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Chemistry > C4 > Flashcards

C4 Flashcards

1
Q

Give 4 facts about the nucleus of an atom

Charge, location, size, mass, contains

A

? Positive
? In the middle of the atom
? Contains protons and neutons
? Almost the whole mass of the atom is concentrated in the nucleus

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2
Q

Give 4 facts about electrons

Charge, location, size, mass

A

? Negatively charged
? Move around the nucleus in electron shells
? They’re very small, but cover a lot of space
? Have virtually no mass

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3
Q

What are the charges and masses of the following?

a) Protons
b) Neutrons
c) Electrons

A

Protons: Charge = +1 Mass = 1
Neutons: Charge = 0 Mass = 1
Electrons: Charge = ?1 Mass = 0.0005

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4
Q

Why do neutral atoms have no charge overall?

A

Because they have the same number of protons as electrons

the charge on the electrons is the same size as the charge on the protons but opposite so they cancel out

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5
Q

What is the top number of an atom?
Eg 23
Na
11

A

The mass number

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6
Q

What does the mass number tell us?

A

The number of protons and neutrons

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7
Q

What is the bottom number of an atom?
Eg 23
Na
11

A

The atomic number

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8
Q

What does the atomic number tell us?

A

The number of protons

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9
Q

What are the verticle columns of the periodic table called?

A

Groups

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10
Q

What does the group of an element correspond to?

A

The number of electrons it has in its outer shell

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11
Q

What are the rows of the periodic table called?

A

Periods

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12
Q

What does the period to which the element belongs to correspond to?

A

The number of shells of electrons it has

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13
Q

What are isotopes?

A

Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons
Eg. Carbon 12 (6p,6e, 6n) and Carbon 14 (6p, 6e, 8n)

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14
Q

What happens in ionic bonding?

A

Atoms lose or gain electrons to form charge particles (ions) which are then strongly attracted to each other

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15
Q

What does ionic bonding occur between?

A

A metal and a non?metal

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16
Q

Explain the structure ionic compounds form

A

Produce giant ionic structures = the ions form a closely packed regular lattice arrangement. The ions are not free to move and so do not conduct electricity. There are very strong chemical bonds between the ions

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17
Q

Give two examples of giant ionic structures

A
  1. MgO = Magnesium Oxide

2. NaCl = Sodium Chloride

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18
Q

Why do magnesium oxide and sodium chloride have high melting and boiling points?

A

They have a very stong attraction between the oppositely charged ions in the structures and so to break the bonds you need lots of energy to overcome the forces of attraction

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19
Q

Why does magnesium oxide have a higher melting point than sodium chloride?

A

? It’s made of Mg(2+) and O(2?) ions which have double the charge of Na(+) and Cl(?) ions so the attraction is harder to overcome.
? Also O(2?) ions are smaller than Cl(?) ions so the ions in MgO can pack together more closely = attraction harder to overcome

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20
Q

What happens when metals form ions?

A

They lose electrons to form positive ions

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21
Q

What happens when non?mentals form ions?

A

They gain electrons to form negative ions

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22
Q

How do you work out the charge on the ion?

A

It is the same as the number of electrons lost or gained
Eg. If two electrons are gained then the charge is ?2
Eg. If three electrons are lost, the charge is +3

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23
Q

What is covalent bonding between?

A

Two non?metal atoms combine by sharing pairs of electrons

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24
Q

Why are the melting points and boiling points of simple molecular structures formed from covalent bonds usually very low?

A

Because the forces between the molecules are very week and are easily parted from each other

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25
Q

Why don’t molecular substances conduct electricity?

A

Don’t have free electrons or ions

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26
Q

What metals are in group 1?

A

Lithium, sodium, Potassium, Rubidium, Caesium and Francium

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27
Q

What happens to the reactivity as you go down the alkali metals?

A

Reactivity increases because the outer electron is more easily lost because it’s further from the nucleus so less energy is needed to remove it

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28
Q

Why are the alkali metals very reactive?

A

They all have one outer electron

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29
Q

What 3 physical properties do the alkali metals share?

A
  1. Low melting points and boiling point
  2. Low density
  3. Very soft
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30
Q

Will the alkali metals form covalent or ionic compounds?

A

They are keen to lose the oiter electrons to form a 1+ ion with a stable electronic structure

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31
Q

What is oxidation?

A

The loss of electrions

32
Q

Explain what happens when lithium, sodium or potassium are put in water

A

React vigorously: move around the surface, fizz, produce hydrogen
Potassium = hot enough to ignite it
Sodium and potassium = melt in the heat

33
Q

What forms when lithium, sodium or potassium are put in water? Give a balanced symbol equation

A

An alkali forms which is the hydroxide of the metal

2Na + 2H(2)O = 2NaOH + H(2)
Sodium + Water = Sodium hydroxide + Hydrogen

34
Q

How do you do a flame test to identify the alkali metal that is present?

A
  1. Dip wire loop into hydrochloric acid to clean and moisten

2. Put the loop into powdered compound and place in blue bunsen flame

35
Q

What colours will be produced in a flame test from:

a) Lithium?
b) Sodium?
c) Potassium?

A

a) Red
b) Yellow/orange
c) Lilac

36
Q

What elements are in group 7 (Halogens?

A

Fluorine, chlorine, bromine, iodine, astatine

37
Q

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

A

It decreases because there’s less inclination to gain the extra electron to fill the outer shell when it is further away from the nucleus

38
Q

What happens to the melting and boiling points of the halogens as you go down the group?

A

They increase

39
Q

What are the properties of these elements at room temperature

a) Chlorine?
b) Bromine?
c) Iodine?

A

a) A dense green, poisonous gas, fairly reactive
b) A dense, poisonous orange liquid
c) A grey crystalline solid

40
Q

Why are the halogens keen to gain an electron?

A

To form a 1? ion with a stable electronic structure

41
Q

What is reduction?

A

The gain of electrons

42
Q

What do the Halogens and the alkali metals react together to form?

A

Salts called ‘metal halides’

43
Q

Why do all metals have the same basic properties?

A

Metals are held together by metallic bonds that allow the outer electron(s) of each atom to move freely. This creates a sea of delocalised electrons which gives the properties.

44
Q

What properties do all metals have? (6 points)

A
  1. Hard, dense and lustrous
  2. High melting/boiling points because of strong metallic bonds
  3. Strong attraction between the delocalised electrons and the closely packed positive ions (strong metallic bonding)
  4. The strength of the metallic bond decreases as the atomic radius increases
  5. Malleable
  6. Good conductors of heat
45
Q

What metal is used to make saucepans? What are its properties?

A

Stainless steel
? Good conductor of heat
? Doesn’t rust easily

46
Q

What metal is used to make electrical wiring. What are it’s properties?

A

Copper
? Good conductor of electricity
? Easily bent

47
Q

What metal is used to make planes? What are it’s properties?

A

Aluminium
? Low density (light)
? Strong
? Doesn’t corrode

48
Q

What metal is used to make bridges? What are it’s properties?

A

Steel

? Strong

49
Q

What happens if you make some metals very cold?

A

Their resistance disappears and becomes a superconductor

50
Q

Why do you want the resistance of the metal to disappear?

A

None of the electrical energy is turned into heat so none of it’s wasted

51
Q

What 3 things can be made with superconducting wires?

A

1) Power cables that transmit electricity without any loss of power
2) Strong electromagnets that don’t need a constant power source
3) Electronic circuits that work very fast

52
Q

How cold do metals have to be made before they become a superconductor?

A

?265 degrees celcius

53
Q

What are the 2 disadvantages of superconducting metals?

A

? Expensive to get to the low temperature

? Very hard to reach the temperature

54
Q

What are the metals in the middle of the periodic table called?

A

Transition metals

55
Q

Give a use of

a) Iron
b) Nickel

A

a) Catalyst in the haber process

b) Useful for the hydrogenation of alkenes

56
Q

What compounds do

a) Iron (III) make?
b) Iron (II) make?
c) Copper make?

A

a) Orange/brown
b) Light green
c) Blue

57
Q

What do transition metal carbonates break down into when heated?

A

A metal oxide and carbon dioxide

Resulting in a colour change

58
Q

How can you check if the gas given off is carbon dioxed?

A

By bubbling it through limewater and if CO(2) is present it turns milky

59
Q

What is a precipitation reaction?

A

Where two solutions react and an insoluble solid forms in the solution

60
Q

Give the word and symbol equation for the reaction between copper (II) sulfate and sodium hydroxide

A

CuSO(4) + 2NaOH = Cu(OH)(2) + Na(2)SO(4)

Copper(II) sulfate + sodium hydroxide = copper(II) hydroxide + Sodium sulfate

61
Q

How can you test for transition metal ions?

A

Using precipitation because some insoluble transition metals have distinctive colours

62
Q

What 3 uses does water have in industry?

A

A cheap raw material, a coolant and a solvent

63
Q

What two sources do we get our water from in the UK?

A

a) Surface water eg. lakes, rivers and reservoirs

b) Groundwater eg. aquifers (rocks that trap water underground)

64
Q

Why are groundwater and surface water limited?

A

They depend on annual rainful

65
Q

How is water from surface water sources purified? (3 points)

A
  1. Filtration
  2. Sedimentation
  3. Chlorination
66
Q

Explain filtration

A

A wire mesh screens out large twigs etc

Sand and gravel beds filter out any other solid bits

67
Q

Explain sedimentation

A

Iron sulfate or ammonium sulfate is added to the water making fine particles clump together and settle at the bottom

68
Q

Explain chlorination

A

Chlorine is bubbled through to kill harmful bacteria and microbes

69
Q

What impurites can tap water still contain? What consequences do they have?

A

1) Nitrate residues from excess fertiliser. Prevent the blood carrying oxygen properly. Serious health problems, especially for children
2) Lead compounds from old lead pipes. Very poisonous, especially for children
3) Pesticide residues from spraying near to rivers/lakes

70
Q

What is another option to get fresh water?

A

Distilling sea water

71
Q

What are two disadvantages of distilling sea water?

A

Needs a lot of energy and is therefore expensive.

It is not practical for producing large quantities of fresh water

72
Q

How can you test for dissolved ions in water?

A

Using precipitation reactions

73
Q

What is the test for sulfate ions?

A

1) Add dilute hydrochloric acid to test sample
2) Add 10 drops of barium chloride solution
3) White precipitate = sulfate ions

74
Q

Give the symbol and word equation for sulfate ions and barium ions

A

Barium ions + sulfate ions = Barium sulfate

Ba (2+) + SO(4) (2?) = BaSO(4)

75
Q

What is the test for halide ions?

A
  1. Add dilute nitric acid to the test sample
  2. Add 10 drops of silver nitrate solution
  3. Chloride ions present = white precipitate
    Bromide ions present = cream precipitate
    Iodide ions present = pale yellow precipitate
76
Q

Give the word and symbol equation for silver nitrate and sodium chloride

A

Silver nitrate + sodium chloride = silver chloride + sodium nitrate

AgNO(3) + NaCl = AgCl + NaNO(3)

Chemistry (8 decks)

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