Properties of metals

Metals are usually solid (except mercury), lustrous, malleable and good conductors of heat and electricity. These properties are explained by the metallic bond: positive ions (and atoms) sit at the lattice sites and the valence electrons move freely through the whole crystal. Silver and copper are the best conductors and gold is the most malleable metal; mercury melts at –39 °C and tungsten at about 3410 °C; chromium is the hardest metal and sodium and potassium are the softest. In reactions metal atoms give up valence electrons and are oxidised, i.e. they act as reducing agents: M – ne⁻ → Mⁿ⁺. The electrochemical series, in order of decreasing activity, is Li, K, Ba, Ca, Na, Mg, Al, Mn, Zn, Cr, Fe, Ni, Sn, Pb, (H), Cu, Hg, Ag, Pt, Au. Each metal displaces those after it from solutions of their salts (Fe + CuSO₄ → FeSO₄ + Cu); metals before hydrogen displace hydrogen from dilute acids (Zn + 2HCl → ZnCl₂ + H₂↑) while those after hydrogen do not. The most active (alkali) metals react with the water of the solution first. Experiments with acids are done by the teacher only.