Page 47 - ICSE Chemistry 6

Molecule: A group of two or more atoms of the same element or diff erent elements held together
by chemical forces which is capable of independent existence
Noble (inert) gases: Non-metals that are present in gaseous state and do not react chemically with other
elements
Metalloids: Elements that possess the proper es of both metals and non-metals
Compound: A pure substance formed by the chemical combina on of two or more elements in a
defi nite propor on by mass

Mixtures: Physical combina on of two or more elements or compounds in any propor on
Sieving: A method used to separate components of a mixture that diff er in size
Sedimenta on: The process of se ling down of suspended insoluble par cles at the bo om under the
infl uence of gravity
Sediment: The insoluble solid substance that se les down

Decanta on: Pouring of clear liquid into another beaker without disturbing the sediment
Supernatant liquid: The clear liquid over the sediment
Residue: The insoluble solid le behind on the fi lter paper
Filtra on: A method used to separate an insoluble solid and a liquid

Filtrate: The clear liquid that passes through the fi lter paper
Evapora on: A process by which a liquid is converted into its vapour state
Magne c separa on: A method used to separate components of a mixture containing a magne c substance
Sublima on: The process by which a solid changes into vapour directly without going into liquid
state on hea ng

Quick Review

• Ma er is composed of certain basic substances called elements, each of which is itself composed of
minute par cles of its own kind called atoms.
• Some atoms are capable of independent existence while others are found in combina on with atoms
of the same element or diff erent elements.
• Elements are classifi ed on the basis of their proper es into metals, non-metals, metalloids and noble
gases.
• A majority of elements are metals. Metals are mostly found in the earth’s crust, but they are also
found in seas and oceans.
• Non-metals are found in abundance in nature.
• Non-metals like helium, neon, argon, krypton, xenon and radon are noble gases.
• Boron, silicon, arsenic and an mony are some metalloids.
• When elements combine with each other in a fi xed ra o by mass, they form compounds.
• The smallest unit of a compound is a molecule which shows all the proper es of the compound.
• To represent an element, some abbrevia ons called symbols are used. A symbol represents one atom
of an element.
• A molecule is the smallest par cle of an element or a compound that exists independently and shows
all the proper es of that substance.
• Elements and compounds have diff erent uses based on their proper es.

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