P1 - Atomic Structure and the Periodic Table

Question 1

What is an element?

Answer 1

A substance containing only one type of atom

Question 2

What is a compound?

Answer 2

A substance containing 2 or more different types of atoms chemically bonded

Question 3

What is a mixture?

Answer 3

A substance containing 2 or more different types of atoms not chemically bonded

Question 4

Does filtration separate an insoluble or soluble solid from a liquid?

Answer 4

Insoluble

Question 5

What equipment do we use for filtration?

Answer 5

• Filter funnel
• Filter paper
• Conical flask

Question 6

Does crystallisation separate an insoluble or soluble solid from a liquid?

Answer 6

Soluble

Question 7

When sodium chloride is dissolved in water, what is the solute and the solvent?

Answer 7

The solute is the dissolved sodium chloride
The solvent is the water

Question 8

What equipment do we use for evaporation?

Answer 8

• Evaporating dish (crucible)
• Tripod
• Bunsen burner

Question 9

What are the 2 benefits of the separating method ‘evaporation’?

Answer 9

• Quick
• Easy

Question 10

What is 1 issue of the separating method ‘evaporation’?

Answer 10

Some solids will decompose from the heat (thermal decomposition)

Question 11

TRUE OR FALSE: We use crystallisation for solids that are susceptible to thermal decomposition

Answer 11

True

Question 12

Is the separating technique ‘evaporation’ quicker or slower than ‘crystallisation’?

Answer 12

Quicker

Question 13

How can we heat our solution more gently in crystallisation?

Answer 13

With a water bath
(instead of a bunsen burner like in evaporation)

Question 14

Do we continue heating the solution when we see start to see crystals forming once some solvent has evaporated in crystallisation?

Answer 14

No

Question 15

In crystallisation, after heating the solution we leave it to cool and see more crystals. Why is this?

Answer 15

As the solution cools, more crystals will start to form because solids are less soluble at colder temperatures.

Question 16

How do we dry crystals in crystallisation?

Answer 16

Warming them in an oven.

Question 17

What’s an aqueous solution?

Answer 17

A solution in water

Question 18

When do we use simple distillation?

Answer 18

When we want to separate a dissolved solid from a liquid but want to keep the liquid

Question 19

In short, how do we carry out simple distillation?

Answer 19

• Evaporate the liquid by heating which turns it into vapour
• We condense the vapour back to a liquid by cooling

Question 20

How do we carry out simple distillation? Full answer
Hints:
1- Vapour
2- Glass tube, thermometer
3- Boiling, vapour, condenser
4- Condenser, condense
5- Beaker, flask

Answer 20

The heated solution turns into vapour.
As it rises up the glass tube the thermometer reading increases.
We continue heating until the solution is boiling and then the vapour is in the condenser.
The condenser contains circulating cold tap water which causes the vapour to condense into a liquid.
We collect the liquid in a beaker and we’re left with crystals of the solid in the flask

Question 21

In simple distillation, does the condenser heat or cool the vapour?

Answer 21

Cools

Question 22

TRUE OR FALSE: We can use simple distillation to produce drinking water

Answer 22

TRUE: However it’s not recommended since lots of energy is used up
Extra: We have other, more efficient techniques for this

Question 23

When do we use fractional distillation?

Answer 23

When we want to separate several liquids with different boiling points

Question 24

What are the hundreds of glass beads in fractional distillation called?

Answer 24

Fractionating column

Question 25

How do we carry out fractional distillation? Hints: 1- Heat, evaporate 2- Condense, fractionating column, flask 3- Lower boiling point chemical, fractionating column 4- Thermometer, mixture, lower boiling point 5- Condenser, liquid, mixture 6- Thermometer, stops, condensed, fresh beaker 7- Thermometer 8- Thermometer, stops, condensed, fresh beaker 9- Separation

Answer 25

We heat the mixture and both liquids will begin to evaporate. The 2 vapours condense in the fractionating column and drip back into the flask. This repeated process increases the amount of the lower boiling point chemical in the factionating column. The themometer reading rises as the vapours reach it but the mixture contains more of the lower boiling point. They pass through the condenser and turn into a liquid but are still a mixture The thermometer reading stops rising and that's when the lower boiling point chemical gets condensed and drips into a fresh beaker The reading rises again The reading stops rising again and the higher boiling point chemical gets condensed and drips into another fresh beaker Now they're separated!

Question 26

During fractional distillation, what are the 2 factors that mean we either can't separate the liquids or struggle to?

Answer 26

- Similar boiling points: We may need to carry out multiple rounds - Large volume (e.g. crude oil) : The equipment we use isn't suitable

Question 27

What do all separation techniques have in common?

Answer 27

Being a physical process Extra: This means they don't involve chemical reactions No new substances are made

Question 28

What does paper chromotography allow us to do?

Answer 28

To separate substances based on their different solubilites

Question 29

How do we carry out the chromotography paper experiment? Hints: 1- Chromotography paper 2- Pencil 3- 2 colours 4- Paper, solvent 5- Solvent, ink, 2 colours 6- Ink

Answer 29

1- Take chromotography paper 2- Draw a pencil line near the bottom 3- Put a dot of the first colour on the pencil line and next to it, place another dot of a second colour 4- Place the bottom of the paper into a solvent 5- Solvent moves up the paper and dissolves the ink in the 2 coloured dots 6- The ink is carried up

Question 30

What do we call the paper in paper chromotography?

Answer 30

Stationary phase Extra: Because it doesn't move

Question 31

What do we call the solvent in paper chromotography?

Answer 31

Mobile phase Extra: Because it moves

Question 32

How do you know a colour is a pure colour in paper chromotography?

Answer 32

There's only 1 spot of the single colour

Question 33

How do you know a colour is a mixture of colours in paper chromotography?

Answer 33

The single colour has separated into more than 1 different spots

Question 34

TRUE OR FALSE: In paper chromotography, a pure compound will produce 2 spots of a single colour in all solvents

Answer 34

FALSE: A pure compound will produce a single spot in all solvents

Question 35

In paper chromotography, will the compounds in a mixture separate into different spots depending on the solvent?

Answer 35

Yes

Question 36

Why does paper chromotography work?

Answer 36

Because different substances have different solubilities

Question 37

TRUE OR FALSE: In paper chromotography, a more soluble substance is more attracted to the mobile phase (solvent) than a less soluble substance

Answer 37

TRUE

Question 38

In paper chromotography, does a less soluble substance travel further than a substance which is more soluble?

Answer 38

No A MORE soluble substance travels further than a LESS soluble substance

Question 39

Common exam question for paper chromotography: WHY DO WE DRAW OUR STARTING LINE IN PENCIL?

Answer 39

Because if we drew the line in pen, the pen ink could dissolve in the solvent and move up the paper

Question 40

What's a solvent?

Answer 40

A liquid that will dissolve substances

Question 41

For paper chromotography, how many colours can we use?

Answer 41

Several colours Extra: As long as there's enough space

Question 42

Why was the alpha scattering experiment used?

Answer 42

To find out if the Plum Pudding Model was correct

Question 43

What happened in the alpha scattering experiment + how was it carried out? Hints: 1- Gold foil 2- Particles 3- Through 4- Deflected 5- Bounced

Answer 43

- Piece of gold foil because it's easy to hammer down gold into a few atoms thick - Tiny alpha particles were fired at the gold foil - Most alpha particles went straight through - Some alpha particles were deflected - Some alpha particles bounced straight back

Question 44

In the alpha scattering experiment, what did scientists find out because most alpha particles went straight through the gold foil?

Answer 44

That atoms are mainly empty space Extra: They immediately knew the plum pudding model was wrong

Question 45

In the alpha scattering experiment, what did scientists find out because some alpha particles were deflected?

Answer 45

The centre of the atom has a positive charge

Question 46

In the alpha scattering experiment, what did scientists find out because some alpha particles bounced straight back?

Answer 46

The centre of the atom contains lots of mass

Question 47

What model was the Plum Pudding Model replaced with?

Answer 47

The Nuclear Model

Question 48

What charge do alpha particles have?

Answer 48

Positive

Question 49

Why would alpha particles get deflected when going near the positive centre of an atom?

Answer 49

Alpha particles are positive so they would be repelled and change direction

Question 50

In the nuclear model, how much of the atom is empty space?

Answer 50

In the nuclear model, most of the atom is empty space

Question 51

What scientist proposed the idea that electrons orbit the nucleus in an atom?

Answer 51

Niels Bohr proposed the idea

Question 52

What do we call the orbits in an atom?

Answer 52

- Energy levels OR - Shells

Question 53

Why does the nucleus have a positive charge?

Answer 53

The nucleus has a positive charge because of protons

Question 54

What determines the amount of positive charge in the nucleus?

Answer 54

Number of protons determines it

Question 55

What scientist discovered that the nucleus contains neutrons

Answer 55

James Chadwick discovered it

Question 56

What's the radius of an atom?

Answer 56

0.1 nanometres (1x10^-10 m)

Question 57

What's the radius of the nucleus?

Answer 57

1x10^-14 m

Question 58

TRUE OR FALSE: Half of an atom's mass is found in the nucleus

Answer 58

FALSE: Nearly all of the mass of an atom is found in the nucleus

Question 59

TRUE OR FALSE: Atoms have no overall charge

Answer 59

TRUE

Question 60

What's the relative charge and relative mass of: Protons, neutrons, electrons

Answer 60

Proton = +1, 1 Neutron = 0, 1 Electron = -1, very small

Question 61

What are isotopes?

Answer 61

Isotopes are atoms of the same element with different numbers of neutrons

Question 62

What are ions?

Answer 62

Ions are atoms which have an overall charge Extra: Because they have lost or gained electrons

Question 63

What does the number of electrons in the outer energy level tell us?

Answer 63

The group number of that element on the periodic table

Question 64

What is group 0 on the periodic table called?

Answer 64

Noble gases

Question 65

Are the metal elements in group 1 highly unreactive or reactive?

Answer 65

Reactive

Question 66

Are the non-metals in group 7 highly unreactive or reactive?

Answer 66

Reactive

Question 67

Why do elements in the same group have similar chemical properties?

Answer 67

They have the same number of electrons in their outer energy level

Question 68

Who called elements that came in threes "triads"?

Answer 68

Johann Dobereiner

Question 69

What do lithium, sodium and potassium all react rapidly with?

Answer 69

Water

Question 70

Who ordered the elements in order of increasing atomic weight?

Answer 70

John Newlands

Question 71

Who created "law of octaves" (every 8th element reacting in a similar way)?

Answer 71

John Newlands

Question 72

What was a problem with John Newlands' law of octaves?

Answer 72

Some elements with very different properties were grouped together

Question 73

Who developed the 1st modern periodic table?

Answer 73

Dmitri Mendeleev

Question 74

How did Dmitri Mendeleev creat the periodic table?

Answer 74

Firstly, he arranged all elements in increasing atomic weight However, he would swap specific elements so they fitted other elements in the same group Secondly, he left space for undiscovered elements

Question 75

What did Mendeleev predict correctly?

Answer 75

The undiscovered elements for where he left the gaps in the periodic table

Question 76

What's 1 difference between Mendeleev's periodic table and the modern periodic table?

Answer 76

They are now arranged in order of atomic number (number of protons)

Question 77

Why is ordering elements by atomic weight wrong?

Answer 77

Some will appear in the wrong order due to isotopes

Question 78

What group on the periodic table was not fully discovered at Mendeleev's time?

Answer 78

Group 0

Question 79

Are the noble gases very unreactive or very reactive elements?

Answer 79

Very unreactive

Question 80

Why are some elements unreactive?

Answer 80

- Full outer energy level

Question 81

When are atoms stable?

Answer 81

When they have a full outer energy level

Question 82

Do the noble gases have boiling points of above or below room temperature?

Answer 82

Below

Question 83

Do the boiling points of the noble gases increase or decrease as the relative atomic mass increases (moving down group 0)

Answer 83

Increase

Question 84

Where do we find metals on the periodic table?

Answer 84

On the left and the centre

Question 85

Where do we find non-metals on the periodic table?

Answer 85

On the right side

Question 86

When metals react, do they lose or gain electrons?

Answer 86

Lose electrons to achieve a full outer energy level

Question 87

When metals achieve a full outer energy level, what electronic structure does it give them?

Answer 87

The electronic structure of a group 0 noble gas

Question 88

TRUE OR FALSE: Metals always form negative ions

Answer 88

FALSE: Metals always form positive ions

Question 89

What group is the alkaline metals?

Answer 89

Group 1

Question 90

How many electrons do group 1 metals have in their outer energy level?

Answer 90

1 electron

Question 91

Are group 1 metals hard or soft?

Answer 91

Soft

Question 92

TRUE OR FALSE: Group 1 metals react rapidly with oxygen

Answer 92

TRUE

Question 93

As we move down group 1, do the metals react more or less rapidly?

Answer 93

More rapidly