Metals and Non-metals
* Metals are elements that have a tendency to lose electrons and form positively charged ions or cations.
* Elements that have a tendency to accept electrons to form negatively charged ions or anions are called non-metals.
* Metals are placed on the extreme left in the periodic table, while non-metals are placed on the extreme right in the periodic table.
* Metals are solids, malleable, ductile, lustrous with high milting and boiling points.
* Metals are electropositive, good conductors of heat and electricity, form basic oxides which are ionic.
* Non-metals exist as solids, liquids and gases, non malleable, non ductile, non-lustrous with low melting and boiling points.
* Non-metals are electronegative, bad conductors of heat and electricity, form acidic oxides which are covalent.
* Electrolysis is a process of decomposition of an ionic compound by passing electricity through it.
Activity Series
* The Activity Series of metals refers to the arrangement of metals in decreasing order of their reactivity.
* Reduction is the process in which metal oxides get reduced to metals by reducing agents like carbon, hydrogen, carbon monoxide, etc.
* Metals at the bottom of the activity series are not reactive and can be extracted by reduction.
* Metals at the top of the active series are highly reactive and can be extracted through electrolysis.
The important ores of aluminium are:
* Bauxite
* Corundum
* Cryolite
The extraction of aluminium involves three steps:
* Purification of bauxite by Bayer’s process.
* Electrolytic reduction of anhydrous alumina by Hall and Herault’s process.
* Purification of impure aluminium by Hoope’s process.
* Aluminium is used in the manufacture of automobile components, electric wires, and in the construction process.
The two important alloys of aluminium are:
* Duralumin
* Magnalium
* Duralumin is used in the making of aircraft parts and pressure cookers.
* Magnalium is used in the making of machined articles and cheap physical balances.