Chapter 3

Question 1

There are 3 sub-atomic particles

Answer 1

• protons
• neutrons
• electrons

Question 2

These sub atomic particles are found in the nucleus

Answer 2

• neutrons

- protons

Question 3

State the relative charges and approximate relative masses of protons, neutrons and electrons

Answer 3

Protons: +, 1
Neutrons: 0, 1
Electrons: -, 0

Question 4

Define proton number

Answer 4

The number of protons in the nucleus of an atom

Question 5

Define nucleon number

Answer 5

The total number of protons and neutrons in the nucleus of an atom

Question 6

Define isotopes

Answer 6

Atoms of the same element which have the same proton number but a different nucleon number

Question 7

State the two types of isotopes

Answer 7

Radioactive and non-radioactive

Question 8

Why do isotopes have the same properties?

Answer 8

It is because they have the same number of electrons in their outer shell.

Question 9

State one medical and one industrial use of radioactive isotopes

Answer 9

To kill cancer cells with radiotherapy - Cobalt_60
Generates x-rays for fracture diagnosis - Iridium_192
Diagnosis of anaemia - Iron_59

Power source for space shuttles - Plutonium_238
Detects presence of explosives in airline luggage - Californium_252
Produces alpha radiation for use in smoke detectors - Americium_241

Question 10

Describe the differences between elements, mixtures and compounds, and between metals and non-metals

Answer 10

Elements: An amount of substance that contains only one type of atom, including isotopic variations.

Mixtures: When two or more substances are found together but are not chemically bonded to each other.

Compounds: Made up of 2 or more atoms of different elements that are joined together through chemical bonds.

Metals: Large atomic radii, can conduct heat and electricity, high range of melting points, malleable and ductile, shiny

Non-metals: Small atomic radii, can not conduct heat and electricity, generally low melting point, brittle, dull

Question 11

Describe an alloy

Answer 11

A mixture of a metal with other elements. Created by mixing two melted metals and allowing them to cool down.

Question 12

Describe the formation of ions

Answer 12

Ions are formed through the loss or gain of electrons.

Question 13

Describe the formation of ionic bonds between elements from Groups I and VII

Answer 13

Elements that are metal get rid of their outermost electrons while non-metals try to gain more electrons in their outermost shell. This is to achieve a noble gas configuration to become stable. To do this, an electron is transferred from a metal element to a non-metal element.

Question 14

Cations and anions

Answer 14

Positive ions are cations, negative ions are anions. Most metals are cations and most non-metals are anions.

Question 15

Why don’t metals gain electrons to achieve a noble gas configuration?

Answer 15

This is because it would take much more energy to do so instead of just losing electrons.

Question 16

Describe the formation of ionic bonds between metallic and non-metallic elements

Answer 16

Due to an electron transfer, there is a strong force of attraction between metals and non-metals

Question 17

Describe the lattice structure of ionic compounds

Answer 17

A regular arrangement of alternating positive and negative ions

Question 18

Why are ionic lattices formed?

Answer 18

This is because of the strong electrostatic forces between each atom

Question 19

What is Valency?

Answer 19

The number of electrons either gained or lost during ionisation.

Question 20

Describe the formation of single covalent bonds in H2, Cl2, H2O, CH4, NH3 and HCl

Answer 20

The sharing of pairs of electrons leading to the noble gas configuration

Question 21

Describe the differences in volatility, solubility and electrical conductivity between ionic and covalent compounds

Answer 21

Covalent compounds: High volatility, low solubility and no electrical conductivity.

Ionic compounds: Low volatility, High solubility and only electrical conductivity when molten or in a solution.

Question 22

What is a covalent bond?

Answer 22

A force of attraction between non-metals through the sharing of an electron.

Question 23

Describe the electron arrangement in more complex covalent molecules such as N2, C2H4, CH3OH and CO2

Answer 23

They are more complex as they have double, triple etc bonds.

Question 24

Explain the differences in melting point and boiling point of ionic and covalent compounds in terms of attractive forces

Answer 24

The melting point and boiling point of ionic compounds are higher because they have a much stronger attraction and intermolecular forces in their ionic lattices and therefore require much more energy in order to be separated.

Question 25

Describe the giant covalent structures of graphite and diamond

Answer 25

Graphite has carbon molecules connected through 3 covalent bonds. They form layers instead of the structure diamonds have. Diamonds are connected to 4 different other carbon molecules and are pyramid built

Question 26

What are the properties of macromolecules?

Answer 26

There is a centre molecule that has a noble gas configuration but not the ones its connected to. The consistent repetition of this pattern generates a huge molecule that is extremely hard, insoluble and has very high melting and boiling points.

Question 27

Relate macromolecules from their structures to their uses

Answer 27

Graphite has soft, slippery layers with delocalised electrons in between that make it useful as a lubricant and conductor while diamond due to its “infinite” structure is very hard and strong. Making it useful for cutting through things.

Question 28

Describe the macromolecular structure of silicon(IV) oxide (silicon dioxide)

Answer 28

like pyramid structures, similar to that of a diamond

Question 29

Describe the similarity in properties between diamond and silicon(IV) oxide, related to their structures

Answer 29

Like diamond, silicon dioxide forms transparent crystals, is very hard and has extremely high melting and boiling points. It is also insoluble and does not conduct electricity. Similar to that of a diamond.

Question 30

A metal bond

Answer 30

A force of attraction between the positive metal ions and their delocalised electrons.

Question 31

Describe metallic bonding

Answer 31

A lattice of positive ions in a ‘sea of electrons.’ The delocalised electrons can carry electrical currents and since it is therefore difficult to break their bonds, make them malleable and conductible.