Physics P4 ( Atomic Structure)

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What is the radius of an atom?
1 x 10^-10m
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What is the basic structure of an atom?
A positiviely charged nucleus with protons and neurons surrounded by negatively charged electrons
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What is the radius of a nucleus compared to the radius of an atom?
1/10,000
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Where is most of the mass of an atom concentrated?
In the nucleus
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How might electron arrangements change with the absorption of electromagnetic radiation?
moves further from the nucleus meaning a higher energy level
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How might electron arrangements change with the emission of electromagnetic radiation?
moves closer to the nucleus meaning a lower energy level
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What is the number of protons also equal to the number of in an atom?
Electrons
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What is an atoms overall charge?
None
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What does the nucleus give out as it changes to become more stable?
radiation
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Is radioactive decay a random or intended process?
random
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Define activity
The rate at which a source of unstable nuclei decays
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What is activity measured in ?
becquerels (Bq)
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Define count rate
The number of decays recorded each second by a detector (like a Geiger-Muller tube)
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What 3 types of nuclear radiation can be emitted? ( 4th one is a sub-atomic particle)
Alpha, beta, gamma and neutron
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What is an alpha particle? ( what nucleus of an element is the same as this)?
A particle that has 2 neutrons and 2 protons, the same as a helium nucleus
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What is a beta particle?
A high speed electron ejected from the nucleus as a neutron turns into a proton
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What is a gamma ray?
It is electromagnetic radiation form the nucleus
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What is the order of range in air that the 3 radiations can do?( shortest to longest)(cm)
Alpha (3-5), Beta (about 15), Gamma (much longer)
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What is the order of ionising power of the 3 radiations?(weak to strong)
Gamma, Beta, Alpha
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can alpha pass through paper, 5 cm of aluminium and 5cm of lead??
no,no,no
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can beta pass through paper, 5 cm of aluminium and 5cm of lead??
yes,no,no
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can alpha gamma through paper, 5 cm of aluminium and 5cm of lead??
yes,yes,no(but some will still get through)
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how does alpha decay change the mass and charge of an atom?
causes both the mass and charge of the nucleus to increase
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how does beta decay change the mass and charge of an atom?
mass doesn't change, charge increases
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Which radiation does not cause the mass or charge if a nucleus to change?
gamma
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Define half-life of a radioactive isotope
The tine it takes for the number of nuclei of the isotope to half, or the tine it takes for the count rate(activity) to half of its initial level
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What is radioactive contamination?
The unwanted presence of materials containing radioactive atoms on other materials.
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Where does the hazard of contamination come from?
The decay of the contaminating atoms
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What is irradiation?
The process of exposing an object to nuclear radiation.
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Which one of these 2 doesn't become radioactive?
Irradiation
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What type of review should happen when scientists publish findings on the study of the effects of radiation on humans?
peer review
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Where does background radiation come from?
Natural sources (rocks and cosmic ray form space), Man-made sources (fallout form nuclear weapons testing and nuclear accidents)
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What 2 ways are nuclear radiations used in medicine?
exploration of internal organs, control/destruction of unwanted tissue
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What is nuclear fission?
The splitting of a large and unstable nucleus(like uranium or plutonium)
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What must the unstable nucleus first absorb for fission to occur?
A neutron
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What happens next?
The nucleus splits into 2 smaller nuclei, equal in size, and emits 2 or 3 neutrons plus gamma rays
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Is energy absorbed or released in nuclear fission?
released
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What type of energy do the products have?
Kinetic energy
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What may the neutrons go on to start?
A chain reaction
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How are chain reactions controlled?
By a nuclear reactor
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what is an explosion by a nuclear weapon caused by?
An uncontrolled chain reaction
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What is nuclear fusion?
The joing of 2 light nuclei to form a heavier nucleus
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What may some of the mass be converted into in the process of nuclear fusion?
The energy of radiation
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Other cards in this set

Card 2

Front

What is the basic structure of an atom?

Back

A positiviely charged nucleus with protons and neurons surrounded by negatively charged electrons

Card 3

Front

What is the radius of a nucleus compared to the radius of an atom?

Back

Preview of the front of card 3

Card 4

Front

Where is most of the mass of an atom concentrated?

Back

Preview of the front of card 4

Card 5

Front

How might electron arrangements change with the absorption of electromagnetic radiation?

Back

Preview of the front of card 5
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