Atoms

Question 1

what did Thomson model explain

Answer 1

1) uniformly distributed positive charge
2) electron->watermelon seed
3)plum pudding model

Question 2

limitation of the Thomson model

Answer 2

1) origin of spectral series
2)alpha particle scattering

Question 3

Rutherford model

Answer 3

1)small and massive central core of +ve charge
2)the size of nucleus is very small

Question 4

Rutherford model limitation

Answer 4

1)cannot explain the stability of atom
2)they would emit a continuous spectrum instead of the actually observed line spectrum

Question 5

BOHR’S ATOMIC MODEL

Answer 5

1)Electrons revolve around the nucleus in fixed circular paths called
Orbits or Shells.
2)Electron in its own shell does not lose or gain energy. It loses or
gains energy when it jumps from one shell to another
3)The Angular Momentum of electron is quantized in the shell.
L = (nh)/(2pi)

Question 6

Bohr radius of hydrogen

Answer 6

r = 0.53 (n^2)/z A

Question 7

bohr radius formula

Answer 7

(Eon^2h^2)/pimz*e^2

Question 8

velocity of electron

Answer 8

v = 2.186 x 10^6 * z/n

Question 9

potential energy of electron

Answer 9

P.E=-e^2/(4piEo*r)

Question 10

energy of hydrogen in the Nth orbit

Answer 10

E=-13.6/n^2 eV

Question 11

energy of atom

Answer 11

-2pi^2mk^2e^4/h^2*n^2

Question 12

frequency of emitted photon

Answer 12

h*mu=En2-En1

Question 13

Rydberg formula for the spectrum of hydrogen series

Answer 13

wave number=r[1/(n1^2)-1/(n2^2)]
r->rydberg constant->1.097310^7 m^-1

Question 14

lyman series

Answer 14

electron jumps from higher energy level to n=1 energy level
ultraviolet region
wave number=R[1/(1^2)-1/(n2^2)]

Question 15

balmer series

Answer 15

electron from n=3,4,4,etc to n=2
visible region
wave number=R[1/(2^2)-1/n2^2]

Question 16

paschen series

Answer 16

electron from n=4,5,,etc to n=3
infrared region
wave number =R[1/3^2-1/n2^2]

Question 17

brackett series

Answer 17

electron from n=5,6,etc to n=4
infrared region
wave number=R[1/4^2-1/n2^2]

Question 18

pfund series

Answer 18

electron from n=6,7,etc to n=5
infrared region
wave number=R[1/5^2-1/n2^2]

Question 19

limitation of bohr theory

Answer 19

-> This theory is only applicable for hydron-like series
-> Why only circular orbits not elliptical orbits
->electron has a wave nature so orbits of electrons are not defined
->does not explain the further splitting of spectral lines in a magnetic
and electric field

Question 20

excitaion energy

Answer 20

energy required to jump from lower to higher state

Question 21

ionisation energy

Answer 21

energy required to remove an electron from an atom

Question 22

relationship between kinetic energy and potential energy

Answer 22

P.E=-2 K.E