Structure of Atom Flashcards
(25 cards)
What is radiation
A mode of transference of energy
What is wavenumber
It is the number of waves per metre. (1/wavelength )
What is the electromagnetic spectrum
The arrangement of different types of electromagnetic radiations in decreasing order of their wavelengths
State the order of the electromagnetic spectrum
radio>micro>infra>visible>UV>X>gamma>cosmic
Why couldnt E.W.T explain black body radiation
Because according to it, only one colour should have been emitted irrespective of temperature
What is photoelectric effect
The ejection of electrons when a radiation of threshold frequency falls on the surface on the metal
State the postulates of Plank’s Quantum theory
- Energy is absorbed or emitted discontinuously in small packets
- Each packet of energy is a quantum and the quantum of light is a photon
- Energy of photon = hv
- A body can absorb or emit only a whole number multiple of one photon
What is emission spectra
It is the spectrum obtained when radiations emitted by the excited substance are analyzed by a spectroscope. It has bright lines separated by dark spaces
What is absorption spectrum
The spectrum is obtained when white light is passed through a substance in a gaseous or solution state. It consists of a band of colours with dark lines
Name the scientists which study the different parts of the line spectrum
UV - Lyman - n1
Visible - Balmer - n2
Infrared - Paschen - n3
Infrared - Brackett - n4
Infrared - Pfund - n5
How to calculate the wavelength for hydrogen spectrum
(1/Wavelenght) = 109678(1/n1^2 - 1/n2^2) where n1 is the final shell
What is the energy of a shell
(-2 * π^2 * Z^2 * e^4 * m)/ (n^2 * h^2)
What is Bohr’s model of atom
- Electrons move in fixed non-radiating orbits called stationary states
- Each stationary state has a fixed energy so it is known as energy levels
- Only shells with angular momentum (mvr) which is a whole no. multiple oh h/2pi is permitted
- Energy is quantized
- electrons have a normal state with doesn’t lose energy
How to calulate number of lines in spectru
n(n-1)/2 where n is the outermost shell
What is Heisenberg theory
It is impossible to know the exact position and momentum of a subatomic particle at the same time
What does De Broglie state
That all materials posses in motion posses wave nature
wavelength = h / mv
The mathematical statement of Heisenberg uncertainty principle
Δx . Δp =>= h/4π
What are quantum numbers
They are the index numbers which are used to specify the position and energy of an electron in the atom
What are the four quantum number
Principal (n) - energy level
Azimuthal (l) - subshell
Magnetic (m) - orientation of orbital
Spin (s) = +1/2, -1/2
How to calculate the total number of electrons in a subshell
2(2l+1)
What is the maximum number of orbitals in a shell
n^2
What does Pauli’s exclusion principle state
No two electrons in an orbital of an atom can have the same 4 quantum numbers ( no two electrons with same spin can fill an orbital)
How many nodes does s orbital have
(n-1) when n is the energy level
How many nodes does p orbital have
(n-2)
