Chapter 2

Question 1

What is the atomic number?

Answer 1

The number of protons

Question 2

Atoms of different elements will have different number of….

Answer 2

Protons

Question 3

What is an isotope?

Answer 3

When there is the same number of protons but different number of neutrons (same atomic number but different mass numbers)

Question 4

What is ionic bonding?

Answer 4

Atoms loose or gain electrons to form charged particles (ions) which are strongly attracted to each other because of their opposite charges)

Question 5

How is the structure of an ionic compound described as?

Answer 5

A regular lattice structure

Question 6

Name some of the properties of ionic compounds

Answer 6

• high melting points
• high boiling points
• can carry electric current when melted
• dissolve easily

Question 7

Explain the properties of ionic compounds

Answer 7

• High melting and boiling points because of the strong forces of attraction between the ions therefore it takes a large amount of energy to overcome this attraction
• they can carry electric current because when it melts the ions separate and are free to move in the solution so they will carry electric current

Question 8

When metal atoms become ions what charge do they have?

Answer 8

Positive charges ( they loose electrons)

Question 9

When non metals become ions what charge do they have?

Answer 9

Negative (they gain electrons)

Question 10

Work out the formula of this ionic compound:

Mg2+ Cl-

Answer 10

MgCl2

Question 11

What is covalent bonding?

Answer 11

When atoms share electrons with other atoms to obtain full outer shells

Question 12

Give some properties of simple molecular substances

Answer 12

• usually gasses or liquids, sometimes solids
• don’t conduct electricity
• low melting + boiling points (intermolecular forces are easily broken)

Question 13

Give some properties of giant covalent structures

Answer 13

• there are no charged particles
• all the atoms are bonded to each other (strong covalent bonds)
• don’t conduct electricity
• e.g diamond & and graphite

Question 14

Describe the structure of diamond

Answer 14

• each carbon atoms forms 4 covalent bonds
• hardest natural substance
• Sparkly

Question 15

Describe the structure of graphite

Answer 15

• each carbon atom has 3 covalent bonds this creates layers that are free to slide over each other
• graphite is soft and slippery
• weak intermolecular forces between layers

Question 16

Describe the properties of metals

Answer 16

• free elections that allows the metal to conduct heat and electricity
• strong electrostatic forces of attraction
• layers are able to slide over each other (allows the metal to be bent and shaped)

Question 17

What are alloys?

Answer 17

When two or more metals are mixed up together

Question 18

Why are alloys useful?

Answer 18

Different elements have different sized atoms so when another metal is mixed with a pure metal, the new metal atoms will distort the layers of metal atoms, making it more difficult for them to slide over each other therefore alloys are harder

Question 19

What is the mass number?

Answer 19

The number of protons and neutrons in the atom

Question 20

What are nanoparticles?

Answer 20

Really tiny particles

1nm= 0.000000001m

Question 21

What are fullerenes?

Answer 21

Molecules of carbon shaped like hollow balls or closed tubes
Different fullerenes have different number of carbon atoms

Question 22

Name some uses or nanoparticles

Answer 22

• Large surface area-> new industrial catalysts
• sensors to detect a particular type of molecule
• nanotubes to make stronger, lighter building materials
• new cosmetics
• deliver jobs where they are needed because fullerenes are absorbed more easily by the body

Question 23

Describe thermosoftening polymers

Answer 23

• don’t have cross-linking between chains

- forces between chains are easy to overcome (easy to melt)

Question 24

Describe thermosetting polymers

Answer 24

• have crosslinks (holds chains together in a solid structure
• doesn’t soften when heated
• strong, hard and rigid

Question 25

Describe low density (LD) polythene

Answer 25

Made by heating ethene to about 200°C under high pressure Flexible Used for bags and bottles

Question 26

Describe high density (HD) polyethylene

Answer 26

Made at a lower temperature with a catalyst More rigid Used for water tanks and drainpipes

Question 27

What is the relative atomic mass (Ar)

Answer 27

It is the same as the mass number

Question 28

How do you calculate the relative formula mass?

Answer 28

Add up the relative atomic mass

Question 29

What is the relative formula mass of MgCl2

Answer 29

``` Mg= 24 Cl= 35.5 ``` 24 + (35.5 x 2)=95

Question 30

What is one mole of a substance equal to?

Answer 30

It's relative formula mass in grams

Question 31

What is the formula to calculate the number of moles in a substance?

Answer 31

Mass (g) Number of moles= _________________________ Relative formula mass

Question 32

What is the formula for finding the percentage (%) mass of an element or compound?

Answer 32

Relative atomic mass x number of atoms Percentage mass = _____________________________________________ Relative formula mass (of whole compound)

Question 33

Name the steps to calculate masses in reactions

Answer 33

1) write out the balanced equations 2) work out restive formula masses 3) divide to get 1 4) multiply to get all

Question 34

What is percentage yield?

Answer 34

Actual yield vs predicted yield

Question 35

What is the formula for percentage yield

Answer 35

Actual yield ________________ x 100 Predicted yield

Question 36

What is a reversible reaction?

Answer 36

Where the products of the reaction can react to produce the original reactants

Question 37

Describe chromatography

Answer 37

1) a gas is used to carry a substance through a column 2) the substances travel through a column at different speeds 3) the time taken to reach the detector is the retention time 4) the recorder draws a gas chromatograph the number of peaks is the number of compounds in the sample