Chemical Bonding

Question 1

what is an ion

Answer 1

a charged atom or group of atoms

Question 2

what happens when an atoms loses one or more electrons

Answer 2

it becomes a positive ion called a cation

Question 3

why do elements in group 1 form ions with a charge of +1

Answer 3

because they lose one electron to have a stable electron arrangement

Question 4

what happens when an atom gains one or more electrons

Answer 4

they become a negative ion called a anion

Question 5

why does the gain of an electron from an atom always produce a negative ion

Answer 5

there are more negative charges than positive so the atom becomes a negative ion

Question 6

what is an ionic bond

Answer 6

the electrostatic force of attraction between the positive and the negative ions as a result of electron transfer

Question 7

what is an ionic bond formed between

Answer 7

a metal and a non-metal

Question 8

what is the structure of ionic compounds

Answer 8

a giant ionic lattice

Question 9

how are ions held together in ionic compounds such as NaCl

Answer 9

the strong electrostatic attractions between the positive and negative ions hold the ions together in sold NaCl

Question 10

what are the properties of ionic compounds

Answer 10

they have high melting/boiling points
conduct electricity when melted or dissolved in water
mostly all ionic compounds are soluble in water
solids at room temperature

Question 11

why do ionic compounds have high melting/boiling points

Answer 11

they have a giant ionic lattice with strong electrostatic forces of attractions between the positive and negative ions. A large amount of energy is needed to break the strong ionic bonds and make the ions mobile

Question 12

why do ionic compounds only conduct electricity when molten or dissolved in water

Answer 12

when they are melted or dissolved in water, the ions can move and carry the charge but when the compounds are solid the ions can’t move and just vibrate around their fixed positions

Question 13

what is a covalent bond

Answer 13

a pair of electrons shared between two atoms

Question 14

what is a covalent bond formed between

Answer 14

two non-metals

Question 15

what is the structure of covalent compounds

Answer 15

a simple molecular strucutre

Question 16

why do larger molecules have higher boiling points than smaller molecules

Answer 16

larger molecules have more intermolecular forces

Question 17

what are the properties of covalent compounds

Answer 17

they have low boiling points
they don’t conduct electricity
often insoluble in water but soluble in organic solvents

Question 18

why do covalent compounds have low boiling points

Answer 18

they have a simple molecular structure. They are made up of small molecules with weak forces between the molecules and little energy is needed to break these weak intermolecular forces

Question 19

why do covalent compounds not conduct electricity

Answer 19

there are no free electrons as the outer electrons are all fixed in covalent bonds

Question 20

why does the metal calcium form an ionic bond but the non-metal silicon forms covalent bonds

Answer 20

a calcium atom can lose two electrons to obtain a stable electron arrangement. Silicon cannot lose four electrons or gain four electrons but has to share four electrons

Question 21

what are allotropes

Answer 21

different forms of an element in the same physical state

Question 22

what are the allotropes of carbon

Answer 22

diamond, graphite, graphene and fullerene

Question 23

what is the structure of diamond

Answer 23

giant covalent lattice with strong covalent bonds between the atoms

Question 24

why does diamond have a high melting point

Answer 24

many bonds need to be broken to melt it and this needs a large amount of energy

Question 25

why is diamond a hard substance

Answer 25

it has a giant covalent lattice with strong covalent bonds between atoms that extend throughout the lattice

Question 26

why does diamond not conduct electricity

Answer 26

there are no free electrons as each carbon atom is covalently bonded to four other carbon atoms

Question 27

what are the uses of diamond

Answer 27

jewellery, glass cutters, drill bits

Question 28

what is the structure of graphite

Answer 28

giant covalent lattice

Question 29

what are the properties of graphite

Answer 29

soft and slippery conducts electricity high melting point

Question 30

why is graphite soft and slippery

Answer 30

graphite has layers of carbon atoms and there are weak forces between the layers so the layers can slide over each other

Question 31

why does graphite conduct electricity

Answer 31

as each carbon atom only forms 3 bonds, each carbon atom has one free electron so graphite has delocalised electrons which move along the layers and carry the charge

Question 32

why does graphite have a high melting point

Answer 32

graphite has a giant covalent lattice with strong covalent bonds between the atoms therefore many bonds need to be broken to melt it and this needs a large amount of energy

Question 33

what are the uses of graphite

Answer 33

electrodes in pencils as a lubricant

Question 34

what is the structure of graphene

Answer 34

giant covalent lattice with strong covalent bonds between the atoms

Question 35

what are the properties of graphene

Answer 35

high melting points conducts electricity thin and light good electrical conductor

Question 36

why does graphene have a high melting point

Answer 36

it has a giant covalent lattice with strong covalent bonds between the atoms and many bonds need to be broken to melt it and this needs a large amount of energy

Question 37

why does graphene conduct electricity

Answer 37

as each carbon atom only forms 3 bonds, each carbon atom has one free electron so graphene has delocalised electrons. These delocalised electrons move along the layers and carry the charge

Question 38

what is the strucutre of fullerene

Answer 38

molecular structure

Question 39

why does fullerene have a low melting point

Answer 39

in fullerene there are weak forces between the molecules. Little energy is needed to break these weak intermolecular forces and melt fullerene so it has a low melting point

Question 40

why doesn't fullerene conduct electricity

Answer 40

fullerene has delocalised electrons so it conducts electricity across the surface of the molecule however, fullerene is a poor conductor as there is no movement of electrons between the molecules

Question 41

what are fullerenes used in

Answer 41

aircraft, space and car industires

Question 42

what is graphene used in

Answer 42

electronics and composites

Question 43

what type of bond is in metalsd

Answer 43

metallic bond

Question 44

what is metallic bonding

Answer 44

the electrostatic force of attraction between the positive ions and the delocalised electrons

Question 45

what is the strucutre in metals

Answer 45

giant metallic latitce

Question 46

why are metals good conductors of electricity when solid

Answer 46

delocalised electrons flow through the metal structure and carry the charge

Question 47

why are metals malleable

Answer 47

ina metal the ions are held in a lattice structure with no fixed bonds. Therefore when a metal is bent or hammered the layers of ions slide over each other allowing the metal to change its shape without breaking the structure

Question 48

why do metals have a high melting point

Answer 48

they have a giant metallic lattice. there are strong electrostatic forces of attraction between the metal ions and the delocalised electrons and a large amount of energy is needed to break the strong attractive forces.