radioactivity

Question 1

radioactivity

Answer 1

The spontaneous breaking up of an
unstable nucleus with the emission of one
or more types of radiation

Question 2

who discovered radioactivity

Answer 2

Henri Becquerel

Question 3

Nonionizing radioactivity

Answer 3

Ultraviolet, visible, infrared, microwaves, radio & TV, power
transmission

Question 4

Ionizing – More Dangerous

Answer 4

Radiation capable for producing ions [bonds broken] when
interacting with matter – x-rays, alpha, beta, gamma, cosmic rays

Question 5

Which Elements Are Radioactive?

Answer 5

Most elements have radioactive isotopes BUT
any element with an atomic number greater
than 83 consists entirely of radioactive
isotopes

Question 6

what is the heaviest naturally occurring
element

Answer 6

Uranium is the heaviest naturally occurring
element – most elements above 92 are artificially
created in nuclear research facilities

Question 7

what did Pierre and Marie Curie do

Answer 7

–Purified pitchblende
–Discovered two new elements
* Polonium [after Poland] and
* Radium [giver of rays]

Question 8

Define alpha particles

Answer 8

Alpha particles are composite particles consisting of two protons and two neutrons tightly bound together. They are Thrown out by unstable radioactive nuclei until they become stable

Question 9

what is the charge of alpha particles

Answer 9

positive because they are attracted to negative charge

Question 10

what is Americium 241 used for

Answer 10

Americium 241 is used in smoke alarms

Question 11

what are alpha particles stopped by

Answer 11

Stopped by a few
cm of air or a sheet of paper

Question 12

what charge do beta particles have

Answer 12

negative because they are attracted to the positive plate

Question 13

define beta particles

Answer 13

high energy electrons Formed when a neutron is changed to form a proton plus an electron. Electron is then ejected from the nucleus.

Question 14

what can beta particles pass through

Answer 14

pass through paper
and up to about 5mm of Aluminium

Question 15

what does carbon-14 emit

Answer 15

beta particles

Question 16

give an example of an element that emits beta particles

Answer 16

carbon-14

Question 17

define gamma rays

Answer 17

High energy electromagnetic radiation. Pass straight through electric and magnetic fields so not charged.

Question 18

what stops gamma rays

Answer 18

only stopped by thick layer of lead

Question 19

What can gamma rays be used for

Answer 19

• Very dangerous carcinogenic
• Can also be used to cure cancer.
• Sterilising surgical instruments
• Cobalt-60 is a source.

Question 20

define Nuclear Reactions

Answer 20

Radiation is emitted from the nucleus

Question 21

Difference between nuclear reaction and chemical reaction

Answer 21

• Chemical reactions only involve electrons
  – no new elements involved
  – atoms only rearranged
• Nuclear reactions form a new element
  – what the alchemists tried to do.

Question 22

Transmutation

Answer 22

The changing of one element to another

Question 23

Isotopes

Answer 23

are atoms of an element
which have the same atomic
number [number of protons] but
different mass numbers due to
different numbers of neutrons

Question 24

Radio-isotopes

Answer 24

are isotopes which
are unstable and give out
radiation

Question 25

Half-Life

Answer 25

is the time taken for half of the nuclei in any given sample to decay

Question 26

how is the emission of half life?

Answer 26

purely random

Question 27

what do we use half life for

Answer 27

To compare rates of decay

Question 28

at what rate do radioactive isotopes decay at

Answer 28

Each radioactive isotope decays at its own
rate

Question 29

examples of half-lives

Answer 29

14 C 5700 years

60Co 5.26 years

234Po 0.15 milliseconds

Question 30

what messures radioactivity

Answer 30

Geiger-Muller tube