Ionic and Covalent Bonding

Question 1

Describe the formation of cations.

Answer 1

when an atom loses electron(s)

Question 2

Are metals always cations or anions?

Answer 2

cations

Question 3

What is a cation?

Answer 3

positively charged ions

Question 4

What is an anion?

Answer 4

negatively charged ions

Question 5

Describe the formation of anions.

Answer 5

when an atom gains electron(s)

Question 6

What is the relationship between group number and the charge of ions formed from that group?

Answer 6

usually, elements form cations which charge = group number
usually, elements form anions which charge = 8 - group number
(transition metals have variable oxidation numbers)

Question 7

What are the oxidation numbers of transition metals?

Answer 7

variable oxidation numbers

Question 8

What type of elements have variable oxidation numbers?

Answer 8

transition elements

Question 9

What is an ionic bond?

Answer 9

a strong electrostatic attraction between oppositely charged ions

Question 10

Describe the properties of ionic compounds.

Answer 10

• high melting points and boiling points
• good electrical conductivity when aqueous or molten and poor when solid

Question 11

Describe the giant lattice structure of ionic compounds.

Answer 11

a regular arrangement of alternating positive and negative i ons

Question 12

Ionic compounds are arranged in…

Answer 12

giant lattice structures

Question 13

Ionic bonds are formed between _____.

Answer 13

metals and non-metals

Question 14

Metals and non-metals form…

Answer 14

ionic bonds

Question 15

Why do ionic substances have high melting/boiling points?

Answer 15

electrostatic forces holding ions together are very strong, a lot of energy needed to separate the ions

Question 16

Why do ionic substances only conduct when molten or aqueous, not solid?

Answer 16

• ions in solid unable to move freely (conduction of electricity occurs when ions can move freely, carrying charge)
• in molten/aqueous solution, ions are free to move and carry charge

Question 17

When is a covalent bond formed?

Answer 17

when a pair of electrons is shared between atoms leading to noble gas electronic configurations

Question 18

What is a covalent bond?

Answer 18

a shared pair of electrons

Question 19

A covalent bond forms between ______.

Answer 19

two non-metals

Question 20

Two non-metals bond ______.

Answer 20

covalently

Question 21

What are properties of simple molecular compounds (covalent)?

Answer 21

• low melting/boiling points
• poor electrical conductivity

Question 22

Why do simple covalent compounds have low melting/boiling points?

Answer 22

weak intermolecular forces between molecules

Question 23

Why do simple covalent compounds not conduct electricity?

Answer 23

no overall charged particles in molecules which can move freely through the structure

Question 24

In covalent molecules, how does size affect melting/boiling points?

Answer 24

the larger the molecule, the higher the melting/boiling point: greater number of weak intermolecular forces between molecules, which need more energy
to overcome

Question 25

Describe the structure of diamond.

Answer 25

- macromolecule
- each C atom shares 1 electron with four other C atoms, making a repeating network of covalently bonded C atoms

Question 26

Describe the structure of graphite.

Answer 26

• layered hexagonal arrangement: each layer is a macromolecule
• layers held together by many weak intermolecular forces
• three of the electrons from each C atom are in covalent bonds
• fourth electron leaves atom, forming a layer of delocalised electrons above the atoms

Question 27

Graphite and diamond are both made out of which element?

Answer 27

carbon

Question 28

Graphite and diamond are both ______ structures.

Answer 28

giant covalent

Question 29

Name two giant covalent structures.

Answer 29

graphite and diamond

Question 30

Why is graphite soft and slippery?

Answer 30

layers slide over each other (weak intermolecular forces)

Question 31

Why is graphite used as a lubricant?

Answer 31

it is soft and slippery because its layers slide over one another

Question 32

Graphite has lots of layers that can slide over one another. Which property of graphite results from this structure?

Answer 32

soft and slippery

Question 33

Why is graphite used as an electrode?

Answer 33

excellent electrical conductor, inert and high melting/boiling points

Question 34

Why is diamond used in cutting tools?

Answer 34

nothing is harder than diamond: it is made up of many strong covalent bonds in a giant structure

Question 35

1 use of diamond

Answer 35

cutting tools

Question 36

2 uses of graphite

Answer 36

lubricant
electrode

Question 37

Describe the giant covalent structure of silicon(IV) oxide.

Answer 37

each Si atom has four electrons in the outer shell, making 4 covalent bonds w/ oxygen to obtain a full outermost shell

Question 38

Describe the similarity in properties between diamond and silicon(IV) oxide. Why is this?

Answer 38

• form transparent crystals
• very hard (made from many strong covalent bonds in a giant structure)
• extremely high melting + boiling points
• do not conduct electricity (no delocalised electrons)
• do not dissolve in water (no charged particles)

Question 39

Why do both diamond and silicon (IV) oxide not conduct electricity?

Answer 39

there are no delocalised electrons which can move

Question 40

Why do both diamond and silicon (IV) oxide not dissolve in water?

Answer 40

no charged particles

Question 41

Why are both diamond and silicon (IV) oxide very hard?

Answer 41

they are made from many strong covalent bonds in a giant structure

Question 42

Which two giant covalent substances are very similar in terms of their properties?

Answer 42

diamond and silicon (IV) oxide