Atomic structure: sub-atomic particles
Atoms are made of smaller sub-atomic particles called protons, neutrons and electrons.
An atom has a central part called the nucleus. Inside the nucleus, there are protons and neutrons.
The electrons orbit the nucleus on electron shells, also known as energy levels.
The three sub-atomic particles have a different relative charge and relative mass, summarised in the table below:
In any individual atom,
the number of protons is equal to the number of electrons, so atoms are neutral overall,
this means the atoms have not got an overall electrical charge
(positive charges are cancelled out by an equal number of negative charges).
An atom that contains 3 protons and 3 electrons, has a neutral overall charge.
Q1. What sub-atomic particles are found in the nucleus of an atom?
Neutrons and protons
Q2. What sub-atomic particles are found on the electron shells?
electrons
Q3. What is the charge of a proton?
Positive (1+)
Q4. What is the charge of a neutron?
Neutral (zero)
Q5. Where are the protons and neutrons found?
In the nucleus
Q6. What is the charge of an electron?
Negative (1-)
Q7. What is the overall charge of a nucleus?
Positive
Q8. What is the mass of a proton?
1
Q9. What is the mass of a neutron?
1
Q10. What is the mass of an electron?
Almost zero (or 1 / 2000) (or 0.0005).
Q11. What two types of subatomic particle have the same mass?
Proton and neutron
Q12. Which sub-atomic particle has the lowest mass?
Electron
Q13. Which particle has no electrical charge?
Neutron
Q14. What is the overall charge of an atom? Why?
An atom is neutral overall.
Because there is an equal number of positively charged protons and negatively charged electrons, and their charges cancel out.
Q15. The figure below represents an atom of an element.
Name the parts of the atom labelled A, B, C and D.
A - electron
B - neutron
C - electron shell or energy level
D - proton
Q16. The figure below represents an atom of element Z.
Name the parts of the atom labelled A and B.
A - nucleus
B - electron
Q17. The table below shows properties of two subatomic particles.
Complete the table.
Neutron: Mass of 1, Charge zero (0)
Proton: Mass of 1, Charge + 1
Q18. Complete the sentences.
The centre of the atom is the ___________________ .
The two types of particle in the centre of the atom are the proton and the ______________ .
The two types of particle with the same mass are the neutron and the ________________ .
The centre of the atom is the nucleus.
The two types of particle in the centre of the atom are the proton and the neutron.
The two types of particle with the same mass are the neutron and the proton.
Q19. The figure below shows a lithium atom.
What is the number of electrons and neutrons in the atom of lithium?
Electrons: 3
Neutrons: 4
Q20. The figure below shows a beryllium atom.
What is the number of electrons and neutrons in the atom of beryllium?
Electrons: 4
Neutrons: 5
Q21. The figure below shows a carbon atom.
Describe the atomic structure of this carbon atom.
You should include the number of electrons, neutrons and protons. (6)
6 protons in nucleus
8 neutrons in nucleus
6 electrons around nucleus in energy levels / shells