An ion is a positively or negatively charged atom or group of atoms. For example sodium ion, magnesium ion, chloride ion, sulphate ion, etc, There are two types of ions. A positively charged ion is known as cation, It is formed by the loss of one or more electrons by an atom. An anion is a negatively charged ion. It is formed by the gain of one or more electrons by the atom.

Which of the following is a nonmetal? A 11 23 and B 17 19

B 17 19 is a nonmetal. The subscript indicates the atomic number and superscript mass number. Atomic number = number of protons = number of electrons. The electronic configuration for this element B is as given below. K shell = 2, L shell = 8, and M shell = 7. Hence, to attain a stable inert gas configuration (octet) it gains one electron in a chemical reaction. Nonmetals are electron acceptors.