Structure of Atom

Question 1

Electromagnetic Radiation

Answer 1

Charged particles under acceleration producing alternating electrical and magnetic fields

Question 2

Isotopes vs Isobars vs Isotones

Answer 2

Isotopes: Atoms of the same element which have the same atomic numbers but different mass numbers
Isobars: Atoms of different elements having the same mass numbers but different atomic numbers
Isotones: Atoms having same number of neutrons but different mass numbers

Question 3

Relation between c, mu, lambda

Answer 3

c = (mu)(lambda)

Question 4

Wavenumber

Answer 4

Number of wavelengths per unit length = 1 / lambda

Question 5

Give the electromagnetic spectrum (in increasing wavelength)

Answer 5

gamma rays < X rays < UV < visible < IR < Microwave < FM < AM < long radio

Question 6

Give the electromagnetic spectrum (in increasing frequency)

Answer 6

Long radio > AM > FM > Microwave > IR > visible > UV > X rays > gamma rays

Question 7

Black Body Radiation Explanation

Answer 7

• When solids are heated they emit radiation over a wide range of wavelengths
• When an iron rod is heated, it turns to dull red and then progressively more and more red as temp increases

Question 8

What is black body radiation?

Answer 8

The ideal black body, which emits and absorbs radiations of all frequencies, is called a black body and the radiation emitted by such a body is black body radiation

Question 9

Relation between E, h, mu

Answer 9

E = h (mu)

Question 10

Photoelectric effect + results

Answer 10

Electrons are ejected from certain metals when exposed to a beam of light
* Ejected as soon as light strikes the surface
* No. of electrons proportional to intensity
* Existence of minimum frequency

Question 11

Relation between intensity and no. of electrons ejected

Answer 11

Directly proportional

Question 12

Threshold frequency

Answer 12

Frequency below which photoelectric effect is not observed

Question 13

Relation between frequency and KE

Answer 13

Directly proportional (Greater energy by photon = greater KE - greater frequency of photon)

Question 14

Photoelectric effect equation

Answer 14

h(mu) = h(mu0) +1/2 mv^2

Question 15

Longest wavelength

Answer 15

Red colour

Question 16

Spectrum

Answer 16

Ray of white light is spread out into a series of coloured bands

Question 17

Emission spectrum

Answer 17

Spectrum of radiation emitted by a substance that has absorbed energy

Question 18

Absorption spectrum

Answer 18

When light is passed through unexcited atomic hydrogen and transmitted light is lacking in intensity

Question 19

Wavenumber formula (Rydberg’s)

Answer 19

(mu)_ = 109,677 (1/n1^2 - 1/n2^2) cm^-1

Question 20

Angular momentum formula

Answer 20

mvr = nh/2pi

Question 21

All light spectrum correspondance

Answer 21

Lyman - Ultraviolet (Till n=1)
Balmer - Visible (Till n = 2)
Paschen - Infrared (Till n=3)

Question 22

Formula of radius of bohr orbit

Answer 22

r = a(n^2)/Z
a = 52.9 pm

Question 23

Convert:
1) picometer
2) nanometer
3) Armstrong
4) Micrometer

Answer 23

1) 10^-12m
2) 10^-9m
3) 10^-10m
4) 10^-6m

Question 24

Ionized hydrogen atom

Answer 24

When an electron is taken free from the influence of nucleus, the energy is taken as zero. The electron in this situation is associated with the stationary state of Principal Quantum Number = n = infinity

Question 25

Formula of E {Rydberg's}

Answer 25

E = -Rh(Z^2/n^2) Rh = 2.18 * 10^-18J

Question 26

Magnitude of velocity of electron

Answer 26

Increases with positive charge on nucleus Decreases with increase in principal quantum number

Question 27

For which species can Bohr's theory by applied

Answer 27

* Isoelectronic species having one electron * H, He+, Li2+, Be3+, etc.

Question 28

What happens when n1 > nf

Answer 28

Delta E is negative and energy is released

Question 29

What does the brightness / intensity of spectral depend upon?

Answer 29

Number of photons of same wavelength or frequency absorbed or emitted

Question 30

Relation between wavelength and momentum (dual behavior)

Answer 30

lambda = h / mv = h / p

Question 31

Heisenberg Uncertainty Principle

Answer 31

Impossible to determine simultaneously, the exact position and exact momentum of an electron

Question 32

Heisenberg Uncertainty Principle Formula

Answer 32

delta x * delta mv >= h / 4 pi

Question 33

Principal quantum number

Answer 33

* Determines size and to large extent the energy of the orbit * Identifies the shell * Ranges from 1 to n

Question 34

Number of allowed orbitals

Answer 34

n^2

Question 35

With increase in 'n' value what increases?

Answer 35

* Energy * Size of orbital

Question 36

Azimuthal quantum number

Answer 36

Defines the 3D shape of the orbital

Question 37

What do 'l' values range from

Answer 37

0 to (n-1)

Question 38

How many subshells are there?

Answer 38

n total

Question 39

Magnetic orbital quantum number

Answer 39

Gives information about spatial orientation of the orbit with respect to standard set of co-ordinate axis

Question 40

How many possible values of magnetic quantum number

Answer 40

2l + 1

Question 41

Electron spin

Answer 41

Can have two orientations relative to chosen axis {Spin of the electron}

Question 42

nodes

Answer 42

Refers to the area / region where probability density function reduces to zero

Question 43

Nodes: 1) Total 2) Radial 3) Angular

Answer 43

1) n-1 2) n - l -1 3) l

Question 44

Draw 2px, 2py, 2pz

Answer 44

-

Question 45

Draw dxy, dyz, dxz, d(x^2-y^2), dz^2

Answer 45

-

Question 46

Degenerate

Answer 46

Orbitals having the same energy

Question 47

Effective nuclear charge

Answer 47

The attractive positive charge of nuclear protons acting on valence electrons

Question 48

Formula of Zeff

Answer 48

Zeff = Z - S Z = atomic number S = number of shielding electrons

Question 49

Relation between l and Zeff and why?

Answer 49

Inversely proportional Increase in azimuthal causes s electron to be more tightly bound to the nucleus than p electron which in turn will be more tightly bound than the d electron

Question 50

Energy of orbit formula (using n and l values)

Answer 50

n+l

Question 51

Aufbau Principle

Answer 51

In the ground state of the atoms, the orbitals are filled in order of increasing energies

Question 52

Pauli Exclusion Principle

Answer 52

* No two electrons in an atom can have the same set of four quantum numbers * Only two electrons may exist in the same orbital and these electrons must have opposite spin

Question 53

Maximum number of electrons in shell with principal quantum number n

Answer 53

2n^2

Question 54

Hund's rule of maximum multiplicity

Answer 54

Pairing of electrons in the orbitals belonging to the same subshell does not take place until each orbital belonging to that subshell has got one electron each

Question 55

Valence Electrons

Answer 55

Electrons in the completely filled shells are known as core electrons and electrons added to electronic shell with highest principal quantum number

Question 56

Config of copper and chromium

Answer 56

Chromium: 1s2 2s2 2p6 3s2 3p6 4s1 3d5 Copper: 1s2 2s2 2p6 3s2 3p6 4s1 3d10

Question 57

Explain copper and chromium's electronic config

Answer 57

* Fully filled and half-filled orbitals have extra stability * Hence, they take on that config

Question 58

Causes of stability of completely filled and half filled sub-shells

Answer 58

* Symmetrical distribution of electrons * Exchange energy - Maximum and hence max stability

Question 59

Fe2+ configuration

Answer 59

1s2 2s2 2p6 3s2 3p6 3d6 We have to remove from the valence electron shell first