Metals are
lustrous, malleable, ductile and are good conductors of heat and electricity.
The non-metals are
either solids or gases except bromine which is a liquid.
All metals except
mercury exist as solids at room temperature.
Carbon is a
non-metal that can exist in different forms. Each form is called an allotrope.
Such metal oxides
which react with both acids as well as bases to produce salts and water are
known as amphoteric oxides.
Anodising is a
process of forming a thick oxide layer of aluminium.
Aqua
regia, (Latin for ‘royal water’) is a freshly prepared mixture of
concentrated hydrochloric acid and concentrated nitric acid in the ratio of
3:1. It can dissolve gold, even though neither of these acids can do so alone.
is one of the few reagents that is able to dissolve gold and platinum.
The compounds
formed in this manner by the transfer of electrons from a metal to a non-metal
are known as ionic compounds or electrovalent compounds.
the ores of many
metals are oxides. This is because oxygen is a very reactive element and is
very abundant on the earth.
The extraction of
metals from their ores and then refining them for use is known as metallurgy.
Ores mined from the
earth are usually contaminated with large amounts of impurities such as soil,
sand, etc., called gangue.
cinnabar (HgS) is
an ore of mercury.
copper which is
found as Cu2S in nature
Silver articles
become black after some time when exposed to air. This is because it reacts
with sulphur in the air to form a coating of silver sulphide.
Galvanisation is a
method of protecting steel and iron from rusting by coating them with a thin
layer of zinc.
The electrical
conductivity and melting point of an alloy is less than that of pure metals.
An alloy is a
homogeneous mixture of two or more metals, or a metal and a non-metal.
All non-metals are
not good conductors of electricity, except Graphite.
Next Topic:-Science Class 10 NCERT Textbook- Lesson-4
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