Request a call back

# Atomic Structure

Atomic Structure PDF Notes, Important Questions And Synopsis

## Atomic Structure PDF Notes, Important Questions and Synopsis

SYNOPSIS

Dalton’s atomic theory:
Dalton’s atomic theory is based on the law of conservation of mass and the law of definite proportions. He also proposed the law of multiple proportions.

Thomson’s model of atom:

• It is also known as watermelon model or plum pudding model.
• According to this model, the atom is a positive sphere in which negative charges are distributed.

Rutherford alpha scattering experiment:

• This experiment was performed to understand the structure of an atom.
• This model concludes that most of the part of an atom is empty and each atom consists of a heavy positively charged nucleus.
Fundamental particles of an atom:

 Particle Mass (amu) Charge Discoverer Electron 1.0073 +1 JJ Thomson Proton 1.0087 0 Goldstein Neutron 0.0005 −1 Chadwick

Bohr’s model of atom:

• Electrons orbit the nucleus in orbits which have a set size and energy.
• The lowest energy is found in the smallest orbit.
• Radiation is absorbed or emitted.

• Wavelength: It is the distance between successive points of equal phases of a wave.
• Frequency: It is the number of cycles or oscillations or vibrations of wave motion in unit time.
• Velocity: It is the distance travelled by the wave in one second.
• Wave number: It is defined as the number of waves in unit wavelength.

Heisenberg’s uncertainty principle:
The uncertainty principle says that we cannot measure the position and momentum of the particle with absolute precision.

Bohr–Sommerfield model:

• According to this model, the path of an electron around the nucleus is an ellipse with the nucleus at one of its foci.
• The angular momentum of an electron in a closed elliptical path is also quantised.

Orbital:
An orbital is a three-dimensional region in which the probability of finding an electron is maximum.

Quantum numbers:
Principal quantum number:

• It is denoted by n.
• n = 1, 2, 3, 4 … ∞
• n = 1 K shell; n = 2 L shell
• n = 3 M shell; n = 4 N shell
• As the value of ‘n’ increases, the energy of the electron increases.

Azimuthal or angular quantum number:

• It is denoted by l.
• The values of l are from 0 to (n-1)
• l = 0 s subshell; l = 1 p subshell
• l = 2 d subshell; l = 3 f subshell
• The value of ‘l’ signifies the shape and energy level of subshells in a major energy shell.

Magnetic quantum number:

• It is denoted by ml.
• The values of ml lie from –l to +l.
• The values of ml signify the possible number of orientations of subshells.

Spin quantum number:

• It is denoted by ms.
• The values of ms are +1/2 and −1/2.
• The values of ms signify the direction of rotation or the spin of an electron in its axis during motion.
Shape of orbitals:

 Subshell Shape of orbital s Spherical p Dumbbell d Double dumbbell f Diffused shape

Pauli’s exclusion principle:

• It is impossible for two electrons of an atom to have all its four quantum numbers same.
• Maximum number of electrons in a shell can be 2n2.
• Maximum number of electrons in a subshell can be 2 only.

Aufbau principle:

• Orbitals with lower energy level are filled first.

(n+l) rule:

• The subshell with lower values of (n+l) possesses lower energy.
• If (n+l) for two orbitals are the same, the one with lower value of n possesses lower energy and should be filled first.

Paramagnetism:
A substance whose molecules, ions or atoms have unpaired electrons is paramagnetic.

Diamagnetism:
Molecules, ions or atoms having no unpaired electrons are diamagnetic.

NEET - Chemistry
what is the ratio of T1/T2 in second orbit of hydrogen atom to third orbit of He+ ion
Asked by purvi16saini2004 | 15 Jul, 2022, 06:12: PM
NEET - Chemistry
let 10^-16 J of light energy is required by the interior of human eye to see an object. The number of photons of green light (ý=550)needed to see the object are approximately equal to
Asked by ssolaimuthu9 | 09 Jul, 2022, 02:00: PM
NEET - Chemistry
Consider an atomic species of atomic no.Z and consisting of three electrons which are orbiting equally spaced in the same circular orbit. Let A be the Bohr radius and let the Bohr quantization rule hold for each electron. Then the ground state radius of the three electron atom is-
Asked by shahimanoj61 | 12 Jun, 2022, 06:06: PM
NEET - Chemistry
Consider an Atomic species of atomic no.Z and consisting of three electrons which are orbiting equally spaced in the same circular orbit. Let A be the Bohrs radius and let the Bohrs quantization rule hold for each electron. Then the ground state radius of the three electrons ATOM is
Asked by shahimanoj61 | 12 Jun, 2022, 05:59: PM
NEET - Chemistry
energy of electron in 3rd orbit of hydrogen atom in KJ per mole
Asked by ganirifat0 | 31 Mar, 2022, 05:46: PM
NEET - Chemistry
Solve and explain this
Asked by avikchatterjee557 | 22 Dec, 2021, 09:49: PM
NEET - Chemistry
900 nm wavelength radiation is used in the treatment to relieve muscle pain. So which of the following is similar to this wavelength radiation? (A) Balmer (infinity to 2) (B) Lyman (infinty to 1) (C) paschen (5 to 3) (D) paschen (infinity to 3)
Asked by dodiakanaksinh3 | 13 Sep, 2021, 10:16: PM
NEET - Chemistry
Solve this plz !
Asked by jhajuhi19 | 16 Jul, 2021, 08:42: AM