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GCSE Chemistry > Section 1: Principles of Chemistry > Flashcards

Section 1: Principles of Chemistry Flashcards

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1
Q

What is the arrangement, movement and energy of the particles in a solid?

A

regular, fixed position, no movement, no energy

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2
Q

What is the arrangement, movement and energy of the particles in a liquid?

A

irregular formation, moving, can flow, some energy

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3
Q

What is the arrangement, movement and energy of particles in a gas?

A

far apart, move freely and randomly, high energy

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4
Q

What is the interconversion between solid and liquid and how is it achieved?

A

(TO LIQUID) melting, add heat

(TO SOLID) freezing, remove heat

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5
Q

What is the interconversion between liquid and gas and how is it achieved?

A

(TO GAS) evaporating, add heat

(TO LIQUID) condensing, remove heat

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6
Q

How does changing state work in terms of arrangement, movement and energy of particles?

A

When adding heat, the particles vibrate faster because they have gained energy. They break the arrangement, and move more freely.

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7
Q

What is an atom?

A

smallest particle of an element

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8
Q

What is a molecule?

A

when two or more non-metals are covalently bonded

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9
Q

Describe an experiment to investigate the size and movement of particles (diffusion)

A

Hydrochloric acid is placed at one end of a tube, ammonia solution at the other. Where they meet a ring of ammonium chloride appears. It is closer to the HCL end.
From this we can tell that ammonia must have travelled faster, as it got further in the time. Lighter particles travel faster - so we can tell that ammonia is a lighter gas.

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10
Q

Describe an experiment to investigate the size and movement of particles (dilution)

A

Put a coloured substance in a solvent e.g food colouring in water. You can see that over time the colour levels out but is weaker than the original colour - this is dilution.
Dilution at different temperatures: more heat; means more energy; means more movement; so the particles can move to different areas more quickly. So applying heat decreases the amount of time taken for the coloured substance to be fully diluted.

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11
Q

What is an element?

A

A type of atom

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12
Q

What is a compound?

A

When two or more elements are chemically bonded

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13
Q

What is a mixture?

A

A group of elements which are NOT chemically bonded e.g. air

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14
Q

What is filtration?

A

This consists of a barrier which one component f a mixture can pass through but the other is caught by.
e.g water goes through filter paper, rocks are caught by it

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15
Q

What is distillation?

A

One substance is evaporated off.
e.g salt water is heated to 100 degrees; water evaporates off (it rises and the goes down into the condenser where it is cooled back into water), the salt is left in the original flask.

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16
Q

What is fractional distillation?

A

The mixture is evaporated and rises up the tube.
Different substances have different boiling points and so will condense at different temperatures; as the mixture travels up the tube the temperature decreases, substances begin to condense at different places (due to the change in temperature) and are collected. This separates the mixture into its different parts.

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17
Q

What is crystallisation?

A

A solution is warmed allowing the solvent to evaporate, the solution is now left to cool and will form crystals.

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18
Q

What is chromatography?

A

Chromatography paper is placed in a substance, the different components of the substance will travel at different speeds (due to the size of their particles.)

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19
Q

What is the structure of an atom?

A

Central nucleus composed of protons and neutrons, surrounded by electrons which orbit in electron shells

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20
Q

What is the relative mass and charge of a proton?

A

1, +1

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21
Q

What is the relative mass and charge of a neutron?

A

1, no charge

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22
Q

What is the relative mass and charge of an electron?

A

negligible, -1

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23
Q

What is the atomic number?

A

The number of protons

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24
Q

What is the mass number?

A

The number of protons and neutrons

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25
Q

What is an isotope?

A

An element that has a different number of neutrons, but the same number of protons as another e.g. C12 and C14

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26
Q

What is the relative atomic mass?

A

The weighted average mass of the isotopes of an element

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27
Q

How do you calculate the relative atomic mass of an element from the relative abundances of its isotopes?

A

average weighted mass of one atom of the element/100

Add the products of the percentage abundance and the mass number to get the average weighted mass of one atom.

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28
Q

What is the Periodic table?

A

An arrangement of elements in order of atomic number

29
Q

How do you deduce the electronic configurations of the first 20 elements?

A

Groups show number of electrons on outer shell
Periods show number of shells
Count how many electrons (same as protons)

30
Q

How do you calculate the relative formula mass from relative atomic masses of elements?

A

Add all the relative atomic masses of the individual elements together.

31
Q

What is a mole?

A

An amount of substance

32
Q

What is the relationship between a mole and the Avogadro number?

A

The mole is 6.02 . 10^23 (Avogadro’s number) particles in a substance.

33
Q

What is the relationship between mols, Mr and mass?

A

Mass = Mr.mols

34
Q

What is the relationship between the constant, volume and number of moles? This is used in gases.

A

For dm^3: number of mols = volume/24

For cm^3: number of mols = volume/24,000

35
Q

What do the state symbols show?

A

s - solid
l - liquid
g - gas
aq - aqueous (solution)

36
Q

How do you find the formulae of simple compounds experimentally?

A

Given a compound XY, you need a reaction that separates that compound. For example, if Y was water, you could use simple distillation and record the amount of water lost. At that point, you can deduce the weights of X and Y individually given that you have the starting weight of the compound XY.

Then, you need to find the number of moles of each part. If X was 0.05 moles and Y was 0.1 moles, then you know that the ratio Y:X is 2:1, and hence you can work out the formulae.

37
Q

How do you calculate the empirical formula?

A

1) Find the important information (masses of elements and atomic mass)
2) Work out the moles in each
3) Work out the mole ratio by dividing the number of moles by the smallest number
4) Write down the empirical formula

38
Q

How do you calculate the molecular formula?

A

Molecular formula = empirical formula x (RFM/empirical formula mass)

39
Q

How do you calculate reacting masses?

A

1) Balance the equation
2) Find the Mr of the compound/element whose weight you’ve been given
3) Calculate the moles in the given mass
4) Use the mole ratio from the equation
5) Find the mass of the unknown

40
Q

How do you calculate percentage yield?

A

Percentage yield = (actual yield/predicted yield) x 100

41
Q

What is the relationship between concentration, mols and volume?

A

concentration = mols/volume

42
Q

How are ions formed?

A

By gaining or losing electrons in a reaction

43
Q

What is oxidation?

A

The loss of electrons

44
Q

What is reduction?

A

The gain of electrons

45
Q

What is ionic bonding?

A

Strong electrostatic attraction between oppositely charged ions

46
Q

Why do ionic compounds have high melting and boiling points?

A

They have strong electrostatic forces between oppositely charged ions, which need a lot of energy to break.

47
Q

What is the relationship between ionic charge and the melting and boiling points of an ionic compound?

A

The more electrostatic bonds there are, the higher the melting and boiling points will be. For example magnesium oxide has a higher boiling point than sodium chloride.

48
Q

What is an ionic crystal?

A

A giant three-dimensional lattice structure held together by the attraction between oppositely charged ions

49
Q

How is a covalent bond formed?

A

The sharing of a pair of electrons between two non-metal atoms

50
Q

What is covalent bonding?

A

Strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond

51
Q

What is a common feature of simple molecular structures?

A

They are generally gases or liquids, sometimes solids with LOW melting points.

52
Q

Why do substances with simple molecular structures have low melting and boiling points?

A

The intermolecular forces are very weak, and do not require much energy to break.

53
Q

Why do substances with giant covalent structures have high melting and boiling points?

A

They have many strong covalent bonds, which need lots of energy to break.

54
Q

What is the structure of diamond?

A

Carbon atom has four others connected to it; tetrahedral structure

55
Q

What is the structure of graphite?

A

Carbon atom has three others connected to it, layers of hexagons

56
Q

Why is diamond used in cutting?

A

Diamond is very hard because it has lots of strong covalent bonds.

57
Q

Why is graphite used as a lubricant?

A

Graphite is formed in layers. There are weak intermolecular forces between the layers, so they easily slide over each other. It is slippery, and therefore makes a good lubricant.

58
Q

How can a metal be described?

A

A giant structure of positive ions surrounded by a sea of delocalised electrons

59
Q

Why can metals conduct electricity?

A

Delocalised electrons are free to move throughout the structure.

60
Q

Why are metals malleable?

A

Metals are malleable because their regular packing makes it simple for the atoms to slide over each other.

61
Q

What is an electric current?

A

flow of electrons or ions

62
Q

Why do covalent compounds not conduct electricity?

A

The molecules don’t have any overall electrical charge and there are no electrons mobile enough to move from molecule to molecule.

63
Q

Why do ionic compounds only conduct electricity when molten or in solution?

A

Ionic compounds don’t conduct electricity when they are solid, because they don’t contain any mobile electrons. However, when molten or in solution, the ions then become free to move around, and so they are able to conduct electricity.

64
Q

Describe an experiment to distinguish between electrolytes and non-electrolytes.

A

Set up an electric circuit with an LED and a break in the wire, put both ends of wire into a solution/molten substance. If the LED lights up then there is a current flowing, this will only be able to happen if the solution is conducting: so it must be an electrolyte. Conversely if the LED does not light up then there is no current flowing, and so the solution has not conducted electricity meaning it must be a non-electrolyte.

65
Q

What happens in electrolysis?

A

In electrolysis, ionic compounds conduct electricity. Positively charged ions move to one end, negatively to the other, these are then turned into atoms (by losing their charge) and so new substances are formed.

66
Q

Describe experiments to investigate electrolysis, using inert electrodes of molten salts and predict the products.

A

The products will be the two ions. The atom of the negative anion will be formed at the anode, and the atom of the positive cation will be formed at the cathode.

67
Q

Describe experiments to investigate electrolysis, using inert electrodes of aqueous solutions of ionic compounds, and predict the products.

A

In an aqueous solution, both hydrogen ions (H+) and hydroxide ions (OH-) are present. Use the order of discharge to predict the product formed at the anode (unless it is a halide ion, hydroxide will be formed) and if the metal is more reactive than hydrogen, then hydrogen will be formed at the cathode.

68
Q

What does one faraday represent?

A

One mole of electrons

69
Q

How do you calculate the amounts of the products of the electrolysis of molten salts and aqueous solutions?

A

1) Write out half equation
2) Find the charge using Q=It
3) Find the moles of electrons using n=Q/F
4) Use the mole ratio to work out how much substance there will be
5) Calculate the mass using Mrmols

GCSE Chemistry (5 decks)

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