Atoms + nuclear physics

Question 1

Where is most of the atoms mass

Answer 1

In the nucleus

Question 2

Charge

Answer 2

The number of electrons is equal to the number of proton so they have no overall charge (when the number changes they become ions either anions or cations)

Question 3

Rutherford’s Experiment

Answer 3

He fired alpha particles at gold foil and then detected the alpha particles after using a moveable detector and he found over 99% of the particles went straight through showing atoms are mostly empty space

Question 4

Nuclear fission process

Answer 4

One neutron is fired at a nucleus of an isotope (atom with more neutrons) the isotope splits and leaves three neutrons over which are fired at another three isotopes and the process repeats- each time the isotope splits energy is released as gamma radiation which heats water into steam which spins a turbine to produce electricity

Question 5

What 3 elements are used in fission

Answer 5

Uranium, plutonium and thorium

Question 6

Control rods

Answer 6

Control rods limit the number of neutrons by absorbing them so the reaction still occurs but doesn’t go into meltdown

Question 7

Concrete walls

Answer 7

Concrete walls absorb energy within the powerplant

Question 8

Isotopes

Answer 8

Atoms of the same element can have different numbers of neutrons

Question 9

Radioactive decay

Answer 9

Some atomic nuclei are unstable so the nucleus randomly gives out radiation as it changes to become more stable

Question 10

Atomic number

Answer 10

The number of protons in an element is its atomic number, it is the bottom number in notation

Question 11

Mass number

Answer 11

The total number of protons and neutrons in an atom is called the mass number, it is the top number in notation

Question 12

Background radiation

Answer 12

Radiation is around us constantly, coming from the ground (rocks), space (cosmic) and artificial sources (weapons or nuclear disasters)

Question 13

Activity

Answer 13

Activity is the rate a which a source of unstable nuclei decays

Question 14

Activity and time

Answer 14

Activity (Bq) decreases over time as more unstable nuclei decay

Question 15

Count rate

Answer 15

Count rate is the number of decays recorded each second by a detector (like a Geiger-Muller tube)

Question 16

Alpha particle

Answer 16

An alpha particle consists of two neutrons and two protons, it is the same as a helium nucleus

Question 17

Beta particle

Answer 17

A beta particle is a high speed electron ejected from the nucleus when a neutron turns into a proton

Question 18

Gamma ray

Answer 18

A gamma ray is a high energy electromagnetic wave

Question 19

Alpha charge, mass and symbol

Answer 19

Charge of +2, mass of 4, α

Question 20

Beta charge, mass and symbol

Answer 20

Charge of -1, mass of 0, β

Question 21

Gamma charge, mass and symbol

Answer 21

Charge of 0, mass of 0, γ

Question 22

Characteristics of the 3 types of radiation

Answer 22

Alpha is the most ionising and the least penetrating, travels 3-5 cm in the air and is stopped by paper- Beta is in the middle, can travel 10-100cm in the air and is stopped by aluminium, Gamma is the least ionising and the most penetrating with infinite range and is stopped by thick concrete

Question 23

Half- life

Answer 23

The time is takes for the mass, activity, count rate or number of nuclei to halve for a radioactive sample

Question 24

Contamination

Answer 24

The unwanted presence of a radioactive substance on or in other materials

Question 25

Irradiation

Answer 25

Exposing a material to alpha or gamma radiation