The model of the atom consistent with experiment has a very small nucleus containing the protons and neutrons at the center of an electron cloud.
Tap the image to see an expanded view of the nucleus.
The chemical properties of an element can be understood in terms of the arrangement of the electrons in the electron cloud.
Tap the image to see an expanded view of the nucleus.
The chemical properties of an element can be understood in terms of the arrangement of the electrons in the electron cloud.
The model of electron arrangement consistent with experimental data has electrons in specific (discrete) energy levels (shells).
Electron shell 1 is closer to the nucleus. This model is quite different from to an alternative model, also shown, where electrons may have any energy.
The energy of the electron shells increases with distance from the nucleus. In the ground (normal) state of the atom, the electrons occupy the lowest energy levels (shells) possible.
Up to four energy levels (shells) are occupied by electrons on the first twenty elements in the periodic table.
- the number of shells occupied
- the number of electrons in each shell