Friday, January 6, 2012

TET/CTET Science study notes for paper-II

TET/CTET Science study notes for paper-II

Metals are solids at room temperature with the exception of mercury and gallium, which are liquids at room temperature. Gallium and Caesium melt below 30c . So if room temperature is around 30c, they may also be in liquid state
Metals are hard but not brittle, except zinc at room temperature.
Metals, in their pure state, have a shining surface. This property is called metallic luster e.g., gold, silver and copper

Metals can be beaten into thin sheets known as foils. This property is called malleability. Gold and silver are the most malleable metals.

The ability of metals to be drawn into thin wires (except sodium, potassium, calcium, lead etc.)is called ductility. Gold is the most ductile metal. It is because of their malleability and ductility that metals can be given different shapes according to our needs like for making cooking vessels or making jewellery.
Metals are generally hard except sodium and potassium, which are soft and can be cut with a knife.
When metals strike a hard surface produce a sound and are said to be sonorous like iron or aluminum
Metals have high melting points but gallium and caesium have very low melting points.
Metals have 1 to 3 electrons in the outermost shell of their atoms. The greater the number of shells and lesser the number of valence electrons, the greater is the reactivity of the metal.
Metals are good conductors as they have free mobile electrons. Silver and copper are the two best conductors of heat and electricity. Lead is the poorest conductor of heat. Bismuth, mercury and iron are also poor conductors.
Metals have high density and are very heavy except sodium, potassium, calcium etc. Iridium and osmium have the highest densities where as lithium has the lowest density.
Metals have high melting and boiling point except mercury, cesium, gallium, tin, lead. Tungsten has the highest melting point where as silver has low boiling point. Sodium and potassium have low melting points.
Metals always ionize by losing electrons and become positively charged ion or Cation
 Na - 1e- à Na+

Metals are always deposited at the cathode during electrolysis.
Metals lose electrons and hence get oxidized. Hence They are reducing agents.
Metals generally form basic oxides, some of which are also amphoteric, such as aluminium oxide, zinc oxide, lead oxide etc.
Metals usually do not form hydrides by reacting with hydrogen except those of sodium, potassium and calcium.
Metal react with chlorine and produce chlorides, which are electrovalent.
Metals on reaction with dilute acids they give respective salt and hydrogen.


Properties of Non-metalsNon-metals exist in two of the three states of matter at room temperature: gases (oxygen) and solids (carbon). These have no metallic lustre, and do not reflect light.
Non-metals are not lustrous, except iodine and diamond which is the most lustrous of all the substances
Non-metals are usually not hard exception is diamond which is the hardest substance.
Non-metals are very brittle, and cannot be rolled into wires or pounded into sheets.
Non-metals are poor conductors of heat and electricity except for carbon in the form of graphite and the gas carbon
Non-metals have a tendency to gain or share electrons with other atoms. They are electronegative in character. By gaining electron form anions
Non-metals generally form acidic or neutral oxides with oxygen.
Non-metals have 4, 5, 6 or 7 electrons in the valence shell. If it has 8 electrons, it is called a noble gas. Lesser the number of shells and greater the number of valence electrons, greater is the reactivity of the non-metal.
Non-metals gain electrons to form anions and hence get reduced and act as a oxidizing agents.
Non-metal gain or share electron so exhibit both electrovalency or covalency.
Non-metals are always deposited at the anode during electrolysis.
Non-metals generally form acidic oxides when react with oxygen. Some oxides are neutral, such as nitrous oxide, nitric oxide, carbon monoxide water etc
Non-metals produce chlorides, which are covalent when, react with chlorine

Non-metals  form hydrides when react with hydrogen , e.g. NH3, PH3, HCl,  HBr, HI, H2S, H2O etc.

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