In the periodic table, the elements are listed in order of increasing atomic number Z. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. The configuration of these electrons follows from the principles of quantum mechanics.

The chemical properties of the atom are determined by the number of protons, in fact, by number and arrangement of electrons. There is a recurring pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties. Generally, within one row (period) the elements are metals to the left, and non-metals to the right, with the elements having similar chemical behaviours placed in the same column.Įvery solid, liquid, gas, and plasma is composed of neutral or ionized atoms. It is organized in order of increasing atomic number. The periodic table is a tabular arrangement of the chemical elements.

Period 4 elements