Electron Configuration Practice Questions

Chemistry End of Chapter Exercises

Read the labels of several commercial products and identify monatomic ions of at least four transition elements contained in the products. Write the complete electron configurations of these cations.

Read the labels of several commercial products and identify monatomic ions of at least six main group elements contained in the products. Write the complete electron configurations of these cations and anions.

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For example, Na+: 1s22s22p6;
Ca2+: 1s22s22p63s23p6;
Sn2+: 1s22s22p63s23p63d104s24p64d105s2; F–: 1s22s22p6; O2–: 1s22s22p6; Cl–: 1s22s22p63s23p6.

Using complete subshell notation (not abbreviations, 1s22s22p6, and so forth), predict the electron configuration of each of the following atoms:

(a) C

(b) P

(c) V

(d) Sb

(e) Sm

Using complete subshell notation (1s22s22p6, and so forth), predict the electron configuration of each of the following atoms:

(a) N

(b) Si

(c) Fe

(d) Te

(e) Tb

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(a) 1s22s22p3; (b) 1s22s22p63s23p2; (c) 1s22s22p63s23p64s23d6; (d) 1s22s22p63s23p64s23d104p65s24d105p4; (e) 1s22s22p63s23p64s23d104p65s24d105p66s24f9

Is 1s22s22p6 the symbol for a macroscopic property or a microscopic property of an element? Explain your answer.

What additional information do we need to answer the question “Which ion has the electron configuration 1s22s22p63s23p6”?

Solution

The charge on the ion.

Draw the orbital diagram for the valence shell of each of the following atoms:

(a) C

(b) P

(c) V

(d) Sb

(e) Ru

Use an orbital diagram to describe the electron configuration of the valence shell of each of the following atoms:

(a) N

(b) Si

(c) Fe

(d) Te

(e) Mo

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(a)

This figure includes a square followed by 3 squares all connected in a single row. The first square is labeled below as, “2 s.” The connected squares are labeled below as, “2 p.” The first square has a pair of half arrows: one pointing up, and the other down. Each of the remaining squares contains a single upward pointing arrow.



(b)

This figure includes a square followed by 3 squares all connected in a single row. The first square is labeled below as, “2 s.” The connected squares are labeled below as, “2 p.” The first square has a pair of half arrows: one pointing up and the other down. The first two squares in the row of connected squares contain a single upward pointing arrow. The third square is empty.



(c)

This figure includes a square followed by 5 squares all connected in a single row. The first square is labeled below as, “4 s.” The connected squares are labeled below as, “3 d.” The first square and the left-most square in the row of connected squares each has a pair of half arrows: one pointing up and the other down. Each of the remaining squares contains a single upward pointing arrow.



(d)

This figure includes a square followed by 3 squares all connected in a single row. The first square is labeled below as, “5 s superscript 2.” The connected squares are labeled below as, “5 p. superscript 4.” The first square and the left-most square in the row of connect squares each has a pair of half arrows: one pointing up and the other down. Each of the remaining squares contains a single upward pointing arrow.



(e)

This figure includes a square followed by 5 squares all connected in a single row. The first square is labeled below as, “5 s.” The connected squares are labeled below as, “4 d superscript 5.” Each of the squares contains a single upward pointing arrow.

Using complete subshell notation (1s22s22p6, and so forth), predict the electron configurations of the following ions.

(a) N3–

(b) Ca2+

(c) S–

(d) Cs2+

(e) Cr2+

(f) Gd3+

Which atom has the electron configuration 1s22s22p63s23p64s23d104p65s24d2?

Solution

Zr

Which atom has the electron configuration 1s22s22p63s23p63d74s2?

Which ion with a +1 charge has the electron configuration 1s22s22p63s23p63d104s24p6? Which ion with a –2 charge has this configuration?

Solution

Rb+, Se2−

Which of the following atoms contains only three valence electrons: Li, B, N, F, Ne?

Which of the following has two unpaired electrons?

(a) Mg

(b) Si

(c) S

(d) Both Mg and S

(e) Both Si and S.

Solution

Although both (b) and (c) are correct, (e) encompasses both and is the best answer.

Which atom would be expected to have a half-filled 6p subshell?

Which atom would be expected to have a half-filled 4s subshell?

Solution

K

In one area of Australia, the cattle did not thrive despite the presence of suitable forage. An investigation showed the cause to be the absence of sufficient cobalt in the soil. Cobalt forms cations in two oxidation states, Co2+ and Co3+. Write the electron structure of the two cations.

Thallium was used as a poison in the Agatha Christie mystery story “The Pale Horse.” Thallium has two possible cationic forms, +1 and +3. The +1 compounds are the more stable. Write the electron structure of the +1 cation of thallium.

Solution

1s22s22p63s23p63d104s24p64d105s25p66s24f145d10

Write the electron configurations for the following atoms or ions:

(a) B3+

(b) O–

(c) Cl3+

(d) Ca2+

(e) Ti

Cobalt–60 and iodine–131 are radioactive isotopes commonly used in nuclear medicine. How many protons, neutrons, and electrons are in atoms of these isotopes? Write the complete electron configuration for each isotope.

Solution

Co has 27 protons, 27 electrons, and 33 neutrons: 1s22s22p63s23p64s23d7. I has 53 protons, 53 electrons, and 78 neutrons: 1s22s22p63s23p63d104s24p64d105s25p5.

Write a set of quantum numbers for each of the electrons with an n of 3 in a Sc atom.