Chemistry

Question 1

How close together are the particles in a solid

Answer 1

Very close

Question 2

How close together are the particles in a liquid

Answer 2

Quite close

Question 3

How close together are the particles in a gas

Answer 3

Wide apart

Question 4

How are the particles arranged in a solid

Answer 4

Ordered

Question 5

How are the particles arranged in a liquid

Answer 5

Random

Question 6

How are the particles arranged in a gas

Answer 6

Random

Question 7

How do the particles move in a solid

Answer 7

Vibrate only

Question 8

How do the particles move in a liquid

Answer 8

Move fairly freely

Question 9

How do the particles move in a gas

Answer 9

Move freely

Question 10

Why do liqiuds and gases take the shape of their container

Answer 10

Particles can move around

Question 11

Why do solids not take the shape of their container

Answer 11

Particles cannot move around

Question 12

Why can gases be squashed easily

Answer 12

There are big spaces between the particles

Question 13

Why can’t solids and liquids be squashed easily

Answer 13

Particles are close together and can’t move

Question 14

What is the change of state from solid to gas called

Answer 14

Sublimation

Question 15

What is the change of state from gas to solid called

Answer 15

Deposition

Question 16

What is the change of state from solid to liquid called

Answer 16

Melting

Question 17

What is the change of state from liquid to gas called

Answer 17

Boiling

Question 18

What is the change of state from gas to liquid called

Answer 18

Condensing

Question 19

What is the change of state from liquid to solid called

Answer 19

Freezing

Question 20

What are the differences and similarities between boiling and evaporation

Answer 20

Same: Change from liquid to gas

Difference:
Boiling: Boiling occurs at a set temperature, Occurs throughout the liquid, there’s bubbles.

Evaporation: can occur below b.p, only happens at the surface, there’s no bubbles

Question 21

When ethanol is heated it boils at 78°C. Its temperature doesn’t rise while it boils. Explain why the temperature
does not rise even though the ethanol is being heated.

Answer 21

The energy is used to change state instead of increasing the temperature. It is needed to overcome forces between particles

Question 22

What is in the nucleus of an atom

Answer 22

Protons and neutrons

Question 23

What is in shells around the nucleus in an atom

Answer 23

Electrons

Question 24

What is the relative mass of a proton

Answer 24

1

Question 25

What is the relative mass of a neutron

Answer 25

1

Question 26

What is the relative mass of an electron

Answer 26

1/2000

Question 27

What is the charge of an proton

Answer 27

+1

Question 28

What is the charge of a neutron

Answer 28

0

Question 29

What is the charge of an electron

Answer 29

-1

Question 30

How to calculate the number of each particle

Answer 30

The atomic numer, protons and electrons are always the same amount. The number of neutrons is the mass number minus the number of protons

Question 31

Why are atoms always neutral

Answer 31

The atoms of an element contain equal numbers of protons and electrons and so have no overall charge.

Question 32

What are the rules of maximum amount of electrons in each shell.

Answer 32

1st: 2 2nd: 8 3rd: 8 4th: the rest

Question 33

What is an isotope?

Answer 33

Different forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nucleus

Question 34

What is formula mass

Answer 34

When 2 elements chemically combine to make a compound, the name of the 2nd elements name changes to - ide. Magnesium + sulphur -> Magnesium Sulphide

Question 35

How do you work out the formula mass

Answer 35

When we work out the formula Mass for a compound, we must add together the atomic masses of all the elements in the formula. You must write the number as a subscript (like an indices but below the number).

Question 36

Work out the formula mass for aluminium Sulphate Al2(SO4)3

Answer 36

``` (2xAl) + [(1xS) + (4xO)]3 (2x27) + [(1x32) + (4x16)]3 (2x27) + (32+64)3 54 + (96) x 3 54 + 288 = 342 ```

Question 37

How many elements are there

Answer 37

118 92 natural 26 man-made

Question 38

What is a mole

Answer 38

A mole is just a number A mole is 6.022 x 10^23 1g is a mole of hydrogen which has a relative formula of 1. For example water has a relative formula mass of 18 and a mole of water is 18g. This means that that 2 moles of water equals 36g.

Question 39

How to work out the number of moles

Answer 39

Number of moles = mass of substance divided by relative formula mass.

Question 40

What is avogadro's number

Answer 40

6.02 x10^23

Question 41

How to work out the number of particles

Answer 41

Number of particles = number of moles x 6.02 x 10^23

Question 42

How to find the percentage of an element in a compound

Answer 42

Percentage of an element in a compound = mass of element in compound divided by relative formula mass of compound x100