Exam 3: Question 16-40
#28: Boron has primarily two isotopes, one with an atomic mass of 11 amu and another with an atomic mass of 10 amu. If the abundance of the boron atom with a mass of 11 amu is 18.9 percent and the abundance of the other isotope is 81.1 percent, what would be the average mass of the boron atom?
10.19 amu
#38: The diameter of an average atom is about
10^-10 m.
#39: The diameter of an average nucleus is about?
10^-14 m.
#32: Which is not a possible value for the principal quantum number n?
3.5
#31: Which color of light comes from a greater energy transition?
Blue
#36: Who discovered the atomic nucleus in 1911?
Ernest Rutherford
#26: A beam of protons and a beam of neutrons of the same energy are both harmful to living tissue. The beam of neutrons, however, is less harmful. Why?
Neutrons carry no electric charge and thus have a greater likelihood of passing through the tissue.
#27: Evidence for the existence of neutrons did not come until many years after the discoveries of the electron and the proton. Give a possible explanation.
The neutron lacks an electrical charge
#29: Calculate the de Broglie wavelength for an electron (m = 1 * 10^-30 kg) moving at 3.3 * 10^6 m/s.
lambda = h/(mv)
#18: Light will not pass through a pair of Polaroids when their axes are
perpendicular.
#16: Relative to ultraviolet waves, the wavelength of gamma rays is
shorter
#37: The various isotopes of an element all have
the same number of protons but different numbers of neutrons.
#30: Photons of ultraviolet light are responsible for sun tanning. Find the wavelength of an ultraviolet photon whose energy is 6.4 x 10-19 J.
(6.626*〖10〗^(-34) )(3*〖10〗^8 )/(6.4*〖10〗^(-19) )=3.1*〖10〗^(-7)
#40: A bacterium (m = 2 x 10-15 kg) in the blood moves at 0.33 m/s. What is the de Broglie wavelength?
(6.626*〖10〗^(-34))/[(2*〖10〗^(-15) )(.33)] =1.0*〖10〗^(-18)
#19: Which contributes more to an atom's mass: electrons or protons? Which contributes more to an atom's size?
Protons contribute more to an atom's mass while electrons contribute more to its size.
