2.1 Flashcards

1
Q

Democritus

A

1st theory- divide a sample of matter only a certain amount of times, then it wouldn’t spilt any further

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2
Q

Dalton

A

2nd theory- atoms are tiny particles that make up elements and atoms cannot be divided
all atoms of a given element are the same, atoms of 1 element are different to every other element

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3
Q

J J Thomson

A

3rd theory (discovered cathode rays (electrons))
-electrons were negative charge and were a stream of particles
-they could be deflected by magnet and electric fields

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4
Q

J J Thomson’s model

A

Plum pudding and showed negative electrons around a sea of positive charge so overall charge of atom is equal

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5
Q

Rutherford’s Gold foil experiment 1911

A

directed alpha particles at thin gold foil, thought because of plum pudding, no alpha deflected

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6
Q

Results to Gold Fold experiment

A

-most weren’t deflected
-small percentage were
-very small value deflected back towards source

This showed there was a nucleus in centre, positive charge and electrons orbited around nucleus. Overall charge must be balanced

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7
Q

Niels Bohr discovery

A

Found electrons must orbit in certain paths otherwise they would spiral into nucleus

This helped to explain periodic properties such as, the energy of electrons is different distances from the nucleus

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8
Q

1918

A

Proton discovered

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9
Q

1932 James Chadwick

A

Neutron discovered

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10
Q

Protons and neutrons can be broken down into…

A

quarks

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11
Q

isotope

A

an atoms of the same element that have the same number of protons but different number of neutrons

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12
Q

why don’t diff isotopes of the same element react diff

A

as electrons are involved in chemical reactions not neutrons

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13
Q

relative atomic mass

A

the weighted mean mass of an atom of an element, compared with 1/12th of the mass of the atom of carbon-12

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14
Q

relative molecular mass

A

the weighted mean mass of a molecule, compared with 1/12th of the mass of an atom of carbon-12

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15
Q

relative isotopic mass

A

the mass of one atom of an isotope compared with 1/12th of the mass of an atom of carbon-12

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16
Q

relative formula mass

A

the weighted mean mass of a formula unit of a substance compared with 1/12th of the mass of an atom of carbom-12

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17
Q

metals (group 1-13) do they lose/gain

A

lose electrons — positive ion

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18
Q

non-metals (group 15-17) do they lose/gain

A

gain electrons —- negative ions

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19
Q

Be B Si and C all have what in common

A

none of them can form ion as it would require too much energy to transfer outer shell electrons

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20
Q

ionic formula overall charge

A

zero as +ions and -ions have to be balanced

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21
Q

amount of substance

A

the quantity that has moles as its units, used as a way to calculate atoms

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22
Q

mole

A

the amount of substance containing as many particles as there were carbon atoms in 12g of the carbon-12 isotope

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23
Q

molar mass

A

mass per mole of a substance in gmol-1

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24
Q

avogardo constant defintion

A

the number of atoms per mole of the carbon-12 isotope

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25
Q

empirical formula

A

simplest way of showing a chemical formula

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26
Q

molecular formula

A

not simplified formula, shows all the atoms that make up a molecule

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27
Q

standard concentration

A

has a known concentration

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28
Q

concentrated

A

large amount of solute per dm3

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29
Q

dilute

A

small amount of solute per dm3

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30
Q

percentage yield

A

actual amount in moles of product divided by theorical amount in moles of product

x100

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31
Q

atom economy

A

mr of the desired product divided by the sum of mr of all products

x100

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32
Q

what reactions have 100% atom economy

A

addition reactions

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33
Q

what reactions have less than 100% atom economy

A

reactions involving substitution or elimination

For us to use these types of reactions we need to find uses for all the products of the reaction

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34
Q

acid reacting with water

A

acid releases H+ ions and rest of atoms in acids make -ion

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35
Q

stronger acids

A

strong acids fully dissociate and easily gives up H+ ions

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36
Q

weaker acids

A

not good at giving up H+ ions and, and only partly dissociate. When they give away H+ ions they are quickly taken back

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37
Q

common bases

A

metal oxides and metal hydroxides

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38
Q

base

A

a proton H+ acceptor so neutralises acids

39
Q

acids

A

proton donor and releases H+ ions into a water

40
Q

alkalis

A

release OH- ions when dissolved in water

41
Q

acid and alkali reaction

A

OH- ions neutralise the protons from acid to form water

OH- (aq) + H+ (aq) = H2O (l)

42
Q

how we know if its a weak alkali

A

only a small proportion of dissolved alkali reacts with water- doesn’t release many OH- ions

43
Q

when equilibrum sign used in water and alkali reaction

A

shows weak alkali as reaction can go either way

44
Q

amphoteric substances

A

substances that can behave as acids and bases

eg. glycine as it contains COOH group (which will donate a proton) and NH2 group (will accept a proton)

45
Q

salt is an ionic compound with…

A

+ion (metal ion) and -ion (from acid)
Formula of salt is same as acid expect it can be any +ion

46
Q

acids reacting with carbonates

A

produces salt, C02 and H20

see bubbles of CO2
carbonates solid form in reaction

47
Q

acids reacting with metal oxide

A

salt and water formed

metal oxides are solid

48
Q

acids and alkali

A

both aq

salt and water formed

49
Q

acids and metals

A

metals are aq

salt and hydrogen gas formed
REDOX REACTION

50
Q

ammonia nitrate solution

A

found as two ions

NH4+
NO3-

51
Q

hydrated solution

A

the crystalline form containing water

52
Q

Anhydrous

A

the form containing no water

53
Q

water of crystallisation

A

refers to water molecules that form an essential part of the crystalline structure of a compound

if a compound crystalises in water, it becomes part of the crystalline structure

54
Q

CuSO4 . 5H20 what does the dot show?

A

dot acts as ratio, showing how many compound molecules to water molecules within a crystalline structure

The 5 is used within a formula

55
Q

in titration calculations you may be asked to find the …

A

-concentration of solution
- molar mass
-formula
-the number of molecules of water of crystallisation

56
Q

how to carry out a titration experiment

A
  1. using a pipette, add a measured volume of one solution (acid) to a conical flask
  2. Add a suitable indicator
  3. Place the other solution (alkali) to burette
  4. Then slowly add alkali into conical flask flask until the reaction has just been completed
    This is the end point
  5. Measure the volume of alkali added from the burette

Now know the volume of one acid that exactly reacts with the volume of one alkali
You can have acid in burette as well but less common and results in different colour changes if using phenolphthalein

57
Q

Identify end point in titration using indicator, what colours for methyl orange

A

Methyl orange - acid- red
-alkali (base)- yellow
-end point- orange

58
Q

Identify end point in titration using indicator, what colours for Bromothymol blue

A

acid-yellow
alkali- blue
end point- green

59
Q

Identify end point in titration using indicator, what colours for phenolphthalein

A

acid- colourless
alkali- pink
endpoint- pale pink
However if you added the acid by the burette and alkali was in conical flask then the end point would be colourless

60
Q

what are oxidation numbers used for

A

keep track of how electrons are being used in bonding

61
Q

what is an oxidations numbers

A

the number of electrons that an atom uses to bond with atoms of another element

62
Q

uncombined elements oxidation number

Just made up of one element eg. C or O2

A

zero as only one element

63
Q

If oxygen is combined with other elements, oxidation number?

A

-2

Except if a peroxide, eg: H2O2
then Oxygen = -1

Peroxide = any of a class of chemical compounds in which two oxygen atoms are linked together by a single covalent bond

64
Q

If hydrogen is combined with other elements, oxidation number ?

A

+1

Except if combined with metal hydrides then hydrogen = -1

Metal Hydrides= metals which have been bonded to hydrogen eg. LiH

65
Q

if fluorine is combined with other elements, oxidation number?

A

-1

66
Q

what happens to the oxidation numbers when fluorine bonds with oxygen

A

fluorine remains -1
oxygen becomes +2

67
Q

Groups 1,2,3 oxidation numbers if in combined with other elements

A

+1,+2,+3

68
Q

what is chlorines oxidation number if combined with other elements

A

-1

69
Q

the sum of oxidation numbers is compounds must equal?

A

zero

70
Q

the sum of oxidation numbers in molecular ions must equal?

A

the charge of the ion

71
Q

TRUE/ FALSE
transition metals form ions with different oxidation numbers

A

true

72
Q

FeCl2 oxidation number of Fe

A

+2

73
Q

FeCl3 oxidation number of Fe

A

+3

74
Q

Cu2O oxidation number of Cu

A

+1

75
Q

CuO oxidation number of Cu

A

+2

76
Q

Oxyanions

A

negative ions that contain an element as well as oxygen

77
Q

TRUE/FLASE
Element forms oxyanions and then has different oxidation numbers?

A

true

78
Q

NO2- oxidation number of N

A

+3

79
Q

NO3- oxidation number of N

A

+5

80
Q

SO3^2- oxidation number of S

A

+4

81
Q

SO4^-2 oxidation number of S

A

+6

82
Q

Oxidation and Reduction

A

OIL RIG

83
Q

oxidation

A

loss of electrons, gain of oxygen

84
Q

reduction

A

gain of electrons, loss of oxygen

85
Q

half equations for oxidation

A

start with element then after arrow have ion and electrons-

Mg arrow Mg2+ + 2e-

86
Q

half equations for reduction

A

start with element and electrons- then after arrow put ions you produced

Cl2 + 2e- arrow 2Cl2-

87
Q

metals and non-metals oxidised and reduced

A

metals tend to be oxidised
non-metals tend to be reduced

88
Q

reduction with oxidation number

A

decreases number

89
Q

oxidation with oxidation number

A

increase number

90
Q

metal and acid redox reactions
which is red and oxd

A

reduction-hydrogen in acid (this forms H2 gas product)
oxidised- metal

91
Q

concentration of solution

A

amount of solute dissolved in a given amount of solvent

92
Q

in titration fill up to…

A

meniscus

93
Q

titration flask used…

A

volumetric flask

94
Q

How to make a standard solution

A
  1. weigh out the solute
  2. completely dissolve the solute in solvent in a beaker
  3. transfer the solution to a volumetric flask and rinse the beaker using more solvent and add rinsing’s to flask
  4. add more solvent carefully to bottom of the meniscus. may need to use drop by drop method to get exact measure on meniscus
  5. mix solution several times by inverting flask several times