Radioactivity

French physicist ? investigated radiation of uranium salts.

Henri Becquerel

Henri Becquerel investigated

radiation of uranium salts.

Radioactivity is defined as the:

spontaneous random decay of an unstable nucleus emitting alpha, beta and (or) gamma particles.

Pierre and Marie Curie studied ? in more detail.

They won the ? in physics and chemistry.

radiation of uranium

Nobel prize

The Nature of Radioactive Radiation

- Three types of radiation:

alpha, beta and gamma.

Alpha particles:

- Consist of ? same as ?

2 protons and 2 neutrons

nucleus of helium

Alpha particles:

they carry a

double positive charge.

Alpha particles:

- Relatively large ?

mass

Alpha particles:

- Relatively large mass so they travel the ? compared to the other two types.

slowest

Alpha particles:

they have the ? power. A ? can stop them.

least penetrating

sheet of paper

Alpha particles:

- ? emits alpha particles (used in ?).

Americium -241

smoke detectors

Alpha particles:

- Alpha particles are not considered dangerous as

they cannot penetrate the skin.

Beta particles

- These are

fast moving electrons.

Beta particles

- A neutron in an unstable nucleus changes into ?.

a proton and an electron

Beta particles

The electron is ? from the nucleus.

ejected

Beta particles

- neutron ->

proton + electron

Beta particles

- Beta particles are ? than alpha particles so travel ? therefore are ? than alpha particles.

lighter

faster

more penetrating

Beta particles

- Can penetrate up to ?

5 millimetres of aluminium.

Beta particles

- ? emits beta particles.

This is used to ?

known as ?

Carbon-14

find the age of certain substances

carbon dating.

Beta particles

Radioactivity is defined as the:

spontaneous random decay of an unstable nucleus emitting alpha, beta and (or) gamma particles.

Gamma radiation

- These are ?

high energy electromagnetic radiation.

Gamma radiation

- Does not consist of ?, it is not deflected in ?

charged particles

electric or magnetic fields.

Gamma radiation

- ? penetrating ability. Only stopped by ?

Very high

thick lead.

Gamma radiation

- Cobalt-60 is used in ?

radiotherapy.

Gamma radiation

- Most dangerous of the three. ?.

Cancerous

Radiation detection

- A Geiger-Muller tube is used to

detect radioactivity.

Nuclear Reactions:

A process that alters the composition, structure or energy of an atomic nucleus.

Transmutation:

The changing of one element into another.

The half life of an element is

the time taken for half of the nuclei to decay.

Half - Life

The half - life of elements are

- Temperature and pressure have ? effect on half life.

unique and can vary hugely.

no

A radioisotope is a

radioactive isotope.

Radioisotope uses:

Medical:

Gamma rays can kill cancerous cells (radiotherapy)

Radioisotope uses:

Smoke alarms:

Americium - 241 (alpha) is used in smoke alarms. Half life is 432 years.

Radioisotope uses:

Archaeological:

Carbon dating by using isotope carbon 14 (beta).

Chemical reaction

Involves electrons rather than

nucleus

Chemical reaction

No

new element formed

Chemical reaction

No release of

nuclear radiation

Chemical reaction

Chemical bonds ?

broken and formed

Nuclear reaction

Changes take place ? and ? are not involved

inside the nucleus

electrons

Nuclear reaction

A ? is formed

new element

Nuclear reaction

? is released

Nuclear radiation

Nuclear reaction

? broken or formed

No chemical bonds