Physics - Radioactivity Flashcards
(45 cards)
What is the diameter of an atom?
1x10^-10 m
What is the structure of an atom?
A positively charged nucleus containing protons and neutrons surrounded with negatively charged electrons
Where is most of the mass of an atom?
In the nucleus
Where are electrons?
Arranged at different distances from the nucleus. Energy levels
What is an atom?
It has the same number of protons and neutrons with an overall neutral charge
What is an isotope?
An atom of the same element with different numbers of neutrons. They have a different mass
How is an ion formed?
Atoms turn into positive ions if they lose one or more of their outer electrons
Why do scientists look for new evidence about atoms?
New evidence may lead to a scientific model being updated or changed
Explain the plum pudding model
A positively charged ball embedded with negatively charged electrons
Who created the plum pudding model?
JJ Thompson
What did Rutherford’s alpha particle experiment prove?
The mass of an atom is concentrated in a central nucleus which is very small and dense
What did Bohr change about the nucleus model?
He added energy levels for electrons
Who discovered the neutron?
Chadwick
What is radioactive decay?
If a nucleus is unstable it will give out radiation to become stable
What is an alpha particle?
A helium nucleus. It has 2 neutrons and 2 protons. Overall charge of 2+
What is a beta particle?
An electron released from the nucleus as a neutron turns into a proton. Overall charge of 1-
What is a gamma ray?
Electromagnetic radiation from the nucleus
What is the ionisation of an alpha particle?
High
What is the range in air of an alpha particle?
A few centimeters
What can stop an alpha particle?
A sheet of paper
What is the ionisation of a beta particle?
Medium
What is the range in air of a beta particle?
A few meters
What can stop a beta particle?
A few mm of aluminium
What is the ionisation of a gamma wave?
Low
