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physics > P4 > Flashcards

P4 Flashcards

1
Q

What is the size of the radius of an atom?

A

1×10^-10 m

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2
Q

What is in the nucleus of an atom?

A

Protons (+) and neutrons (neutral)

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3
Q

What is around the nucleus of an atom?

A

Electrons (-) In energy levels

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4
Q

How does distance from nucleus affect energy levels?

A

Energy levels which are further from the nucleus are at higher energy than those close

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5
Q

What happens if an atom, absorbs electromagnetic radiation

A

An electron can move from a lower energy to a higher energy level temporarily

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6
Q

What is the atomic number and what does it tell us?

A

23
— Na
11 ————> atomic number
= number of protons,electrons

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7
Q

What is the mass number and what does it tell us?

A

23 ———> mass number
— Na = number of protons
11. +Neutrons

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8
Q

How do we calculate number of neutrons in an atom?

A

Mass number - the atomic number

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9
Q

What are isotopes?

A

Isotopes are atoms of the same element that have different numbers of neutrons

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10
Q

What are ions?

A

charged Atoms that lost or gained electrons from the outer energy level

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11
Q

What is the plum pudding model?

A

An atom is a ball of positive charge with negative electrons embedded in it

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12
Q

What is the alpha scattering experiment?

A

scientist, got a piece of gold foil and fired tiny particles (alpha particles of gold) at it

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13
Q

What did the Alpha scattering experiment tell us?

A

-Atoms are mainly empty space most alpha particles went straight through the gold
-Due to some of the atoms deflecting atoms must have a positive charge
-Due to some alpha particles bouncing back, the mass of an atom must be concentrated in the centre

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14
Q

What did James Chadwick discover?

A

The nucleus also contains neutrons

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15
Q

What is radioactive decay?

A

When an isotope gives out radiation from the nucleus to become stable

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16
Q

What is activity?

A

The activity is the rate at which is sort of unstable, nuclei decay
1 Bq = 1 decay per second

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17
Q

How do we measure the activity of a radioactive source?

A

Geiger - muller tube

18
Q

What is count rate?

A

The count rate is the number of decays recorded each second by detectors such as Geiger-Müller tube

19
Q

What are the four types of radiation released by an unstable nucleus?

A

-Alpha(2 proton 2 neutron)same as helium
-Beta particle (Electron injected from nucleus at very high speed)
-Gamma rays (electromagnetic radiation from nucleus)
-neutron

20
Q

Where is a beta particle formed?

A

Inside the nucleus, when a neutron turns into a proton and electron

21
Q

What is the range in air between alpha particles?

A

Alpha particles are very large, they travel 5 cm before colliding with air

22
Q

What is the range in air of beta particles?

A

Beta particles travel 15cm

23
Q

What is the range in air between gamma rays?

A

Gamma rays can travel several metres

24
Q

What is the penetrating power of alpha particles?

A

Alpha particles are stopped by a single sheet of paper

25
Q

What is the penetrating power of beta particles?

A

Beta particles are stopped by a few millimetre of aluminium

26
Q

What is the penetrating power of gamma rays?

A

Gamma rays radiation is stopped by several centimetres of lead

27
Q

What is the ionising power of alpha particles?

A

Alpha particles are very strongly ionising

28
Q

What is the ionising power of beta particles?

A

Beta particles are quite strongly ionising

29
Q

What is the ionising power of gamma rays?

A

Gamma rays are weakly ionising

30
Q

What is ionising power?

A

When radiation collides with atoms ,that can cause loss of electrons and form ions

31
Q

What happens during alpha decay?

A

Atomic number decreases by 2 mass number decreases by 4

32
Q

Happens during beta decay

A

Atomic number increases by one and mass number does not change

33
Q

What happens during gamma decay?

A

Nothing both the atomic number and mass number ate not changed

34
Q

What is a half life?

A

time taken for
-number of nuclei to decrease by half
-count rate decrease by half

35
Q

What is irradiation?

A

Exposing an object to nuclear radiation a good example is sterilisation

36
Q

What is the risk to humans of ionising radiation?

A

Ionising radiation can increase risk of cancer

37
Q

What can we use as shielding (protection) against alpha beta and gamma rays?

A

For alpha rays, we can use gloves for beta and Gamma rays we can use lead apron and lead

38
Q

What is radioactive contamination?

A

When unwanted radioactive isotope end up on other materials

39
Q

Why is contamination hazardous?

A

Atoms decay, and emit ionising radiation

40
Q

What is peer review?

A

Studies are published in the scientist, allowing findings to be checked for legitimacy

41
Q

what is an alpha particle

A

2 charged atoms, 2 neutral atoms

42
Q

what charge does beta particles have

A

negative

physics (8 decks)

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