Here students can locate TS Inter 1st Year Chemistry Notes 1st Lesson Atomic Structure to prepare for their exam.
TS Inter 1st Year Chemistry Notes 1st Lesson Atomic Structure
→ The radiation which is made up of electrical and magnetic fields acting mutually perpendicular to each other is called Electro-magnetic radiation.
→ The number of waves that pass a point in the path of propagation of wave per second is called frequency. It is denoted by υ.
→ The number of waves present in a distance of 1 cm is called wave number. It is the reciprocal of wavelength (i.e.,) υ̅ = 1/λ.
→ According to Planck’s quantum theory emission or absorption of energy takes place in the form of small packets called Quanta. The energy of each quantum of radiation is given by E = hυ.
→ According to Einstein, both emission and absorption of radiation takes place in the form of photons. A photon is a wave particle which has no mass but has energy. The energy of a photon is given by E = hυ.
→ The emission spectrum of hydrogen consists of Lyman series, Balmer series, Paschen series, Bracket series and Pfund series.
→ According to Bohr, electrons revolve around the nucleus in certain definite circular paths, called orbits or energy levels or shells. They are denoted by the letter n.
→ Principal quantum number describes the size of the orbit and energy of the electron.
→ Azimuthal quantum number denotes the shape of the orbital.
→ Magnetic quantum number denotes the special orientation of the orbital.
→ Spin quantum number describes the direction of rotation of the revolving electron.
Its value is + 1/2 for a clockwise electron and – 1/2 for an electron revolving in the anti-clockwise direction.
→ Wave nature of electron was proposed by de Broglie.
→ According to Heisenberg’s uncertainty principle, it is not possible to determine the position and the velocity of a moving particle like electron, simultaneously and accurately.
→ Ψ is known as wave function and Ψ2 is known as probability function.
→ Orbital is the space around the nucleus where the probability of finding the electron is maximum.
→ Orbitals of equal energy are called degenerate orbitals.
→ Arrangement of electrons in space around the nucleus in an atom is known as electronic configuration.
→ According to Pauli’s exclusion principle, an orbital can hold a maximum of two electrons only and a shell can hold a maximum of 2n electrons.
→ Atoms or ions with paired up electron spins * are diamagnetic and with unpaired electron spins are paramagnetic.
→ Atoms or ions with the same electronic configuration are said to be iso-electronic.
→ The wave number u of the spectral lines is given by Rydberg expression,
υ̅ = \(\frac{1}{\lambda}\) = RH\(\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)\)
→ Value of Rydberg constant
(RH) = 109,677 cm-1.
→ Energy of photon, E = hυ.
→ Energy of a photoelectron,
E = hυ = hυ0 + K.E,
where υ0 = threshold frequency.
→ Mass of an electron, m = 9.1 × 10-28 g.
→ Charge of an electron, e =-4.802 × 10-10 e.s.u.
→ Radius of nth orbit
(rn) = 0.529 × 10-8 n2cm.
→ Radius of Bohr’s orbit
(r) = 0.529 × 10-8 cm = 0.529 Å.
→ Energy of electron in the nth orbit,
(En) = \(-\frac{13.6}{n^2}\)eV
→ Value of Rydberg constant (R) = \(\frac{2 \pi^2 \mathrm{me}^4}{\mathrm{ch}^3}\)
→ de Broglie wavelength, λ = \(\frac{\mathrm{h}}{\mathrm{mV}}\).