The Role of Electrons
By Abbey Abdul
An electron shell, also called a principle energy level may be thought of as an orbit followed by electrons around atom's nucleus. The closest shell to the nucleus is called the "1 shell" also called "K shell", followed by the "2 shell" or "L shell", then the "3 shell" or "M shell", and so on farther and farther from the nucleus.
Ions are molecules or atoms which the number of protons are not equal to the number of electrons. They form in chemical reaction because the electrons move from atom to atom. If an Ion loses one or more electrons, it becomes positive and is known as a cation. If it gains electrons, it becomes negative and is known as an anion.
The electrons configuration for the first 18 elements show that:
1. The number of occupied shells in a atom is the same as the period element.
2. For groups I and II the group number is the same as the number of outer shell electrons.
3. For group III to VIII the number of group is the same as the number of outer shell electrons.
Valence electrons are electrons in the last shell of an atom. They show a periodic pattern. The valence electrons increases in number as you go across a period. When a new period starts, the number drops back down to one and starts increasing again.