Atoms and Radioactivty

Question 1

Why do isotopes have different physical properties ?

Answer 1

Diff in mass and stabilty of nucleus

Question 2

What are protons held together by in the nucelus ?

Answer 2

Nucelur force

Question 3

How is it strong ?

Answer 3

It is strong enough to hold the nucleus together against the electric force repelling the protons away .

Question 4

What does unstable nuclei form ?

Answer 4

When they decay ,they give out ionising radiation cause atoms to lose or gain charge forming ions .

Question 5

3 types of decay ?

Answer 5

Alpha ,Beta ,Gamma rays

Question 6

What are alpha particle ?

Answer 6

Alpha radiation consists of fast moving particles that are thrown out of unstable nuclei when they decay .\
Helium nuceli
Mass no of 4
Charge - +2

Question 7

Mass/charge of alpha

Answer 7

relative large mass - mass no of 4 and charged because of two protons they carry - +2

Question 8

Range of alpha ?

Answer 8

Short range
Cannot penetrate far
They interact with atoms along their path causing ions to form
Rapidly give up the energy when they r ejected from unstable nucleus

Question 9

What is beta radiation ?

Answer 9

Fast moving electrons ejected by a decaying nucleus .

Question 10

Why r electrons involved in beta ?

Answer 10

In beta minus - a neutron splits into a proton and an electron .Proton remains in nucleus while electron is ejected at high speed as a beta minus particle .

Question 11

Mass of beta

Answer 11

Very light

Question 12

Range of beta

Answer 12

Interact with material in their path less frequently than alpha particles
They are smaller and carry less charge .

Question 13

Gamma rays

Answer 13

Electromagnetic waves with short wavelengths

Question 14

Range /Mass

Answer 14

No mass
No charge
Weekly ionising and interact occasionally .
Extremely penetrating .

Question 15

Relationship between ionising power and penetrating power

Answer 15

Inversely proportional

Question 16

What is neutron radiation ?

Answer 16

Neutrons are emitted by radioactive material
If emitted - mass no goes down by 1
If absorbed - mass no goes up by 1
ATM no - unchanged

Question 17

Alp-ha decay

Answer 17

Constant ius HE - mass is 4 and atm no is 2 and energy

Question 18

Beta -1 decay

Answer 18

Atomic no add 1
Electron - mass -0
electron - —1 atm no

Question 19

Neutron decay

Answer 19

textbook

Question 20

Gamma decay

Answer 20

after it has emiited a alpha or beta
it has surplus energy
it emits this energy as gamma radiation

Question 21

What is a GM tube made of ?

Answer 21

It is a
glass tube with an electrically conducting surface on the inside. The tube has
a thin window made of mica The tube contains a special mixture of gases at very low pressure.
In the middle of the tube, electrically insulated from the conducting surface,
there is an electrode. This electrode is connected, via a high-value resistor, to
a high-voltage supply, typically 300-500 V.

Question 22

How does a GM tube work ?

Answer 22

When ionising radiation enters the tube it causes the low pressure gas inside
to form ions. The ions allow a small amount of current to flow from the
electrode to the conducting layer. This is detected by an electronic circuit.
The GM tube is usually linked up to a counting circuit. This keeps a count of
how many ionising particles (or how much y radiation) have entered the GM
tube. Sometimes GM tubes are connected to rate meters. These measure
the number of ionising events per second, and so give a measure of the
radioactivity in becquerels. Rate meters usually have a loudspeaker output so
the level of radioactivity is indicated by the rate of clicks produce

Question 23

What is half life ?

Answer 23

Length of time it takes for the activity of a radioactive substance to halve

Question 24

What is nuclear fission reaction ?

Answer 24

the process of splitting a nucleus is called nuclear fission. ● when a uranium-235 nucleus absorbs a thermal (slow-moving) neutron, it splits into two daughter nuclei and 2 or 3 neutrons, releasing energy in the process. ● the neutrons then can induce further fission events in a chain reaction by striking other uranium-235 nuclei

Question 25

What is nuclear fusion reaction ?

Answer 25

The process of fusion two nuclei to form a larger nucleus is called nuclear fusion. ● There is a very small loss of mass in the process, accompanied by a release of energy. ● Nuclear fusion is how the sun and other stars release energy. ● Nuclear fusion does not happen at low temperatures and pressures because the electrostatic repulsion of the protons is too great.