THERE ARE NO MANUAL TO THIS BOOK, THEREFORE WOULD LIKE TO KNOW IF IM DOING THESE

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THERE ARE NO MANUAL TO THIS BOOK, THEREFORE WOULD LIKE TO KNOW IF IM DOING THESE RIGHT. ANYONE WITH ANSWERS ??

1. What frequency of light is emitted when an electron jumps into the smallest
orbit of hydrogen, coming from a very large radius (assume infinity)?

2. Calculate the energy in electron-volts of the electron orbit in hydrogen for
which n ¼ 3, and find the radius in centimeters. How much energy would
be needed to cause an electron to go from the innermost orbit to this one?
If the electron jumped back, what frequency of light would be observed?

3. What is the radius of the nucleus of uranium-238 viewed as a sphere? What
is the area of the nucleus, seen from a distance as a circle?

Find the binding energy in MeV of ordinary helium, 42
He, for which
M ¼ 4.002603.

4. How much energy (in MeV) would be required to completely dissociate
the uranium-235 nucleus (atomic mass 235.043923) into its component
protons and neutrons?

5. Find the mass density of the nucleus, the electrons, and the atom of U-235,
assuming spherical shapes and the following data:
Atomic radius 1.7 1010 m
Nuclear radius 8.6 1015 m
Electron radius 2.8 1015 m
Mass of 1 amu 1.66 1027 kg
Mass of electron 9.11 1031 kg

Explanation / Answer

1) E(n) = E1 *(1/n^2-1/m^2)

m = infinity and n=1

E(1) = E1 =13.6 eV

E = h*F

F = E/h =13.6*1.6*10^-19/6.626*10^-34 =3.284*10^15 Hz

2) n =3 m=infinity

E(3) = 13.6/9 =1.51 eV

from the most innermost orbit we have

n=1 m=3

E(1-3) = 13.6*(1/1 -1/9) =12.088 eV

The radius of the 3rd orbit is

r(3) = r(1)*n^2 =0.53*10^-10*9 =4.77*10^-10 m =4.77*10^-8 cm

r(1) =0.53*10^-10 m is the radius of first orbit

3) R =r0*A^(1/3)

r0 =1.25*10^-15 m

R =1.25*10^-15 *238^0.333 =7.746*10^-15 m

S =4*pi*R^2 =754*10^-30 m^3

4) m(neutron) =1.00866 amu

m(proton) =1.6726*10^-27 kg =1.00728 amu

(238,92)U mass =238.05 amu

mass defect is

delta(m) = 238.05 -92*1.00728 -146*1.00866 = -1.884 amu

energy is

E = delta(m) *c^2 =1.884*1.66*10^-27*(3*10^8)^2 =2.815*10^-10 J =1759.2 MeV

5)235U mass =235.04 amu =3.9*10^-25 kg

atom volume V1 = 4*pi*R^3/3 =2.06*10^-29 m^3

nuclear voulume V2 =4*pi*r^3/3 =2.66*10^-42 m^3

electron volume V3 =9.19*10^-44 m^3

atomic density is ro1 =3.9*10^-25/2.06*10^-29 =1.89*10^4 kg/m^3

nuclear density is ro2 =3.9*10^-25/2.66*10^-42 =1.47*10^17 kg/m^3

electron density is ro3 =9.11*10^-31/9.19*10^-44 =9.91*10^12 kg/m^3

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