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gcses > physics topic four > Flashcards

physics topic four Flashcards

1
Q

what did John Dalton do

A

Discovered atoms

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2
Q

what did JJ Thomson do

A

Discovered electrons

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3
Q

what did Ernest
Rutherford discover

A

Atoms made of a positive nucleus with
electrons orbiting it.

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4
Q

what did Neils Bohr do

A

Showed that electrons are found in shells

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5
Q

what did James Chadwick do

A

Discovered neutrons

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6
Q

what was discovered in the Alpha particle scattering experiment

A

-Most alpha particles passed straight through therefore most of an atom is empty space

-Some particles were deflected therefore the nucleus is positive (so repels positively charged alpha particles)

-Very few particles bounced back therefore a nucleus is a concentrated small mass

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7
Q

give features of nuclear model of atom

A

Mass + Positive charge - Concentrated in the middle (nucleus)

Electrons - Orbit the nucleus
in shells

Space - Mostly empty space

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8
Q

give features of plum pudding model of atom

A

Mass + Positive charge -Distributed around the atom

Electrons - Embedded in
structure

Space - solid mass

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9
Q

what are isotopes

A

Isotopes are atoms of the same element with the SAME number of protons and a DIFFERENT number of neutrons

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10
Q

how do isotopes that are unstable become stable

A

Some atomic Isotopes are unstable and emit radiation so they become more stable this process is called Radioactive Decay.

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11
Q

what are the three types of radiation

A
  • Alpha α
  • Beta β
  • Gamma γ
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12
Q

give a description of alpha radiation

A

2 Protons and
2 Neutrons

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13
Q

give description of beta radiation

A

High energy Electron

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14
Q

give description of gamma radiation

A

High energy Electromagnetic
radiation

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15
Q

describe Penetration power of alpha radiation

A

Stopped by paper
or few cm’s of air

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16
Q

describe Penetration power of beta radiation

A

Stopped by few
mm’s of Aluminium

17
Q

describe Penetration power of gamma radiation

A

Stopped by cm’s of
lead or metres of
concrete

18
Q

describe Ionising effect of alpha radiation

A

Strongly Ionising

19
Q

describe Ionising effect of beta radiation

A

Weakly Ionising

20
Q

describe Ionising effect of gamma radiation

A

Very Weakly
Ionising

21
Q

what are the effects of
magnetic/ electric fields on alpha radiation

A

Weakly deflected

22
Q

what are the effects of
magnetic/ electric fields on beta radiation

A

Strongly deflected

23
Q

what are the effects of
magnetic/ electric fields on gamma radiation

A

No deflection

24
Q

describe the effects of gamma radiation on electrons

A

Electromagnetic radiation absorbed by the electron causes it to move to a higher energy level (shell)

Electron can emit
electromagnetic radiation causing it to return to its original
energy level (shell)

25
Q

How does radiation kill you

A

Alpha, beta and gamma radiation collide with DNA,
ionise them (removes electrons), mutating them, giving you cancer

26
Q

how does low dose radiation effect cells

A

normal cells exposed to low dose radiation

ionisation inside cell leads to damage

damaged (mutant) cells divided uncontrollably forming a tumour

27
Q

how does high does radiation effect cells

A

higher doses tends to kill cells completely, Which causes radiation sickness if lots of cells are killed at once

28
Q

what is the half life

A

The half-life is the time taken for the number of radioactive
nuclei in an isotope to half

29
Q

describe irradiation vs contamination

A
  • Irradiated objects have been exposed to radiation and are NOT radioactive
  • Contaminated objects give off radiation as they have been contaminated with radioactive
    particles.
30
Q

how to stay safe when dealing with radioactive sources

A
  • Use tongs and gloves at all times
  • Don’t look directly at the radioactive source
31
Q

what is background radiation

A

Background radiation is radiation that is found all
around us at all times.

32
Q

give examples of background radiation

A
  • (medical) x-rays
  • radiotherapy
  • nuclear weapons (testing)
33
Q

describe Nuclear Fusion

A
  • Light nuclei
  • Fuse to make heavier nuclei
  • Some mass converted to energy
34
Q

describe Nuclear Fission

A
  • Neutron absorbed by an unstable uranium nucleus
  • Nucleus splits into 2 daughter nuclei, 3 neutrons, gamma rays and energy
  • Neutrons go on to react with more Uranium nuclei
35
Q

how are control rods used in a nuclear reactor

A
  • Absorb neutrons
  • Slowing down the reaction
  • Releases less energy

gcses (16 decks)

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