1) Magnetic resonance imaging (MRI), used in hospitals, operate at a frequency o
ID: 542605 • Letter: 1
Question
1) Magnetic resonance imaging (MRI), used in hospitals, operate at a frequency of 4.00 x 102 MHz (1 MHz = 106 Hz) Calculate:
a) the wavelength
b) the energy in joules per photon
c) the energy in kilojoules per mole
2) A line in the spectrum of neon has a wavelength of 837.8 nm
a) in what spectral range does the absorption occur?
b) calculate the frequency of this absorption
c) what is the energy in kilojoules per mole?
3) Energy from radiation can cause chemical bonds to break. To break the nitrogen-nitrogen bond in N2 gas, 941 kJ/mol is required.
a) calculate the wavelength of the radiation that could break the bond
b) in what spectral range does this radiation occur?
4) What factors contribute to the energy of an electron in an atom?
5) Explain what is meant by the quantized energy of electrons.
6) Consider the transition from energy levels n = 1 to n = 3
a) what is the frequency and wavelength associated with this transition?
b) in what spectral region does this transition occur?
c) is energy absorbed?
7) Consider the transition from the energy levels n = 4 to n = 2
a) what is the frequency and wavelength associated with this transition?
b) in what spectra region does this transition occur?
c) is energy absorbed?
8) What are the possible values for ml for
a) the d sublevel?
b) the s sublevel?
c) all sublevels where n = 2?
9) What type of electron orbital (i.e. s, p, d, or f) is designated by
a) n = 2, l = 1, ml = -1?
b) n = 1, l = 0, ml = 0?
c) n = 5, l = 2, ml = 2?
10) State the total capacity for electrons in
a) n = 4 b) a 3s sublevel
c) a d sublevel d) a p orbital
11) What is the
a) minimum n value for l designated as d?
b) letter used to designate the sublevel with l = 2?
c) number of orbitals in a sublevel where l is designated as p?
d) number of different sublevels when n = 3?
12) Given the following sets of electron quantum numbers, indicate those that could not occur and explain your answer.
a) 1, 0, 0, - ½ b) 1, 1, 0, + ½
c) 3, 2, -2, + ½ d) 2, 1, 2, + ½
e) 4, 0, 2, + ½
13) Give the electronic configuration in sublevel notation for the following elements for
which the atomic numbers are given in parentheses.
a) Al (13)
b) Ga (31)
c) Kr (36)
d) Sn (50)
e) Pt (78)
14) Give the orbital diagram for an atom of
1s 2s 2p 3s 3p 4s 3d
a) Na
b) O
c) Co
d) Cl
15) Give the symbol of the atom with the following orbital diagram beyond argon.
4s 3d 4p
a) (¯) (¯)(¯)(¯)( )( ) ( )( )( )
b) (¯) (¯)(¯)( )( )( ) ( )( )( )
c) (¯) (¯)(¯)(¯)(¯)(¯) ( )( )( )
16) Give the number of unpaired electrons in an atoms of
a) mercury
b) manganese
c) magnesium
17) Write the ground state electron configuration for
a) Li, Li+
b) O, O2-
c) Sc, Sc3+
d) Co2+, Co3+
18) Which of the four atoms Na, P, Cl, or K
a) has the largest atomic radius?
b) has the highest ionization energy?
c) is the most electronegative?
19) No currently known elements contain electrons in g (l = 4) orbitals in the ground state. If an element is discovered that has electrons in the g orbital,
a) What is the lowest value for n in which these g orbitals could exist?
b) What are the possible values of ml?
c) How many electrons could a set of g orbitals hold?
20) Describe the shielding effect and how it influences the attraction of a nucleus for outer-
level electrons.
21) Explain how the sizes of the atoms vary within the periods and groups of the periodic
table. In which part of the table are the elements with the smallest atoms found? In
which part of the table are the elements with the largest atoms found?
Explanation / Answer
1)
a)
f = 102 MHz = 1.02*10^8 s-1
use:
lambda = c/f
=(3.0*10^8 m/s)/(1.02*10^8 s-1)
= 2.941 m
Answer: 2.941 m
b)
use:
E = h*f
=(6.626*10^-34 J.s)*(1.02*10^8) s-1
= 6.759*10^-26 J
Answer: 6.76*10^-26 J
c)
Energy of 1 mol = energy of 1 photon * Avogadro's number
= 6.759*10^-26*6.022*10^23 J/mol
= 4.07*10^-2 J/mol
= 4.07*10^-5 KJ/mol
Answer: 4.07*10^-5 KJ/mol
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