Atoms, Moles, Formulae and Equations

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Atom is the smallest particle of an element, which can take part in chemical reaction. Molecule is the smallest particle of an element which can exist on its own and still retain the chemical properties of that element.  Ion is an atom or group of atoms which are either positively or negatively charged due to loss or gain of electrons. First 20 elements Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Flourine Neon Sodium Magnesium Aluminum Silicon Phosphorus Sulphur Chlorine Argon Potassium Calcium Relative atomic mass of an element is the number of times the average mass of one atom of an element is greater than one twelfth of the mass of carbon 12. Relative Molecular mass of a compound is the number of times the average mass of one Molecule of the substance is greater than one-twelfth of the mass of carbon 12. Mole One mole of a substance is the amount containing as many elementary entities as the number of atoms in exactly 12 grams of carbon 12.  Note: Avogadro
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What is Matter

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Matter

Matter is anything that has weight and/or mass and occupies space. examples are stone, plants.

States of Matter

Matter exists in three physical states like solid, liquid and gas.
Solid- it has a definite shape and volume
Liquid-it has no definite shape but occupies the volume of the containing vessel.
Gas- it has no definite shape but occupies the whole volume of the containing vessel.

Properties of Matter
 Matter possesses both physical and chemical properties. physical property is associated with physical changes while chemical property is associated with chemical changes. Physical change is one that is easily reversible and no new substance is formed e.g melting of candle wax. Chemical change is one that is not easily reversible and new substance is formed. Eg rusting of iron.

Difference between chemical and physical changes
Chemical
1. New substance is formed
2. Heat is evolved
3. It is not easily reversible
4. Change in mass
Physical
1. No new substance is formed
2. No heat is evolved
3. It is easily reversible
4. No change in mass
Please compare the differences above.

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