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AS Chemistry > 1.2 - Basic ideas about atoms > Flashcards

1.2 - Basic ideas about atoms Flashcards

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1
Q

What is the mass and charge of a proton?

A

1, +1

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2
Q

What is the mass and charge of a neutron?

A

1, 0

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3
Q

What is the mass and charge of an electron?

A

1/1840, -1

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4
Q

What is an atomic number (z)?

A

Number of protons in the nucleus of an atom. Bottom number on PT

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5
Q

What is a mass number? (a)

A

Number of protons and nuetrons in the nucleus of an atom. Top number of PT

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6
Q

What is an isotope?

A

Atoms with the same number of protons but different neutrons

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7
Q

What is an ion?

A

Particle where number of electrons does not equal number of protons

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8
Q

What happens if an atom loses an electron?

A

It forms a positive ion or cation.
Na - Na+ + e-

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9
Q

What happens if an atom gains an electron?

A

It forms a negative ion or anion
Cl +e- - Cl-

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10
Q

What is radioactivity?

A

Where some isotopes are unstable and split into smaller atoms. Process is called radioactive decay, and the nucleus gives off alpha, beta and gamma.

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11
Q

Fact file of alpha.

A
  • 2 protons and 2 neutrons, helium nuclei
  • least penetrating, most ionising
  • stopped by a sheet of paper or a few cm of air
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12
Q

Fact file of beta

A
  • streams of high energy electrons
  • mid penetration, mid ionisation
  • travels 1m in air, stopped by 5mm aluminium.
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13
Q

Fact file gamma.

A
  • high energy electromagnetic waves
    -highly pentrating, least ionising
  • can pass through several cm of lead, m of concrete.
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14
Q

What is ionisation?

A

Transfer of energy from the radiation passing through the matter to the matter itself.

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15
Q

What happens when radiation passes through an electric field?

A

gamma is undeflected
beta towards positive charge
alpha towards negative charge

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16
Q

What happens when radiation passes through a magnetic field?

A

Force called ‘motor effect’
gamma is undefleted (neutral
charge)
beta is deflected (negative charge)
alpha is deflected (positive charge)

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17
Q

What happens to elements met with alpha radiation?

A
  • mass number decreases by 4, atomic number decreases by 2
  • product is 2 places to the left on PT
    238/92 U —- 234/90 +4/2 A
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18
Q

What happens to elements met with beta radiation?

A
  • mass number is unchanged, atomic number increases by 1
  • product is 1 place right on PT
    14/6 C — 14/7 + 0/-1B
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19
Q

What happens to elements met with inverse beta radiation?

A
  • aka electron capture
  • one of the electrons is captured by a proton in the nucleus, forming a neutron and emitting an electron nuetrino (ve)
  • 1 place left on PT
  • 40/19K + e- —— 40/18Ar
    ‘inverse’ to beta decay.
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20
Q

What happens to elements met with positron emission or B+ decay radiation?

A
  • proton is converted into a neutron, releasing a positron (B+) and one electron neutrino (Ve)
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21
Q

What is half life?

A

The time taken for half the atoms in a radioisotope to decay or the time taken for the radioactivity of a radioisotope to half its initial value.

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22
Q

What 2 questions can be asked about half life?

A

Mass and time calculations

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23
Q

What can ionisation do to cells?

A

Damage the DNA in a cell, leading to mutations and replications of cancerous cells.
Outside the body, gamma is the most dangerous, inside the body alpha is the most deadly.

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24
Q

Medical benefits of radioactivity?

A
  • cobalt-60 is used in treatment for cancer
  • technetium-99m used as a tracer
25
Q

Radio-dating benefits of radioactivity?

A

-carbon-14 used to calculate age of plants and animal remains
- potassium 40 is used to estimate geological age of rocks

26
Q

Analysis benefits of radioactivity?

A
  • dilution analysis, used to find mass of substances in a mixture
  • measuring the thickness of metal strips or foil
27
Q

What are shell numbers known as?

A

Principal quantum numbers, n.
Lower the value of n, the closer the shell to the nucleus, lower the energy level.

28
Q

What is an atomic orbital?

A

Region of an atom that can hold up to 2 electrons with opposite spins (reduces the effect of repulsion)

29
Q

What do s orbitals looks like?

A

1 type, a circle

30
Q

What do p orbital look like?

A

3 types, dumbell shapes on different axis

31
Q

How many electrons can s,p, d and f hold?

A

s - 2
p - 6
d - 10
f - 14

32
Q

What is the Aufbau principle?

A

Electrons fill atomic orbitals in order of increasing energy.

33
Q

What is the Pauli exclusion principle?

A

Maximum of 2 electrons can occupy any orbital each with opposite spins.

34
Q

What is Hunds rule?

A

The orbitals will first fill one electron each will parallel spins, before a second electron is added with the paired spin.

35
Q

4th energy rule?

A

4s subshell filled before 3d.

36
Q

What is ionisation energy?

A

The process of removing electrons from an atom is called ionisation. The energy needed to remove each successive electron from an atom is called first second ect IE.

37
Q

First IE equation?

A

x(g) – x+ (g) +e-

38
Q

What 3 rules come with ionisation energy?

A

1) The size of the positive charge (increased charge, increased IE)
2) The distance of the outer electron from the nucleus (increased nuclear distance, decreased IE)
3) The shielding affect by electrons in filled inner shells (decreases IE because of repulsion)
4) paired vs non paired (pairing decreases IE)

39
Q

What is successive ionisation energy?

A

Measure of the energy needed to remove each electron in turn until all the electrons are removed from an atom.

40
Q

Why does successive ionisation energy always increase?

A
  • there is greater effective nuclear charge as the same number of protons are holding fewer electrons
    -as each electron is removed, there is less repulsion so shells will be drawn closer to nucleus.
  • as the distance of each electron decreases, the nuclear attraction increases.
41
Q

What is light a form of?

A

Electromagnetic radiation

42
Q

How are waves described?

A

Frequency (f) and wavelength (y)

43
Q

What is the equation for the speed of light?

A

C - fy

44
Q

What is the equation for energy?

A

e=hf (h is plancks constant)

45
Q

Name the 6 types of waves.

A

Gamma, xray, ultraviolet, infrared, microwaves and radiowaves.

46
Q

Where is visible light located on the electromagnetic spectrum?

A

between ultraviolet and infrared waves.

47
Q

What are the black lines on an absorption spectra?

A

Atoms and molecules absorb light of certain wavelengths, causing the black lines.

48
Q

What do the lines on a absorption spectra correspond to?

A

The energy taken in by the atoms to promote electrons from lower to higher energy levels.

49
Q

What is an emission spectra?

A

When a source of energy is removed from the atoms, they fall from the higher energy level to a lower one and energy lost is released as a photon (a quantum of light energy) with a specific frequency (the coloured lines)

50
Q

Why does hydrogen have the simplest emission spectrum?

A

An atom of hydrogen only has one electron.

51
Q

What is the hydrogen spectrum?

A

electrons can jump energy levels when subjected to energy, and can fall back down, emitting energy in the form of electromagnetic radiation, these form the lines of the spectrum.

52
Q

What is the energy of emitted radiation equal to?

A

Difference between the energy levels.

53
Q

What happens when the frequency of the hydrogen spectrum increases?

A

The lines get closer together because the energy difference between the shells decreases.

54
Q

What series has electrons n=1?

A

The lyman series

55
Q

What series has electrons n=2?

A

The balmer series

56
Q

What series has electrons n=3?

A

The paschen series

57
Q

What is the convergence limit?

A

when an electron is no longer quantised by the nucleus, losing control and atom becomes ionised.

58
Q

Convergence limit of Lyman?

A

Represents the ionisation of a hydrogen atom.

AS Chemistry (15 decks)

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