nuclear physics

Question 1

what provided evidence for distribution of mass in an atom

Answer 1

The scattering of alpha particles by thin metal foil

Question 2

what makes up the mass number

Answer 2

protons +neutron

Question 3

define nuclear fission

Answer 3

the splitting of a large and unstable nucleus and the release of energy.

Question 4

which 2 isotopes are most commonly undergo fission and are used in nuclear powerplants

Answer 4

uranium and plutonium

Question 5

what must happen for fission to occur

Answer 5

uranium-235 or plutonium-239 nucleus must first absorb a neutron to make the nucleus unstable.

Question 6

what happens in nuclear fission

Answer 6

nucleus must first absorb a neutron to make the nucleus unstable. The nucleus undergoing fission splits into two smaller nuclei, releasing two or three neutrons and energy.

Question 7

which reaction (chemical or nuclear) release move energy involving a similar mass of material.

Answer 7

nuclear

Question 8

when do chain reactions occur

Answer 8

A chain reaction occurs when neutrons from the fission go on to cause further fission

Question 9

what do control rods in nuclear reactors do

Answer 9

absorb fission neutrons to ensure that on average only one neutron per fission goes on to produce further fission and energy transfer.

Question 10

why is waste from nuclear reactions an issue

Answer 10

radioactive nature and may remain so for a long time, depending upon its half life and products

Question 11

whats a factor that may influence the use of nuclear power to generate energy

Answer 11

The disposal of radioactive waste needs to be managed with care

Question 12

define nuclear fusion

Answer 12

the joining of two light nuclei to form a heavier nucleus.

Question 13

what happens in nuclear fusion

Answer 13

some of the mass of the smaller nuclei is converted into energy.

Question 14

what are the conditons needed for nuclear fusion

Answer 14

The force of repulsion between the two positive nuclei must be overcome for them to get close and fuse and this happens at very high temperatures and pressures

Question 15

how does nuclear fusion contribute to the solar system

Answer 15

Nuclear fusion is the process by which energy is released in stars

Question 16

whats the general word equation for nuclear fusion

Answer 16

deterium+deterium->helium +energy

Question 17

what do nuclear fission and fusion have in common

Answer 17

they both release energy

Question 18

what is the random process od radioactive decay

Answer 18

some atomic nuclei are unstable. The nucleus emits particles or radiation and the nucleus changes to that of a different element and becomes more stable

Question 19

define backround radiation

Answer 19

radioation present all around the environment

Question 20

whatre the 4 natural sources of radiation

Answer 20

-internal from food
-building materials
-food
-soil
-gamma rays

Question 21

whatre the 4 artificial sources of radiation

Answer 21

-medical
-nuclear weapon testing
-discharge from nuclear power plants
-air travel

Question 22

what does the gieger muller tube do

Answer 22

detects radiation then sends implusee to counting machine when it absorbs radiation then makes a clicking sound and displays count rate

Question 22

what type of radiation does the gieger muller tube measure

Answer 22

ioninsing radiation

Question 23

whats irradiation

Answer 23

the process of exposing an object to ionizing radiation.

Question 24

what happens when an object becomes irradiated

Answer 24

it doesnt become radioactive

Question 25

what is contamination and why is it a hazard

Answer 25

the unwanted presence of radioactive atoms on other materials. The hazard from contamination is due to the decay of the contaminating atoms.

Question 26

The most unstable nuclei have the ____ half-lives

Answer 26

shortest

Question 27

whats the patern of decay

Answer 27

rapid and spontaneous with a lot of radiation emitted in a short time.

Question 28

what is half-life

Answer 28

-the average time it takes for the number of nuclei of the isotope in a sample to halve
-the time it takes for the count rate from a sample containing the isotope to fall to half its initial level.

Question 29

whatre the 4 things we can do to minimise irradiation

Answer 29

-wear gloves
-wear overalls
-use tongs to pickup material
-lead-lined boxes