The average atomic mass of a sample of an element X is 16.2 u, what are the percentages of isotopes `"_8^16X` and `"_8^18X` in the sample?

The atomic number of an element X is 16. (b) What will be the valency of X ?

The atomic number of an element X is 16. (a) Write down the electronic configuration of X.

The electronic configuration of an element Z is 2, 8, 8. (a) What is the atomic number of the element ?

What is the reason for the different atomic masses of the isotopes of an element ?

The atomic number of an element X is 8 and that of element Y is 4. Both these elements can exhibit a valency of :

The atomic mass of an element is the weighted average of the atomic masses of different isotopes of that element .This explains,why atomic masses of many elements show large departures from integer values.However ,even if we consider msases of individual isotpes,they are not strictly integer multiples of the mass of a hydroen atom.How do yo account for this fact?

In a periodic table the average atomic mass of magnesium is given as 24.312 u. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are "_12^24Mg (23.98504u), "_12^25Mg (24.98584u) and "_12^26Mg (25.98259u). The natural abundance of "_12^24Mg is 78.99% by mass. Calculate the abundances of other two isotopes.

The number of electrons in the atom of an element X is 15 and the number of neutrons is 16. Give representation of an atom of this element ?