4.4.2.2 Nuclear equations

How small is an atom?

Atoms are extremely small, having a radius of about 1 x 10-10 m

what is a nuclear equation

to show alpha and beta decay

How small is the nucleus?

Of course much smaller than the atom, the radius of a nucleus is less than 1/10 000 of the radius of the atom. Most of the mass is in the nucleus.

Where are the electrons?

The electrons are arranged around the nucleus and are at different distance from the nucleus (energy levels). Absorption and emission of electromagnetic radiation causes electrons to move between different energy levels.

What effect does absorption of electromagnetic radiation have on the distance an electron is from the nucleus?

It causes electrons to move further away as they move to higher energy levels. They move back down when electromagnetic waves are emitted.

What does it mean if something is radioactive?

If an atom is radioactive it means it emits (gives out) ionising radiation or particles.

Why would an atom be radioactive?

Protons and neutrons are held together in the nucleus by strong nuclear forces, this ‘binding energy’ holds the nucleus together.
This force is stronger in stable nuclei to overcome the electrostatic force of repulsion between the protons and also to stop the neutrons from moving away from the nucleus.

How does an unstable nucleus lose mass and energy to become more stable?

By emitting particles and or energy

alpha particle structure

An alpha particle consists of 2 protons and 2 neutrons.
An alpha particles relative mass is 4 and relative charge is +2
same as helium

how to represent alpha particles symbol

alpha decay diagram

Which subatomic particles, and how many of each, are emitted from the nucleus of a uranium atom during alpha decay, to form an alpha particle?

An atom decays into a new atom and emits an alpha particle (2 protons and 2 neutrons)
Alpha radiation is the same as the nucleus of a helium atom travelling at extremely high speed.

How has the mass number of the element changed during decay?

The atomic number decreases by 2 and the mass number by 4

How has the atomic (proton) number changed during decay?

The atomic number decreases by 2 and the mass number by 4

How would the charge of the element’s nucleus be affected?

The positive charge of the nucleus decreases by 2

what happens during beta radiation

a neutron changes to a proton and electron

the electron is ejected from the nucleus (the beta particle)

alpha decay of radium 226 Ra 88

rules for alpha decay

the atomic number decreases by 2
the mess number decreases by 4

beta decay rules

atomic number increases by 1

mass number does not change

charge increases by 1

what is gamma decay

atomic number and mass number has no change

what is gamma radiation

Gamma radiation is a high energy, high frequency wave.

Gamma radiation has no mass and no charge as it is wave.

1\.What is being emitted in __**Gamma radiation**__?

An electromagnetic gamma wave

general equation for beta decay