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Chemistry AS Rafa > 2.1 Atoms and Reactions > Flashcards

2.1 Atoms and Reactions Flashcards

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1
Q

Define relative atomic mass

A

The weighted mean mass compared with 1/12th mass of carbon-12

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2
Q

Define relative molecular mass.

A

The mass of a molecule is measured as the relative molecular mass by comparison with carbon-12.

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3
Q

Order of scientists that developed knowledge of the atom.

A

Democritus, John Dalton, Joseph John Thompson, Joseph John Thompson, Ernest Rutherford, Niels Bohr

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4
Q

What did Democritus do?

A

Developed the idea of ‘atomos’, meaning invisible in Greek. The idea that you would eventually reach a indivisible particle.

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5
Q

What did John Dalton do?

A

In 1808, he stated that:

  • atoms are tiny particles that make up elements
  • cannot be divided
  • all atoms of a given element are the same
  • atoms of one element are different to those of any other element
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6
Q

What did Joseph John Thompson do in 1898?

A

Discovered that cathode rays were a stream of particles with the following properties:

  • negative charge
  • deflected by both a magnet and an electric field
  • very small mass
  • cathode rays were electrons and so split and previous ideas were disproved
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7
Q

What did Joseph John Thompson do in 1904?

A

Develops idea that atoms are made of electrons scattered unevenly within an elastic sphere surrounded by positive charge - the plum pudding model.

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8
Q

What did Rutherford do?

A

In 1910, oversaw Geiger and Marsden fire helium nuclei at gold foil. Deflection. In 1911, he proposed that positive charge and most of its mass were at nucleus and negative orbit.

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9
Q

What did Bohr do?

A

He worked under Rutherford in 1913 and added that electrons are in orbits and that each orbital could have a set number of electrons. Explained spectral lines and different energy with distance from the nucleus.

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10
Q

What do we use mass spectroscopy for?

A
  • to identify an unknown compound
  • find the relative abundance of each isotope of an element
  • determine structural information about molecules
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11
Q

Define isotope.

A

Atoms of the same element with different numbers of neutrons and different masses.

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12
Q

Define relative isotopic mass.

A

Mass compared with 1/12 the mass of carbon-12.

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13
Q

What is the Avogadro constant?

A

Number of particles per mole. Number of atoms per mole of carbon-12 isotope.

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14
Q

Define empirical formula.

A

The simplest whole number ratio of atoms of each element present in a compound.

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15
Q

Define molecular formula.

A

The number and type of atoms of each element in a molecule.

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16
Q

Which atoms do not usually form ions?

A

Be, B, C and S

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17
Q

How many Pa is 1 atm?

A

101325 Pa

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18
Q

How many K is 0 degrees Celsius?

A

273

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19
Q

What is the value of the gas constant?

A

8.314 Jmol-1K-1

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20
Q

What is n equal to at RTP?

A

V/24

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21
Q

Percentage yield equation

A

Actual amount/theoretical amount

22
Q

Atom economy equation

A

Molecular mass of desired products/ sum of molecular masses of all products

23
Q

What are substances called that behave as both acids and bases?

A

Amphoteric substances

24
Q

What are amphoteric substances?

A

Substances that can behave as both acids and bases.

25
Q

What is water of crystallisation?

A

Water molecules that form an essential part of the crystalline structure of a compound.

26
Q

What is the oxidation number of peroxides?

A

-1

27
Q

Oxidation number of oxygen?

A

-2

28
Q

Oxidation number of hydrogen?

A

+1

29
Q

Oxidation number of metal hydrides?

A

-1

30
Q

What is a titre?

A

Final reading minus the initial reading.

31
Q

What are the main two indicators for acid/alkali reactions?

A

Methyl orange and phenolphthalein

32
Q

What does methyl orange do?

A

Turns yellow to red when adding acid to alkali.

33
Q

What does phenolphthalein do?

A

Turns pink to colourless when adding acid to alkali.

34
Q

Why is universal indicator not good for titrations?

A

The colour change is too gradual.

35
Q

What is the unknown solution in a titration known as?

A

The analyte.

36
Q

What is reaction stiochiometry?

A

How many moles of one reactant react with how many moles of another reactant.

37
Q

What are polyprotic acids?

A

Acids that donate more than one proton.

38
Q

Examples of a diprotic acid?

A

Sulphuric acid,carbonic acid and hydrogen sulfide.

39
Q

Give example of triprotic acid.

A

Phosphoric acid.

40
Q

Formula for carbonic acid?

A

H2CO3

41
Q

Formula for hydrogen sulfide?

A

H2S

42
Q

What is meant by one mole of substance?

A

Amount of substance which contains as many particles as there are carbon atoms in 12g of carbon-12

43
Q

What is used as the standard measurement of relative isotopic mass?

A

Carbon-12

44
Q

What happens to the oxidation state if a compound is oxidised?

A

Increases

45
Q

What happens to the oxidation state if a compound is reduced?

A

Decreases

46
Q

Units of pV=nRT?

A

p is Pa
V is m^2
T is in K

47
Q

Conversion from cm^3 to m^3

A

1 m3 = 1000 dm3 = 1 000 000 cm3

48
Q

Conversion from bar to Pa

A

1 bar = 100 kPa = 100000 Pa

49
Q

Conversion from atm to Pa

A

1 atmosphere = 101325 Pa

50
Q

Why does water have a concentration of 56 moldm-3?

A

1dm3 of water = 1000g

n=1000/18=56 moldm-3

51
Q

the benefits for sustainability of developing

chemical processes with a high atom economy

A

fewer natural resources and create less waste

52
Q

What are concordant titres?

A

within 0.1cm3

Chemistry AS Rafa (9 decks)

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