Teaching model
Review page: Brief summary
The picture shows an image of atoms of the metal nickel generated using scanning tunnelling microscopy.
Scientists in the early 1900's showed that atoms are composed of particles having the properties given in the table.
| particle name | actual mass /g | mass /atomic mass units | actual charge /C | charge chemists use |
| proton (p+) | ~10–24 | 1 | +1.6×10–19 | +1 |
| neutron (n0) | ~10–24 | 1 | 0 | 0 |
| electron (e–) | ~10–28 | 0 | –1.6×10–19 | –1 |
The charge on the electron is the fundamental unit of charge. It is more convenient to express other charges relative to it (thus +1 or -1) than to quote the actual charge.
Similarly, relative masses are used for the proton, neutron and electron.
Similarly, relative masses are used for the proton, neutron and electron.
The nucleus contains both protons and neutrons and contains most of the mass of the atom. These particles are known as nucleons. The nucleus has a positive charge.
The electrons are in constant motion about the nucleus. The electron cloud shows the region in which the electrons are likely to be found. The nucleus is very very small in comparison to the electron cloud.
Move your mouse over the electron cloud to see a much expanded view of the nucleus.
The electrons are in constant motion about the nucleus. The electron cloud shows the region in which the electrons are likely to be found. The nucleus is very very small in comparison to the electron cloud.
Move your mouse over the electron cloud to see a much expanded view of the nucleus.