macromolecular crystal

Question 23

what are 5 properties of diamond?

Answer 23

• high melting point
• hard
• good thermal conductor
• can’t conduct electricity
• insoluble

Question 24

what causes diamond high melting point?

Answer 24

the strong covalent bonds between carbon atoms throughout the structure

Question 25

how is diamond a good thermal conductor?

Answer 25

as vibrations travel easily throughout the regular lattice structure

Question 26

why can’t diamond conduct electricity?

Answer 26

because there are no delocalised electrons to move and carry a charge

Question 27

what makes diamond insoluble to any solvent?

Answer 27

the covalent bonds are too strong to break