1covalent bonding

Question 1

non metal atoms can share electrons with

Answer 1

other non metal atoms to obtain a full outer shell of electrons

Question 2

when non metal atoms share pairs of electrons they form

Answer 2

covalent bonds

Question 3

covalent bonds between atoms are

Answer 3

very strong

Question 4

when two or more atoms are chemically bonded together they

Answer 4

form molecules

Question 5

shared electrons are called

Answer 5

bonding electrons and occur in pairs

Question 6

simple covalent molecules do not

Answer 6

conduct electricity as they do not contain free electrons

Question 7

covalent bonding in terms of electrostatic attraction

Answer 7

There is a strong electrostatic attraction between the shared pair of electrons and the nuclei of the atoms involved, since the electrons are negatively charged and the nuclei are positively charged

Question 8

simple molecular structures have

Answer 8

covalent bonds joining the atoms together, but intermolecular forces act between neighbouring molecules

Question 9

covalent bonds- mp/bp

Answer 9

they have low melting and boiling points as there are only weak intermolecular forces acting between the molecules

Question 10

as the molecules increase in size

Answer 10

the intermolecular forces also increase as there are more electrons available- this causes melting and boiling point to increase

Question 11

as the relative molecular mass of a substance increases the melting/boing point will too- why

Answer 11

An increase in the relative molecular mass of a substance means that there are more electrons in the structure, so there are more intermolecular forces of attraction that need to be overcome when a substance changes state
So larger amounts of heat energy are needed to overcome these forces, causing the compound to have a higher melting and boiling point

Question 12

covalent bonds are poor conductors of electricity as

Answer 12

there are no free ions or electrons to carry the charge

Question 13

most covalent compounds do not conduct electricity at all so are

Answer 13

insulators

Question 14

giant covalent structures have

Answer 14

a huge number of non metal atoms bonded to other non metal atoms via strong covalent bonds- these structures are called giant lattices and have a fixed ratio of atoms in the overall structure

Question 15

diamond and graphite are

Answer 15

allotropes of carbon

Question 16

allotropes

Answer 16

different atomic or molecular arrangements of the same element in the same physical state

Question 17

both diamond and graphite only

Answer 17

contain carbon atoms but due to the differences in bonding arrangements they are physically completely different

Question 18

in diamond each carbon atom

Answer 18

bonds with four other carbons- forming tetrahedron

Question 19

properties of diamond

Answer 19

It does not conduct electricity
It has a very high melting point
It is extremely hard and has a density of 3.51 g / cm3 – a little higher than that of aluminium

Question 20

the four covalent bonds of diamond are

Answer 20

very strong and extend in a giant lattice so a very large amount of heat energy is needed to break the lattice

Question 21

diamonds hardness makes it very useful for

Answer 21

purposes where extremely tough material its required

Question 22

diamonds are used for

Answer 22

jewellery and coating blades in cutting tools

Question 23

the cutting edges of discs used to cut bricks and concrete as well as heavy duty drill bits and tooling equipment are

Answer 23

tipped with Dimond

Question 24

in graphite each carbon atom is

Answer 24

bonded to three others forming layers of hexagons, living one free electron per carbon atom

Question 25

graphite can conduct electricity because

Answer 25

the free electrons migrate along the layers and are free to move and carry charge

Question 26

covalent bonds within layers are very strong but

Answer 26

the layers are attracted to each other by weak intermolecular forces so the layers can slide over each other making graphite soft and slippery

Question 27

properties of graphite

Answer 27

It conducts electricity and heat
It has a very high melting point
It is soft and slippery and less dense than diamond (2.25 g / cm3)

Question 28

fullerenes are

Answer 28

a group of carbon allotropes which consist of molecules that form hollow tubes or spheres

Question 29

fullerenes can be used to

Answer 29

trap other molecules by forming around the target molecule and capturing it, making them useful for targeted drug delivery systems

Question 30

fullerenes have a

Answer 30

huge surface area and are useful for trapping catalyst molecules onto their surfaces making them easily accessible to reactants so catalysis can take place