Physical and chemical property differences between metals and non-metals:
Metal atoms have larger atomic size so their valence electrons are held less tightly by the nucleus. This allows the valence electrons to move freely making metals good conductors of heat and electricity. Metals have 1, 2 or 3 valence electrons and tend to lose one or more electrons when supplied with energy and form cations. Thus, they are electropositive in nature and strong reducing agents.
Non-metal atoms have relatively smaller atomic size. So, their valence electrons are held tightly by the nucleus, they are not free to move. This makes non-metals bad conductors of heat and electricity. Non-metals have 5, 6 or 7 electrons in the valence shells and tend to gain electrons to form anions. Thus, non-metals are electronegative in nature and strong oxidizing agents.
Definition of Metal:
A Metal is an element which ionizes by losing electrons when energy is supplied to it and is hence an electron donor. Metals have 1, 2 or 3 valence electrons (positive valency of 1, 2 or 3) and tend to form positive ions (cations) on ionization. Thus, Metals form electrovalent compounds. Metals form at least one basic oxide. For example — K2O, Na2O, CaO, MgO, CuO, etc.
Position [group] in the periodic table:
(i) Na — alkali metal — Group I (IA)
(ii) Mg — alkaline earth metal — Group 2 (IIA)
(iii) Fe and Zn transition elements — Group 8 (VIII), Group 12 (IIB)
(iv) Inner transition elements — Group 3(IIIB) but are shown separately as f-block of the periodic table.
(v) Al — post transition element — Group 13 (III A)
