Definitions [4]
The atomic number of an element is equal to the number of protons in the nucleus.
Atomic number (Z) = Number of protons.
= Number of electrons.
The mass number of an element is the sum of the number of protons and neutrons in the nucleus of the atom of that element.
Mass number (A) = No. of protons (p)
+ No. of neutrons (n)
The atoms of the same element, having same atomic number Z, but different mass number A, are called isotopes.
OR
Atoms having the same atomic number (Z) but different mass numbers (A).
Define the term Electronic configuration.
Electronic configuration of an atom is defined as the distribution of its electrons in orbitals.
Theorems and Laws [1]
The ground state energy of the hydrogen atom is -13.6 eV. The kinetic and potential energy of the electron in the second excited state is respectively ______
The ground state energy of the hydrogen atom is -13.6 eV. The kinetic and potential energy of the electron in the second excited state is respectively 1.51 eV, -3.02 eV.
Explanation:
For second excited state n = 3
The total energy in the third orbit
`E_3 = (-13.6)/9`eV = -1.51 eV
K.E. = -T.E. = 1.51 eV
P.E. = 2.T.E. = -3.32 eV
