2.1. s Orbitals: Spherically symmetric Size increases with increase in size in n, ie, 4s>3s>2s>1s
2.2. p Orbitals: Each p Orbitals consists of two sections called lobes on either side of plane passing through the nucleus.
2.3. d Orbitals : ‘’Clover leaf ’’ distribution. – Two angular nodes.
3. energy of orbitals
3.1. Lower the value of ( +l) for an orbital, n lower is its energy
4. Developments leading to bohrs model of atoms
4.1. Dual nature ie wave like and particle like of the electromagnetic radiation. • Experimental results regarding atomic spectra. • Wave nature of electromagnetic radiation: It was given by James Maxwell. Js
4.2. Frequency: Number of waves that pass a given point in one second. Unit – Hertz (Hz), Velocity of light = Frequency × Wave length wavenumber: Number of wavelengths per Wave number unit length. Unit – m-1 • Particle nature of electromagnetic radiation: Planck's quantum theory: E= hv Planck's constant (h) = 6.626 × 10^-34 Js
5. photoelectric effect
5.1. It is the phenomenon of ejection of electrons from the surface of a metal when light of suitable frequency strikes on it.
6. By James Rutherford Charge on neutron - 0 Mass of neutron - 1.675 x 10²7 Kg
7. Isobars
7.1. Atoms of different elements with different atomic number but same mass number.
9.1. •Aufbau Principle: In the ground state of atoms, the orbital's are filled according to increasing energies and fill up the lower energy first.•Pauli's Exclusion Principle: No 2 electrons in an atom can have identical set of four quantum numbers . •Hund's rule of maximum multiplicity : Electrons remain unpaired and posses same direction of spin as far as possible ,Pairing of electrons in the orbitals belonging to same subshell does not take place until each electron belonging to the subshell is singly occupied.
10. Isotopes
10.1. Atoms of same element having same atomic number but different mass number (Isotopes of hydrogen) Protium 'H₁, Deuterium "D, and Tritium "T₁
11. Discovery of Electrons
11.1. By J.J.Thomson Charge to mass ratio of electron = 1.758820 x 10" C kg" Charge an electron = 1.6022 x 10¹⁹C Mass of electron = 9.1094 x 10³¹ Kg
12. Discovery of Protons
12.1. By Ernest Rutherford Charge on proton +1.6022 x 10""C Mass of Proton 1.672 × 10 Kg
13. Discovery of Neutrons
14. Thompson Model Of Atom (Plum pudding model)
14.1. Atom possesses a spherical shape in which the positive charge is uniformly distributed
15. Rutherford Nuclear Model of atom
15.1. Postulates: • Positive charge and most of the mass of atoms was densely concentrated in extremely small region (ie) nucleus. • Nucleus is surrounded by electrons that move around the nucleus with high speed in circular path called orbits. • Electrons and nucleus are held together by electrostatic forces of attraction.
