Chemistry

Question 1

Around how many different types of elements are there in the periodic table?

Answer 1

100

Question 2

What does it mean if a compound ends in–ide?

Answer 2

Contains 2 elements; usually metal and non-metal.

Question 3

What does it mean if a compound ends in –ate?

Answer 3

Contains 3 or more elements, 1 of which is always oxygen.

Question 4

What does a chemical reaction involve?

Answer 4

The formation of one or more new substances; usually with an energy change.

Question 5

Name the following substances:
NaCl
NaSO4

Answer 5

NaCl Sodium chloride.

NaSO4 Sodium sulfate.

Question 6

Why is it useful to have symbols for atoms of different elements?

Answer 6

When elements join together to form a compound, it tells you how many atoms there are.

Question 7

What is the difference between an element and a compound?

Answer 7

Elements contain one type of atom and compounds contain more than one type.

Question 8

Why is it difficult to separate a compound?

Answer 8

A compounds elements are chemically joined together.

Question 9

What is the difference between a compound and a mixture?

Answer 9

The substances in a mixture are not chemically bonded together, but they are in a compound.

Question 10

Describe the method used to collect the salt from a mixture of sand and salt.

Answer 10

Add water and stir to dissolve the salt. Use filtration to remove the sand. Heat the water (gently) to allow the salt to crystallize (to avoid dryness).

Question 11

What process is used to purify seawater to obtain usable water?

Answer 11

Simple distillation.

Question 12

Describe how the following equipment is used to separate water and ethanol.

Answer 12

The ethanol and water mixture are heated. Ethanol has a boiling point of 78°C and will vaporize first. The gas passes over the fractional column and into the condenser. Here it will condense, turning back into it’s liquid state.

Question 13

What was the earliest model of the atom?

Answer 13

Tiny spheres that could not be divided.

Question 14

Which early atomic model does the following diagram show?

Answer 14

The plum pudding model.

Question 15

Name Rutherford’s experiment.

Answer 15

Alpha particle scattering.

Question 16

State two ways in which Rutherford’s experiment changed Thomson’s model of the atom.

Answer 16

He said the positive charge was concentrated into very small volume at center of atom (nucleus) and the electrons orbit nucleus.

Question 17

Explain why Bohr revised Rutherford’s model of the atom.

Answer 17

Suggesting electrons orbit the nucleus at different distances.

Question 18

Explain why Bohr revised Rutherford’s model of the atom.

Answer 18

Energy emitted from electron transitions can only have certain fixed energies, so he refined the ‘orbiting electrons’ in Rutherford’s nuclear model to ‘orbiting electrons in energy levels (or shells) at fixed distances from the nucleus’.

Question 19

Name three subatomic particles and their charges.

Answer 19

Proton – positive; neutron – no charge; electron – negative.

Question 20

Complete the sentence ‘All atoms of one type of element have the same number of…’

Answer 20

Protons.

Question 21

What does the atomic number tell us about an atom?

Answer 21

Number of protons.

Question 22

What does the mass number tell us about an atom?

Answer 22

Number of protons + number of neutrons.

Question 23

How is an isotope different to an atom?

Answer 23

Different number of neutrons.

Question 24

What is the electron configuration for sodium?

Answer 24

2,8,1

Question 25

Why is the overall charge of an atom zero?

Answer 25

Number of protons (positive) = number electrons (negative).

Question 26

How many electrons does potassium have on its highest energy level?

Answer 26

1

Question 27

Calculate how many protons, electrons and neutrons there are in: a) A silver atom with atomic number 47 and mass number 108

Answer 27

a) A silver atom with atomic number 47 and mass number 108 Protons = 47 Electrons = 47 Neutrons = 61

Question 28

How are elements arranged in the modern periodic table?

Answer 28

Increasing atomic number.

Question 29

What are the columns of the periodic table called?

Answer 29

Groups.

Question 30

What are the rows of a periodic table called?

Answer 30

Periods.

Question 31

What does the column an element is in tell you about the atoms?

Answer 31

Number of electrons in outer shell.

Question 32

What does the row an element is in tell you about the atoms?

Answer 32

Number of electron shells.

Question 33

Which side of the periodic table are the non-metals found?

Answer 33

Right and top.

Question 34

How were elements classified before the discovery of subatomic particles?

Answer 34

Arranging in order of their atomic weights.

Question 35

What was the problem with early periodic tables?

Answer 35

Incomplete; some elements placed in inappropriate groups.

Question 36

How did Mendeleev overcome these problems?

Answer 36

Left gaps for elements he thought had not yet been discovered; changed the order based on atomic weights for some elements if they did not fit the pattern.

Question 37

Why is the order based on atomic masses not always correct?

Answer 37

The presence of isotopes.

Question 38

What do we call elements that tend to form positive ions?

Answer 38

Metals.

Question 39

What are the elements in Group 0 called?

Answer 39

Noble gases.

Question 40

What are the elements in Group 1 called?

Answer 40

Alkali metals.

Question 41

What are the elements in Group 7 called?

Answer 41

Halogens.

Question 42

What happens to the boiling point of elements in Group 0 as you go down the group?

Answer 42

Increase.

Question 43

Why are the elements in Group 0 so unreactive?

Answer 43

Full outer shell of electrons.

Question 44

Why do all elements in Group 1 react in a similar way to each other?

Answer 44

1 electron in outer shell.

Question 45

What happens to the reactivity of the elements as you go down Group 1?

Answer 45

Increases.

Question 46

Write a word equation for the reaction between sodium and oxygen.

Answer 46

sodium + oxygen - sodium oxide

Question 47

Why do all the elements in Group 7 react in a similar way to each other?

Answer 47

7 electrons in outer shell.

Question 48

Halogens are diatomic. What does the word ‘diatomic’ mean?

Answer 48

There molecules contain 2 atoms.

Question 49

What happens to the reactivity as you go down Group 7?

Answer 49

Decreases.

Question 50

What happens to the melting point and boiling point as you go down Group 7?

Answer 50

Increases.

Question 51

Write a word equation for the reaction between lithium and chlorine.

Answer 51

lithium + chlorine - lithium chloride

Question 52

Where are transition metals found on the periodic table?

Answer 52

Between Group 2 and Group 3.

Question 53

How do the melting points of transition metals compare to Group 1 metals?

Answer 53

Transition metals have a higher melting point than alkali metals.

Question 54

How do the densities of transition metals compare to Group 1 metals?

Answer 54

Transition metals are more dense than alkali metals.

Question 55

How does the strength of transition metals compare to Group 1 metals?

Answer 55

Transition metals are stronger than alkali metals.

Question 56

Describe the differences between the reactions of the alkali metals and the reactions of transition metals.

Answer 56

Alkali metals react vigorously with water and with oxygen from the air. The transition elements react slowly with these reagents if at all.

Question 57

State two typical properties of transition metals.

Answer 57

Have ions with different charges; form coloured compounds.

Question 58

State one use of transition metals.

Answer 58

Transition metals can be used as catalysts.

Question 59

Explain why copper is used for plumbing.

Answer 59

It has a high melting point, it conducts heat and is strong and malleable. It also does not react with water.

Question 60

Why is it incorrect to say iron is heavier than wood?

Answer 60

It depends how much iron and wood you have. You should say iron is denser than wood.

Question 61

Water has a density of 1000 kg/m3. A piece of rubber has a density of 1024 kg/m3. Explain what would happen if the rubber was put in a pool of water?

Answer 61

Rubber has a higher density than water so the rubber would sink in water.

Question 62

A sheet of insulating foam measures 3 m x 1 m x 0.08 m. It has a mass of 9.6 kg. Calculate the density of the insulating foam.

Answer 62

V = 3 x 1 x 0.08 = 0.24 m3 Density = 9.6 / 0.24 = 40 kg/m3

Question 63

High density foam is made of the same material and can be used to give better insulation for the same thickness of foam. Describe how the arrangement of particles would differ in these two types of foam (you may draw diagrams to help your answer).

Answer 63

Particles in the high density foam will be closer together so there are more particles in a given volume, making it denser.

Question 64

When copper metal is heated to 1100 oC it melts.   a. Is this a chemical or physical change? Explain your answer. b. What will happen to the mass of the sample of copper after it has melted? Explain your answer.

Answer 64

a. Is this a chemical or physical change? Explain your answer. Physical change. No new products have been formed. b. What will happen to the mass of the sample of copper after it has melted? Explain your answer. It will stay the same. Mass is conserved when state changes.

Question 65

Explain the difference between a physical and a chemical change.

Answer 65

In a physical change no new products are formed and it can be easily reversed. In a chemical change a new substance is formed which can not easily be changed back .

Question 66

Name the 6 states of matter.

Answer 66

1. melting 2. evaporating 3. deposition 4. subliming 5. condensing 6. freezing

Question 67

If you wanted to find the density of a brass key, you first need to measure its volume. Describe how to determine the volume of a brass key.

Answer 67

Drop the key into a known volume of water and measure the amount of water displaced by the key. This will be the volume of the key.

Question 68

Define internal energy?

Answer 68

The total kinetic and potential energy of all the particles within a system.

Question 69

Which of the following will change the internal energy of a stone? A. Lifting it to the top of a building B. Heating it C. Firing it from a catapult

Answer 69

Heating it.

Question 70

Water and the chemical isooctane both boil at 100 degrees. When the same amount of each substance is placed on a heater, the isooctane boils first. Explain why this happens.

Answer 70

Isooctane has a lower specific heat capacity than water so less heat energy is needed to raise its temperature to its boiling point.

Question 71

What is latent heat?

Answer 71

The energy needed to change the state of a substance without changing the temperature.

Question 72

Explain the difference between latent heat of fusion and latent heat of vaporisation.

Answer 72

Latent heat of fusion is the energy needed to change between solid and liquid. Latent heat of vaporisation is the energy needed to change state between liquid and gas.

Question 73

In which state are the particles randomly arranged?

Answer 73

Liquid and Gas

Question 74

In which state are the particles only able to vibrate in a fixed position?

Answer 74

Solid.

Question 75

Which state can be compressed or squashed easily?

Answer 75

Gas.

Question 76

Which state cannot flow from place to place?

Answer 76

Solid.

Question 77

Particles in which state have no bonds?

Answer 77

Gas.

Question 78

Particles in which state sit in a regular pattern and are held together tightly by bonds.

Answer 78

Solid.

Question 79

At room temperature, what state is mercury in?

Answer 79

Liquid.

Question 80

What happens to the pressure of a gas when it is heated at constant volume?

Answer 80

Increases.

Question 81

When 100 grams of water is boiled, what mass of steam is made?

Answer 81

100 grams of steam would be produced because of the conservation of mass.

Question 82

What is density?

Answer 82

Mass per Unit Volume.

Question 83

How do we calculate density?

Answer 83

Mass divided by Volume.

Question 84

What are the units of density?

Answer 84

Kg/m3.

Question 85

What do we use to measure the volume of oddly shaped object?

Answer 85

The eureka can.

Question 86

What does not normally change much when substances melt?

Answer 86

Volume per Units Mass.

Question 87

How do we calculate volume?

Answer 87

Length times width times height.

Question 88

How will we know if a substance is less dense than water?

Answer 88

It will float on water.

Question 89

What is the density of water?

Answer 89

1000 Kg/m3.

Question 90

After which scientist is the eureka can named?

Answer 90

Archimedes.

Question 91

What happens to the least dense of two immicible liquids?

Answer 91

It rises to the top.

Question 92

An object at rest on top of a shelf is likely to have?

Answer 92

Gravitational potential energy.

Question 93

Batteries are stores of?

Answer 93

Chemical energy.

Question 94

Energy is usefully transferred from personal audio player as..?

Answer 94

Sound energy.

Question 95

Which is likely to have the most thermal energy? | A red hot horse shoe or A spark from a firework?

Answer 95

A red hot horse shoe.

Question 96

Which is likely to have the highest temperature? | A red hot horse shoe or A spark from a firework?

Answer 96

A spark from a firework.

Question 97

Which type of energy transfer requires particles?

Answer 97

Conduction.

Question 98

Thermal energy is transferred by conduction from?

Answer 98

The hot end to the cold end.

Question 99

Which type of energy transfer can occur through a vacuum?

Answer 99

Radiation.

Question 100

What type of energy is stored in a wind up toy?

Answer 100

Gravitational potential energy.

Question 101

What type of diagram shows the efficiency of energy transfer?

Answer 101

Sankey Diagrams.

Question 102

What is specific latent heat?

Answer 102

The energy needed to change the state of a substance without changing its temperature.

Question 103

What is latent heat of fusion?

Answer 103

The amount of energy required to change the state of 1 kg of a solid to a liquid. The amount of energy released when 1 Kg of a substance changes from liquid to solid.

Question 104

What is specific latent heat of vaporization?

Answer 104

The amount of energy required to change the state of 1 Kg of a liquid to a gas. The amount of energy released when 1 kg of a substance changes from gas to liquid.

Question 105

What is the name of the variable that tells you how much heat energy is required to change the state of 1 kg of a substances?

Answer 105

Specific latent heat.

Question 106

What happens to the temperature of an object when it changes from a solid to a liquid?

Answer 106

It remains the same.

Question 107

What happens to the temperature of an object when it changes from a liquid to a gas?

Answer 107

It remains the same.

Question 108

Why does the temperature of ice remain at 0*C when it is melting?

Answer 108

Heat energy altering the chemical bonds altering between the particles.

Question 109

What is a burn from at 100*C more harmful than a burn from water at 100*C?

Answer 109

More energy being released when steam condenses to water.

Question 110

If someone gets wet in cold weather, why will they feel colder?

Answer 110

The water will evaporate from their skin and take heat from their body to do so.

Question 111

Why do tumble dryers require a lot of electrical energy to operate?

Answer 111

Water has high specific latent heat value and a lot of energy is required to evaporate the water.