# Structure of Atom

## Electronic Configuration

The maximum number of electrons can be obtained by 2n2; where ‘n’is the orbit number. Thus after knowing the maximum number of electrons for a particular shell, the arrangement of electrons in an atom can be identified. It is called Bohr Bury Schemes.

## Rules to write the electronic configuration of an atom

1. Maximum number of electrons in an orbit is calculated by 2n2, where ‘n’ is number of orbit and may be equal to 1, 2, 3 , . . . .
2. Electrons occupy the next orbit only after filling the inner orbit completely.
3. The maximum number of electrons in outermost orbit will not be more than 8.

### Electronic configuration of Hydrogen

Atomic number of hydrogen = 1

Therefore number of electrons = 1

Maximum number of electrons in 1st orbit = 2

Since, hydrogen has only one electron, therefore, it will reside in 1st orbit.

Thus electronic configuration of hydrogen

Number of orbit present in hydrogen = 1

### Electronic configuration of Helium

Atomic number of helium = 2

Therefore number of electrons = 2

Therefore, electronic configuration of helium is

Number of orbit in helium atom = 1

### Electronic configuration of Lithium

Atomic number of Lithium = 3

Therefore number of electrons = 3

Since the maximum number of electrons in 1st orbit is equal to 2, therefore, after accommodating 2 electrons in 1st orbit, the third electron will go in 2nd orbit.

Thus, electronic configuration of lithium is

Number of orbit in Lithium atom = 3.

### Electronic configuration of Beryllium

Atomic number of beryllium = 4.

Therefore number of electrons = 4.

Thus, electronic configuration of Beryllium is

Number of orbit in beryllium = 2

### Electronic configuration of Boron

Atomic number of boron = 5

Therefore number of electrons = 5

Thus, electronic configuration of boron is

Number of orbit in boron = 2

### Electronic configuration of Carbon

Atomic number of carbon = 6

Therefore number of electrons = 6

Thus, electronic configuration of carbon is

Number of orbit in carbon = 2