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Chemistry A2 > Elements Of Life 🌲 > Flashcards

Elements Of Life 🌲 Flashcards

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1
Q

What is an isotope?

A

Same atomic number and a different mass number

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2
Q

What is the plum pudding model?

A

The cell is a circle with mainly positive charged “pudding” and negative “plums” dotted around

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3
Q

How was the plum pudding model proved wrong?

A
  • alpha particles fired at sheet of gold
  • were expecting alpha partciles to be reflected back at odd angles
  • went straight through though.
  • some went back 90° too
  • nucleus in the centre
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4
Q

How was the neutron discovered?

A
  • realisation that nucleus heavier than just protons

- must be other stuff in there

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5
Q

What are relative masses?

A

Masses of atoms compared to carbon-12

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6
Q

What is a mole?

A

Amount of a substance

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7
Q

Moles=?

A

Particles you have/ avogadros constant

Mass/ mr

Conc x volume

Vol/ 24

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8
Q

What is an empirical formula?

A

The smallest ratio

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9
Q

How do you do water of crystallisation?

A
  1. Moles water lost
  2. How many moles in the anhydrous salts
  3. Do the ratio: mol anhydrous/ mol water
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10
Q

Percentage yield=

A

(Actual/ theory) x 100

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11
Q

Vol to use=

A

(Final conc/ initial conc) x vol required

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12
Q

In an acid/ base titration, when do you know what indicator to use?

A

Methyl orange= yellow to red when adding acid to alkali

Phenolphthalein= red to colourless when acid to alkali

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13
Q

What is spin pairing?

A

Electrons in the same orbital spin in opposite directions

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14
Q

What is an ionic bond?

A

When ions are stuck together by electrostatic attraction.

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15
Q

What behaviours do ions do?

A
  1. Conduct electricity
  2. High MP as strong electrostatic attraction
  3. Soluble in water as polar
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16
Q

What is a covalent bond?

A

Shares electrons

17
Q

Covalent bond properties

A

Fairly low MP and BP
Cant conduct electricity
Water insoluble

18
Q

How do properties of ionic lattice provide evidence for covalent bonding?

A
  • high MP
  • hard
  • good thermal conductivity
  • wont dissolve
  • cant conduct electricity
19
Q

What makes the biggest angles and what makes the smallest?

A

LP/ LP biggest angles

BP/ BP smallest

20
Q

Tetrahedral bond angle

A

109.5°

21
Q

Trigonal pyrimidal

A

107°

  • 1 LP
  • 3 BP
22
Q

Bent shape

A
  1. 5°
    - 2 LP
    - 2 BP
23
Q

Trigonal planar

A

120°

  • 3 BP
  • 0 LP
24
Q

Trigonal bipyrimidal

A

120° & 90°

  • 5 BP
  • 0 LP
25
Q

Octahedral

A

90°

  • 6 BP
  • 0 LP
26
Q

Periodic trends

A
  • CD increased across the group

- first ionisation enthalpies decrease down the group and increase across a period

27
Q

What is the first ionisation enthalpy?

A

Energy needed to remove 1 electron from each atom in 1 mol gaseous atoms to form 1 mole gaseous +ve ions.

28
Q

What affects the size ionisation enthalpies?

A
  1. Electron shielding
  2. Atomic radius
  3. Nuclear charge
29
Q

Group 2 reactions?

A
  • with water to make hydroxides

- burn in oxygen to make oxides

30
Q

Thermal stability in group 2 carbonates

A
  • increases down the group
  • carbonates large anions and can be made unstable by cations
  • makes the carbonate polarise itself
  • the greater the distortion the less stable the carbonate ion
  • large cations = less distortion as they have a lower CD. Larger cations are down the group
31
Q

What are salts?

A

Formed from positively charged cations and negative anions so the product is neutral

32
Q

Solubility rules?

A
  • group 1 and ammonium salts soluble
  • nitrates soluble
  • group 7 soluble apart from silver halides
  • sulphates soluble
  • most hydroxides and carbonates insoluble
33
Q

How do you make insoluble salts?

A
  1. Precipitation
  2. Pick 2 solutions that contain the ions that you need
  3. Filter
34
Q

Making soluble salts?

A
  1. Pick an acid, plus an insoluble base
  2. Metal oxide will dissolve as acid reacts.
  3. Filter out the excess metal
  4. Evaporation of water
35
Q

Making soluble salts using an alkali?

A
  1. Need to add the correct amount of alkali to neutralise the acid.
  2. Use a titration
  3. Use an indicator
  4. Evaporation of water
36
Q

What happens when electrons absorb energy

A
  • get excited to a higher energy level
  • electrons release energy by dropping from a higher energy level
  • energy levels are quantised
37
Q

What is absorption spectra?

A

Dark lines coloured background

  • E= hv
  • electrons only absorb energy with correct frequency for the energy level
  • means frequencies of light missing
38
Q

What is emissions spectra?

A

Bright lines coloured background

- when electrons drop energy levels frequencies given out

Chemistry A2 (8 decks)

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