Structure of Atom

Question 1

Charge to Mass Ratio

Answer 1

e/me = 1.75 x 10^11 C/kg

Question 2

Charge of electron

Answer 2

-1.6 x 10^-19 C

Question 3

Mass of Electron

Answer 3

me = 9.1 x 10^-31 kg

Question 4

Charge to mass ratio of proton

Answer 4

e/m = 9.58 x 10^7 C/kg

Question 5

Mass of proton of hydrogen

Answer 5

1.67 * 10^-27 kg

Question 6

Bohr model for Hydrogen Atom (Orbits, jumping, frequency, momentum)

Answer 6

1. Electrons move around in orbits with fixed radius and energy, concentrically arranged around the nucleus.
2. Energy of an electron in orbit does not change over time. Though electrons will change orbits when required amounts of energy are absorbed or emitted.
3. Freq of radius absorbed or emitted during transition is given by…
   v = ΔE/h = E2 - E2/h
4. Angular momentum at orbit is…
   me.v.r = n.h/2π (n=1,2,3…)

Question 7

According to Bohr’s model of H atom, radii of orbit is…

Answer 7

rn = n^2 . a0 (a0 = 52.9pm)

Question 8

According to Bohr’s model of H atom, energy at an orbit is…

Answer 8

En = -Rh (1/n^2) (Rh = 2.18x10^-18)

Question 9

According to Bohr’s model of H atom, energy at orbit for ions is…

Answer 9

En = Rh (Z^2/n^2) J

Question 10

According to Bohr’s model of H atom, radii of orbits of ions is…

Answer 10

rn = 52.9 . n^2/Z

Question 11

List the limitations of Bohr’s Model of an atom (finer, more electrons, splitting, bonding)

Answer 11

1. Failed to explain finer details of hydrogen spectrum (doublet)
2. Could not explain the spectrum of atoms containing more than one electron
3. Unable to explain the splitting of spectral lines in presence of magnetic/electric fields
4. Could not explain the ability of atoms to form molecules by chemical bonds

Question 12

Balmer Series Formula

Answer 12

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

Question 13

Formula of Electromagnetic Radiation

Answer 13

c = vλ (v = freq, λ = wavelength, c = speed of light)

Question 14

Formula for Wave Number

Answer 14

v = 1/λ cm-1