Electron shells

Question	Answer
Electron shell rules	1) electrons always occupy shells (sometimes called energy levels) 2) the lowest energy levels are always filled first 3) only a certain number of electrons are allowed in each shell (2 electrons in the 1st shell, 8 in the 2nd and 8 in the 3rd)
Electron configurations	Image: 7-N-nitrogen-electron (image/png)
Electronic configuration	You can use the electronic configuration to work out the period, group and atomic number of an element: the period of the element is the same as the number of shells which contain electrons, the group number can be found by looking at how many electrons occupy the outer shell of the element (e.g) sodium has the elecronic configuration 2,8,1. The period number is 3 as there are 3 shells occupied. The group number is one as there is one electron in the outer shell. the atomic number is found by adding up all the electrons. You can use it to identify elements

Resource summary

	Created by eibhlinjones200 over 11 years ago