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Chemistry A-Level > EL 1, 2 > Flashcards

EL 1, 2 Flashcards

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1
Q

`why are models useful / not useful

A
  • they are useful because they help explain observations
  • they are not useful because they cannot be considered as the truth
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2
Q

what are the names and charges of each of the subatomic particles that make up an atom

A
  • proton +1
  • neutron 0
  • electron -1
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3
Q

what are the locations of each of the three types of subatomic particles

A
  • proton, makes up the nucleus
  • neutron, makes up the nucleus
  • electrons, orbit the nucleus
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4
Q

what are the masses of each of the subatomic particles

A
  • proton, 1
  • neutron, 1
  • electron, 0.00055
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5
Q

what is the atomic number of an atom

A

(Z)
- the number of protons in the nucleus
- is numerically equal to the charge

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6
Q

how do you calculate mass number

A

atomic number (Z) + number of neutrons (N)

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7
Q

define isotope

A

atoms of the same element with different mass numbers

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8
Q

what is the relative atomic mass of an element

A
  • since most elements naturally exist as a mixture of isotopes
  • relative atomic mass is an average of all the relative isotopic masses taking their abundances into account
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9
Q

how do mass spectrometers work

A
  • the sample atoms or molecules are ionised to positively charges cations
  • the ions are separated according to their mass to charge ratios
  • separated ions are detected together with their relative abundance
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10
Q

describe the process of nuclear fusion

A

two light, atomic nuclei fuse together to form a single heavier nucleus of a new element, releasing enormous quantities of energy
- at normal temperatures on the Earth, the positive nuclei repel strongly
- at much higher temperatures (in a star) the nuclei move much more quickly and collide with so much energy that the repulsion is overcome

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11
Q

what is spectroscopy

A
  • the study of how light and matter interact
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12
Q

what are the names of the two models used to describe the behaviour of light

A
  • the wave theory
  • the particle theory
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13
Q

describe the wave theory of light

A
  • it’s one form of electromagnetic radiation
  • light behaves like a wave with characteristics wavelength and frequency
  • a wave of light travels the distance between two points in a certain time
  • speed of light is the same for all waves of different wavelengths
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14
Q

what is different about light of different colours

A
  • it has different wavelengths and therefore different frequencies
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15
Q

how are frequency and wavelength related

A

wavelength (m) X frequency (^-1) = speed of light

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16
Q

define the particle theory of light

A
  • easier to explain by thinking of the waves as particles
  • light is a stream of photons (tiny packets of energy)
  • energy of the photons is related to position of light in the electromagnetic spectrum
17
Q

how do you calculate energy of a photon

A
  • Energy of a photon = planck constant X frequency
18
Q

what is the value of Planck constant

A

6.63 X 10^34

19
Q

why can a hydrogen atom only emit a limited number of specific frequencies

A
  • when an atom is excited, electrons jump to a higher energy level
  • later they drop back down to lower energy levels and emit the extra energy as electromagnetic radiation giving off an emission spectrum, giving am emisison spectrum
20
Q

what happens when white light is passed through a cool sample of a gaseous element

A
  • black lines appear
  • the black lines that appear in the absorption spectrum correspond to light absorbed by the atoms
21
Q

what do the intensities of of the lines on the atomic spectra correspond to

A
  • the abundance of the elements
22
Q

what were the main parts of Bohr’s theory

A
  • the electron in the hydrogen atom only exists in definite energy levels
  • a photon of light is emitted or absorbed when the electron changes energy levels
  • the energy of the photon is equivalent to the difference between energy levels
  • E = hv so frequency of the emitted or absorbed light is related to the energy by thus equation
23
Q

what does it mean that the electrons energy is quantised

A
  • the energy of an electron cannot change continuously
  • it isn’t able to change to any value
  • only the definite values that are allowed
24
Q

what’s the name of of the electrons lowest energy level, and what happens as the energy levels get further from the nucleus

A
  • the ground state
  • energy levels increase
25
Q

describe the Lyman series

A
  • frequencies of the lines of the Lyman series correspond to changes in electronic energy from various upper levels to one common lower level
26
Q

what does Bohr’s theory explain

A
  • explains how you get an absorption spectra and emission spectra
  • gives scientists a model for the electronic structure of atoms
  • lent support to the new quantum theory
27
Q

what are the ions for the following elements and the corresponding flame colours:
- lithium
- sodium
- potassium

A
  • Li+ bright red
  • Na+ yellow
  • K+ lilac
28
Q

what are the ions and the corresponding flame colours for the following elements:
- calcium
- barium
- copper

A
  • Ca2+ brick red
  • Ba2+ apple green
  • Cu2+ blue green
29
Q

why are flame tests carried out

A
  • used to identify the presence of a metal in a sample

Chemistry A-Level (26 decks)

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