What Is Radioactivity? Flashcards
How is radiation measured
By the number of decays emitted per second
The radioactivity decreases with time
What happens when an atom decays during Alpha emission
An atom decays by ejecting an alpha particle (made of two neutrons and two protons) from the nucleus
A new atom is formed, this is a new element
In alpha emission when a new atom is formed, how is the new nucleus different form the old
It has two fewer protons and two fewer neutrons
The atomic number decreases by 2
The mass number decreases by 4
Why are alpha particles good ionisers
Alpha particles are good ionisers because they are relatively very big so hit atoms hard enough to strip off electrons
What happens when an atom is ionised
Electrons are stripped off leaving the atom positively charged (an ion)
What happens when an atom decays during Beta emission
An atom decays by changing a neutron into a proton and an electron
The electron is ejected as a beta particle
A new atom is formed, this is a new element
In beta emission when a new atom is formed, how is the new nucleus different form the old
It has one more proton and one less neutron
Atomic number increased by one
Mass number remains the same
Why are beta particles not good ionisers
Beta particles are not good ionisers as they are very light and cannot easily strip an electron from an atom
What is half-life
The time it takes for half the undecayed nuclei (in a radioactive substance) to decay
What is an alpha particle
Two protons and two neutrons like a helium nucelus
What is a beta particle
Fast moving electron
What is a gamma ray
An electromagnetic wave
How do radioactive materials give out nuclear radiation
They give out nuclear radiation from the nucleus of their atoms because they are unstable and decay naturally
