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The short-hand notation of a very large or very small number expressed in power 10 is called exponential Notation. The mass of electron is 0.000 000 000 000 000 000 000 000 000 911g, this can be written by exponential notation as 9.11x10 -28 g. The number of atoms present in 1mole of elements is found to be 602,300,000,000,000,000,000,000 which can be written as 6.023x10 23 . In Exponential terms, 10 is called the base. The power to base is called exponent or logarithm. There are two methods of determining the exponents of 10. 1) When decimal point shifted towards right side, the exponent of 10 is always negative in such a case. Example: 0.00016 can be expressed as 1.6x10 -4 . 2) When decimal point shifted toward left side, the exponent of 10 is always positive in such a case. Example: 16000 can be expressed as 1.6x10 4 .   In the expression, a x =y is called the logarithm of y to the base a, where a must be positive number other than one. In logarithm the base is us...

"An ionic bond is the force of attraction between oppositely charged ions in a compound."         This type of Chemical bond was proposed by Kossel (1916). Electrovalent bond is formed by transference of one or more electrons from the outermost shell of one atom to the valence shell of other. The atom losing electron becomes positive ion due to having more proton (having +ve charge) in the nucleus than electrons in shell. The atom which gains the electrons becomes –ve ion. Consequently, both the atoms acquire inert gas configuration.       Consider formation of NaCl from sodium and chlorine atoms. Sodium atom has one electron in the outermost shell, while Chlorine has seven electrons in its valence shell. When these two atoms come close each other, one electron from sodium is transferred to Chlorine atom.            The positive sodium ion Na + and the negative chloride ion Cl - ...