Key Points

Metals are generally lustrous (shiny), malleable (can be beaten into sheets), ductile (can be drawn into wires), and are good conductors of heat and electricity. They are typically solid at room temperature, except for mercury.

Non-metals are generally non-lustrous, brittle, not malleable or ductile, and are poor conductors of heat and electricity. They can exist as solids, liquids (bromine), or gases at room temperature.

Key exceptions include mercury (liquid metal), alkali metals (soft), iodine (lustrous non-metal), and carbon allotropes like diamond (hardest natural substance) and graphite (conducts electricity). Gallium and caesium melt on the palm.

Most metals react with oxygen to form metal oxides, which are generally basic in nature. For example, when copper is heated, it forms a black layer of copper(II) oxide: $2Cu(s) + O_2(g) \rightarrow 2CuO(s)$.

Some metal oxides, such as aluminium oxide ($Al_2O_3$) and zinc oxide ($ZnO$), exhibit both acidic and basic behavior. They react with both acids and bases to produce salts and water.

The reactivity series is a list of metals arranged in order of their decreasing reactivity. A more reactive metal can displace a less reactive metal from its salt solution, which is the basis for displacement reactions.

Metals that are more reactive than hydrogen will displace hydrogen from dilute acids to form a salt and hydrogen gas. For example, $Mg(s) + 2HCl(aq) \rightarrow MgCl_2(aq) + H_2(g)$.

Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid (HCl) and concentrated nitric acid ($HNO_3$) in a 3:1 ratio. It is a highly corrosive liquid capable of dissolving noble metals like gold and platinum.

Ionic compounds are formed by the complete transfer of electrons from a metal to a non-metal. The metal forms a positively charged ion (cation) and the non-metal forms a negatively charged ion (anion).

Ionic compounds are hard, brittle solids with high melting and boiling points due to strong inter-ionic attraction. They are typically soluble in water and conduct electricity only in molten state or in aqueous solution.

Minerals are naturally occurring compounds of elements. Ores are minerals from which metals can be extracted profitably. The impurities such as soil and sand found in ores are called gangue.

Highly reactive metals (K, Na, Al) are extracted by electrolysis. Moderately reactive metals (Zn, Fe, Pb) are extracted by reduction of their oxides with carbon. Low reactivity metals (Ag, Au, Hg) are often found in their native state or extracted by heating alone.

Roasting is the process of heating sulphide ores in the presence of excess air to convert them into oxides. Calcination is the process of heating carbonate ores in limited or no air to convert them into oxides.

The reaction between iron(III) oxide ($Fe_2O_3$) and aluminium (Al) is a highly exothermic displacement reaction used for welding railway tracks. The equation is $Fe_2O_3(s) + 2Al(s) \rightarrow 2Fe(l) + Al_2O_3(s) + \text{Heat}$.

In electrolytic refining, the impure metal is made the anode, a thin strip of pure metal is the cathode, and a salt solution of the metal is the electrolyte. Pure metal from the anode dissolves and deposits onto the cathode.

Corrosion is the process where metals are damaged by reaction with substances like air and moisture, such as the rusting of iron. It can be prevented by painting, oiling, galvanising (coating with zinc), chrome plating, or making alloys.

An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal, designed to have improved properties. For example, stainless steel (an alloy of iron, nickel, and chromium) is hard and resistant to rust.