Nuclear Nat 5

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Why is radiation emitted from atoms?

Because there nucleus is unstable. Due to the proton to neutron ratio.

A alpha particle consists of…

2 protons and 2 neutrons: it is a a helium atom.

Beta radiation is described as …

A high speed electron

Gamma radiation is described as …

A wave

Alpha is stopped by…Thin paper and a few cm of air.

Beta is stopped by…Thick lead, concrete and Aluminium.

Gamma is stopped by…Concrete or lead.

6g of a radioactive isotope of 60Co has a half-life of 5 yrs. how much of this isotope would be left after 20 yrs?

The half life of a radio active isotope is a measure of the time is takes for activity to be reduced by half. Over a period of 20 years, 4 half-lives would be needed .

60Co 60Co 60Co 60Co 60Co

6g 3g 1.5g 0.75g 0.375g

What is the result of an atom losing an alpha

particle?

An alpha particle is a helium nucleus. So is made up from 2 protons and 2 neutrons. It has a atomic number of 2 and a mass number of 4. So the atomic number decreases by 2 and the mass number decreases by 4.

What type of reaction is occurring in the process below?

Nuclear fission this involves the splitting of a nucleus into two nucleui.

3

920

1U

236+

56

Ba 142

36

Kr 91

+

What is produced (X) when 238U

is combined with a neutron.

Adding a neutron means the mass number willincrease by 1, but the atomic number will not change.

n 01

U 238+

e -1

0+X

X =93

Pu 239

131I can be used to study diseased thyroid glands. Its half-life is 8 days. A patient was given 0.0053 mol of this isotope. How many grams would be left after 16 days?

The mass of 131I in 0.0053g = n (number moles) = mass/gfmSo mass = n x gfm = 0.0053x131 =0.694g

131I 131I 131I

0.694g 0.347g 0.174g

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