9th science

Structure of The Atom

Arrangement of electrons in an 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

• 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 , . . . .
• Electrons occupy the next orbit only after filling the inner orbit completely.
• 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

Thomson Model

Bohr Model

Atomic Number

Electronic Configuration

Elec Config N to Mg

Elec Config Al to Ca

Valency

In Text Solution

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