The building blocks of all matter are called atoms .An atom is the smallest characteristic particle of a given element. Atoms are very small and atomic radius is measured in nanometres. Maharishi Kanad and Pakudha Katyayana (Indian philosophers) studied about the particles of matter. The smallest particles of matter were named "Parmanu" by Maharishi Kanad. Democritus (Greek philosopher) called indivisible particles atoms.
The concept of formation of compounds was first given by Antonis L. Lavosier and Joseph L. Proust who gave the laws of chemical combination.
An atom of an element is known with the same symbol and name as of it's element. International Union of Pure and Applied Chemistry (IUPAC) approves names of elements, symbols and units. The first letter of a symbol is always written as a capital letter and the second letter as a small letter.
Atomic Mass Unit:--
One atomic Mass Unit is a mass unit equal to exactly one twelfth (1\12th) the mass of one atom of carbon- 12.
The latest short form of atomic Mass Unit is 'u' according to IUPAC.
Relative Atomic Mass Unit:--
Relative Atomic Mass Unit of an element is defined as the average mass of the atom,as compared to 1\12th the mass of one carbon-12 atom.
Q. a) When 3g of magnesium is burnt in 2g of oxygen,5g of magnesium oxide is produced.What mass of magnesium oxide will be formed when 3g of oxygen is burnt in 5g of oxygen? b) Which law of chemical combination will govern your answer?Ans: a) when 3g of magnesium is burnt in 2g of oxygen,5g of magnesium oxide is produced.Thus magnesium and oxygen combine in the 3:2 ratio.Hence when 3g of magnesium is burnt in 5g of oxygen, 5g of magnes... read more