Chapter 11: Atoms and Radioactivity

Gamma rays

________ are least ionizing because they are uncharged.

Nuclear radiation

________ can damage or destroy living cells, and stop organs in the body working.

Central nucleus

________ made up of protons and neutrons.

Nuclear fusion

________ is how the sun and other stars release energy.

burst of gamma

An amplifier and loudspeaker- loudspeaker makes a click when each particle or ________ particle is received.

atomic number

As a proton has replaced a neutron in the nucleus, the ________ rises to 54.

unstable nuclei

The emission of an alpha or beta particle makes ________, stable; but alters the number of protons and neutrons in it.

ions

Atoms become ________ when they lose (or gain) electrons.

Protons

________ and neutrons are called nucleons.

Radon

________ has an atomic number of 86, so ________ is the new element formed as shown below:

ratemeter

A(n) ________ gives reading in counts per second.

daughter nucleus

The ________ and any emitted particles are the decay products.

Uranium 235

When a(n) ________ nucleus absorbs a neutron, it splits into two daughter nuclei and 2 or 3 neutrons, releasing energy in the process.

greater charge

They have a(n) ________, so exert more forces on electrons.

Isotopes

________ are elements /atoms /atomic number which have same number of protons and electrons but different number of neutrons.

disintegration of nucleus

The ________ is called radioactive decay.

Beta

________ and gamma rays are most harmful because they can penetrate to internal organs.

particles

The ________ and waves radiate from the nucleus which is called nuclear radiation.

antineutrino

The electron and ________ leave the nucleus at high speed.

Gamma emission

________ by itself causes no change in mass number or atomic number.

Alpha Particle

________ are more ionizing than Beta Particles.

Electrons

________ re held in orbit by he force of attraction between opposite charges.

Number of particles

________ depend on the type of atom.

half life of a radioactive isotope

The ________ is the time taken for half the nuclei present in any given sample to decay.

Materials

________ which emit nuclear radiation are radioactive materials.

Nuclear radiation

________ can remove electrons from atoms in its path, so it has an ionizing effect.

Uranium 235

________ is a commonly used isotope as the fuel in nuclear reactors.

An amplifier and loudspeaker

loudspeaker makes a click when each particle or burst of gamma particle is received

Define isotope.

One of two or more atoms of an element with the same atomic number but with different numbers of neutrons.

Define alpha.

The emission of helium nuclei that consist of 2 protons and 2 neutrons (thus having a +2 charge) and can be stopped by a piece of paper.

Define beta.

A neutron breaks into a proton (which remains in the nucleus) and releases a fast moving electron. These particles can be stopped by 3 mm aluminium sheet.

Define gamma.

A high energy electromagnetic wave. Having no mass and no charge its ionising power is very low but Its penetrating power is very high (about 99.9% is absorbed by 1 km of air or 10 cm lead).

Define background radiation.

The nuclear radiation that arises naturally from cosmic rays and from radioactive isotopes in the soil and air.

What is ionization?

It is the process by which a neutral atom gains or loses an electron thereby becoming an ion.

What is half life?

The time taken for half the atoms in a sample to decay into another substance

What is radioactive decay?

A spontaneous process in which unstable nuclei lose energy by emitting radiation.

Define nuclear fission.

The splitting of the nucleus of a large atom into two or more fragments; releases additional neutrons and energy.

Define nuclear fusion.

The process by which nuclei of small atoms combine to form a new, more massive nucleus; the process releases energy.

What is the ionizing radiation level of alpha particle?

It is the most ionizing.

What is the ionizing radiation level of gamma?

It is the least ionizing.

What is the penetrating level of gamma?

It is the most penetrating.

What is the penetrating level of alpha?

Skin/Paper/ a few cm of air stops this type of radiation.

What is the penetrating level of beta?

Aluminium / 50cm of air stops this type of radiation