How are electrons distributed within the electron shells of an atom?

Answer 1

An electron shell may be crudely thought of as an orbit followed by electrons around an atom's nucleus. It must be emphasised that this crude model has been superseded by quantum theory in specifying the electron behaviour. However it did give an understanding of how the atoms of the Periodic Table are configured. The electron shells are labelled K, L, M, N,O,P, and Q, moving outwards from the nucleus. Each shell is composed of subshells labelled s,p,d, and f. The K shell has one subshell, the s. The L shell has two subshells, s and p. the M shell has three subshells s,p, and d. The N shell has four subshells, s,p,d, and f.

Further rules apply: each s subshell can hold up to two electrons, each p subshell up to six, each d subshell up to ten, and each f subshell up to fourteen.

Thus the overall effect is: K shell can contain up to two electrons, L shell up to eight, M shell up to eighteen, and N shell up to thirty two. Subsequent shells can hold up to thirty two, no known element has more than 32 electrons in any one shell.

This model of the atom is generally called the Bohr model after the physicist ,who developed the model in the 1920's.

The reasons for this electron configuration are beyond this answer, but there are articles in Wikipedia if you want to try to understand this. See 'Electron Configuration' for example and also follow other links given.

Answer 2

Atoms combine with other atoms by forming links called bonds. Chemical bonds result from interactions of electrons.

The electrons of an atom occupy one or more regions of space called electron shells that encircle the nucleus. Because electrons have a leel of energy characteristics of the particluar shell they are in, the shells are sometimes called energy shells. Each elecron shell can hold a limited number of electrons. The maximum number of electrons that each of the first three shells can hold for elements of atomic number 18 and under is

First shell (closest to the nucleus) 2 electrons

Second shell 8 electrons

Third shell 8 electrons

More complex atoms may have as many as eighteen electrons in the third shell.

Answer 3

Electrons are arranged in main energy levels and then into sublevels depending on the atom.

In summary:

The main energy levels are given a number, the sublevels are given a letter. Each sublevel contains orbitals that can hold upto 2 electrons ie 0, 1 or 2 electrons.

For elements other than hydrogen the arrangement of sublevels is as follows from the nucleus:

1s, - one s orbital ie maximum of 2 electrons. Helium has this level filled.

2s & 2p - one s and three p orbitals ie maximum of 8 electrons. Neon has this level filled.

3s & 3p - one s and three p orbitals ie maximum of 8 electrons. Argon has this level filled.

4s, 3d, 4p - one s, five d and three p orbitals ie maximum of 18 electrons. Krypton has this level filled.

(Complicated isn't it ;-)

5s, 4d, 5p - Xenon. and if we keep going the next level looks like this

6s, 5d, 6p, 4f - seven f orbitals ie upto 32 electrons. Radon has this level filled.

The sublevels of lower energy levels are 'promoted' to a higher energy level. They have enough energy to sit in the next energy level.

Hydrogen does not promote orbitals to a higher energy level so the energy levels are more straight forward.

Answer 4

by quantum jumps when photons are absorbed and/or emitted.

Answer 5

The simple answer is that two electrons will fit into the first (innermost) shell while the rest of the shells can take upto eight.