Chemistry I-Honors
Electron Configuration / Quantum Numbers
Practice Test Solution Set
1.
2
10
2
Give the inert gas core configuration for a neutral atom of tin.
2.
Which of the following is the highest energy subshell in the telluride ion (Te
-2
) ?
A) 6d; B) 7s; C) 5d; E) 6p; F) 4p; G) 5f; H) 5p
3.
If the highest-energy electron in a neutral atom has the following set of quantum numbers: n = 4 l = 2 m = -1 s = +1/2, which element is being described?
[ the highest energy electron being described is 4d 7 ]
4.
2
10
6
Give the inert gas core configuration for the arsenide ion ( As
-3
).
(I'm not asking just for the noble gas - I'm asking for the entire configuration!)
5. 4 2 -1 +1/2 What is the set of quantum numbers for the 45th electron in a neutral atom
n l m s of francium?
6.
What is the wavelength ( in nm ) of a photon if its frequency is 4.42 x 10
14
sec
-1
?

17
14
-1
7.
What is the type of electromagnetic radiation described in question #6?
A) red light; B) blue light; C) X rays; D) microwaves; E) IR; F) gamma rays.
Consider this complete electron configuration for the following neutral element:
1s
2
2s
2
2p
6
3s
2
3p
6
4s
2
3d
10
4p
6
5s
2
4d
10
5p
6
6s
2
4f
14
5d
10
6p
5
8.
What is the highest energy subshell in this element?
9.
What is the chemical symbol for the element being described?
10.
What is the total number of subshells within this element?
11.
What is the classification of this element?
A) alkali metal; B) transition metal; C) rare earth metal; D) chalcogen; E) halogen
12.
- F Based on the electron arrangement, this element would be paramagnetic .
(has unpaired electrons)
13.
- F Based on the Z number , this element would be radioactive .
(has a Z # greater than 83)
14.
What is the set of quantum numbers for the highest energy electron
n l m s in a neutral atom of this element?

-2-
15.
-19
J How much energy ( in joules ) is emitted when a single photon with a wavelength of 11,050 Angstroms is released?

E = hc /

= (6.626 x 10 -34 J-sec)(3.00 x 10 18 A/sec) / 11,050 A

E = 1.7989 x 10 -19 joules
16.
Which of the following forms of electromagnetic radiation possesses the greatest energy per photon? A) X rays; B) cosmic rays; C) radio waves; D) microwaves; E) visible light
17.
In a chemical reaction the removal or movement of what type of electron is associated with the visible range color of the salts of transition metals?
A) s orbtial; B) p orbital; C) d orbital; D) f orbital.
18.
In describing the dual nature of light, we say that electromagnetic radiation can have a particulate nature. What is this term for a "packet" of light?
19.
An atom of iridium (Z# = 77) has a total of how many " p " electrons in a neutral atom?
20.
What is the number of orbitals in a subshell if the azimuthal quantum number (l) = 3 ?
21.
Which of the following sets of quantum numbers is/are acceptable for an electron of a neutral atom of radium (Z# = 88)? Note: This does not necessarily mean the highestenergy electron. n
1) 6
2)
3)
4
5 l
0
2
3 m s
1
-2
0
-1/2
+1/2
+1/2
4)
5)
6) n
2
7
6 l
2
0
2 m
-1
0
-2 s
+1/2
-1/2
-1/2
5f not there yet 6d not there yet
A) only 2; B) only 3; C) only 6; D) both 3 &4; E) both 1 & 5; F) both 2 & 5.
22.
Which of the following species is isoelectronic with a neutral xenon atom?
A) Sn
+4
; B) Sb
-3
; C) Bi
+3
; D) Br
-
; E) La
+3
; F) both B & C; G) both B and E.
[ “Isoelectronic” means that they have the same number of electrons.]
23.
What element is it whose neutral, isolated atom has two valence electrons in the 5s subshell, two half-filled orbitals and one empty orbital in the 5p subshell (in addition to its core electrons)? [ 5s 2 5p 2 ]

-3-
24. Give the core electron configuration for a neutral copper atom. Explain the two reasons for this abnormality.
1
10
rd
25.
How many electrons are needed to fill the "M" shell? [ M is the 3 rd shell.]
26.
How many shells are either filled or partially filled in a neutral atom of bohrium (Z # =
107)?
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27-28. Essays:
Choose two of the following topics to answer. Use the back of this page if necessary. Be clear, yet concise . One or two of the others may be done for extra credit (3 pts each). Write "EC" beside those that you choose for EC.
No extra time will be given in order to do any extra credit work, though!
1. Compare and contrast the work of Balmer and Lyman.
2. State the Heisenberg Uncertainty Principle and explain its importance .
3. Explain the significance of de Broglie's "matter waves".
4. Explain how Einstein's photoelectric effect was related to the study of electron movement.
5. State the Pauli Exclusion Principle and explain its importance in terms of the energy of electrons.
6. Explain how Einstein’s photoelectric effect ties in with electron configuration.

1. Balmer and Lyman both studied the absorption spectra of elements. From their work, the energy of the shells was more accurately determined. The difference in their work was that
Balmer started from the first excited state, whereas Lyman started from the ground state.
Balmer did his work first. The reason Balmer started from the first excited state was that the spectra he observed was in the visible range. Lyman’s work, in contrast, with the larger energy difference, moved his spectra into the UV range.
2. The Heisenberg Uncertainty Principle states that both the position and the velocity of an electron cannot be known with absolute certainty simultaneously. The more accurately one factor is less, the less accurately the other one is known.
3. de Broglie’s “matter waves” were an extension of thought to the dual nature of light. Since light was known to exhibit both wave-like properties as well as a particulate nature (photons), then he surmised that matter - which obviously has a particulate nature - could also have wave-like properties. For pieces of matter like electrons, which have negligible mass and high velocities, they do indeed exhibit a wave-like motion. This property allows the electron to maintain its energy as it stays in motion around the nucleus of an atom.
4. Einstein’s photoelectric effect was important to the advance of the study of electrons because it showed that electrons only exist in certain shells. It took certain amounts of light (photons) to excite an electron from the surface of a metal. This amount of light corresponded to the energy of the shell.
5. The Pauli Exclusion Principle states that no two electrons in any given atom can have the same set of four quantum numbers. If two electrons had the same set of four quantum numbers, that would imply that they occupied the same space, which is impossible. In terms of energy, it also implies that they have different energies. Even though the orbitals within a subshell may be
“degenerate” - have the same energy - each electron has a unique amount of energy. As electrons are added to a particular subshell, each successive electron must have more energy than the previous one (because of the Z effective
and to overcome any electron-electron repulsion).
6. Similar to the response of question #4. The difference is that - in terms of electron configuration
- the photoelectric effect allowed scientists to actually measure the color of light needed to excite electrons from the metal’s surface. For example, the salts of the transition metals are noted for their color. This color comes as electrons jump back and forth within the “d” subshell, or between the “d” and the “s” subshells.