A physical property is any property that is measurable whose value describes a state of a physical system.A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.Isotopes are variants of a particular chemical element which differ in neutron number, although all isotopes of a given element have the same number of protons in each atom.The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number (number of protons), electron configurations, and recurring chemical properties. A period is the name given to a horizontal row of the periodic table.a group is a column of elements in the periodic table of the chemical elements.