Electronic configuration
we can represent the the structure of atoms in two ways ; using diagrams called electron shell diagrams or by writing out special notation called electronic configuration .
Electron shell diagram
Electron orbit the nucleus in shells ( or energy levels )and each shell has different energy amount associated with it
The further away from the nucleus , the more the shell has
electron fill the shell closest to the nucleus
when the shell become full of electrons , additional electrons have to be added to the next shell
the first shell can hold two electrons
the second shell can hold 8 electrons
the outermost shell is called valence shell , and an atom is more stable if it can manage to completely fill this shell with electrons
the arrangement of electron in shell can also be explained using numbers
Ex - carbon has 6 electrons , 2 in the first shell and 4 in the second shell
its electronic configuration is 2,4
electronic configuration can also be written for ions
Ex - sodium atom has 11 electrons , a sodium ion has lost one electron , therefore has 10 electrons
2 in the first shell and 8 in the second shell
its electronic configuration is 2,8
the electronic configuration of first 20 elements
