Atom Size
Chemistry: AQA GCSE Higher, topic 1.1.10
Atoms and Sub-Atomic Particles
Atoms are tiny and very light. They are made up of sub-atomic particles (protons, neutrons, and electrons), which are even smaller and lighter than an atom.
How big are atoms?
- The radius of atoms is approximately 0.1 nanometres, or 1x10-10 m.
- About 5 million hydrogen atoms could fit into a pinhead.
- The nucleus of an atom is 10,000 times smaller than the atom.
- If an atom was the size of Wembley Stadium, then the nucleus would be the size of a garden pea.
Relative mass
- Sub-atomic particles:
- Relative mass of protons and neutrons = 1
- Relative mass of electrons = 0.0005 (this gets rounded to zero)
- Atoms:
- Relative mass = number of protons + number of neutrons
Test yourself on Atom Size
What is the relative mass of an electron?
What is the average radius of atoms?
Which sub-atomic particle does NOT have a relative mass of 1?
In what environment would the relative mass of an atom change?
Two atoms have the same number of protons, but one has more neutrons than the other. What is true of their relative masses?