isotopes and ionising radiation

What is an isotope

Atoms with the same number of protons but different number of neutrons

What does atom contain what are the mass,charges

Protons - +1 charge relative mass-1

Neutrons - neutral relative mass - 1

Electrons- -1 charge. Relative mass 1/2000

On element describe which number represents the atomic number and the mass number

The atomic number = number of protons and is the bottom number

The mass number = total of protons and neutrons together and is top number

Number of protons and electrons are the same

Describe what happens in radioactive decay

-only one or two of an elements isotopes are stable and the other isotopes which are unstable decay into other elements by emitting radiation (alpha/beta/gamma) or sometimes neutrons we call this process radioactive decay

What point are electrons said to be excited

Electrons are arranged in a series of energy levels (shells). With each shell getting progressively further away from the nucleus and increasing energy level.

Electrons can occasionally jump onto a higher energy level if they gain enough energy at this point we say that the electron have become excited. The energy for this sometimes comes from electromagnetic radiation.

What does process of electrons getting excited only work due to

If the radiation carries just the right amount of energy to get the electron from one energy level to the next.

Soon after the electron will fall back down to the lower energy level and remit the energy to electromagnetic radiation.

Describe the process of ionisation

the outermost electron absorbs so much energy that is able to completely leave the atom, this leaves the atom with more protons than electrons so it’s left with a positive charge which means we now create a positive ion rather than an atom

Extra note

Ionising radiation - able to know electrons off atoms

What is alpha particle and describe its structure

alpha particles are helium nuclei.

Alpha particles are made up of two protons and two neutrons. Alpha particles don’t have any electrons to have an overall charge of 2+.

Why can’t alpha particles penetrate far

Because they are relatively large our particles are easily stopped by collisions with other molecules mean they can’t penetrate very far into other materials. They can only travel a few centimetres in the air and absorbed by single sheet of paper.

Why are alpha particles strongly ionising

the large size and strong charge makes them very strongly ionising (can easily knock off electrons off atoms they collide with).

Why do isotopes undergo radioactive decay

To become more stable as only one or two of the elements Isotopes are stable and the rest are unstable so have to undergo radioactive decay whether they admit something so they can change slightly to become a stable

Xtra note

A radioactive material – just consists of unstable isotopes that can decay

Describe what a beta particle is and its structure

Peter particles are fast moving electrons and have a charge of -1 and virtually no mass

state how ionising a beta particle is and why

And state where it can penetrate far

beta particles are moderately ionising because they are relatively tiny. They can penetrate moderately far into materials ,it will take 5 mm of aluminium to stop them or a few metres in the air.

State what happens for every beta particle emitted

/ inset as of electrons being emitted from one of atoms shells what happens

For every beta particle emitted, a neutron in the nucleus has turned into a proton

Electrons are emitted from one of the atom shells. Instead one of the atoms neutrons decay into a proton and an electron. the proton stays in the nucleus, but the electron is admitted out at high speed.

What are gamma rays

Waves of electromagnetic radiation released by the nucleus, often omitted after alpha or beta radiation

Why are gamma rays weakly ionising and penetrate far into materials

Because gamma rays don’t have any mass or charge, they tend to pass straight through materials rather than colliding with any of the atoms making them weakly ionising. This means they can penetrate really far into materials.

What does it take for gamma rays to be stopped

Thick sheets of lead or multiple sheets of concrete(metres)

Describe the emission of a neutron

If the nucleus contains too many neutrons which is making it unstable it can just throw out a neutron to increase its stability