Much of the study of chemistry involves the interactions between the electrons of different atoms. It is important, therefore, to understand the arrangement of an atom's electrons. This 10-question multiple-choice chemistry practice test deals with the concepts of electronic structure, Hund's Rule, quantum numbers, and the Bohr atom.

Answers to the questions appear at the end of the test.

## Question 1

The total number of electrons that can occupy the principal energy level n is:

(a) 2

(b) 8

(c) n

(d) 2n^{2}

## Question 2

For an electron with angular quantum number ℓ = 2, the magnetic quantum number *m* can have:

(a) An infinite number of values

(b) Only one value

(c) One of two possible values

(d) One of three possible values

(e) One of five possible values

## Question 3

The total number of electrons allowed in a ℓ = 1 sublevel is:

(a) 2 electrons

(b) 6 electrons

(c) 8 electrons

(d) 10 electrons

(e) 14 electrons

## Question 4

A 3p electron can have possible magnetic quantum number values of:

(a) 3 and 6

(b) -2, -1, 0, and 1

(c) 3, 2, and 1

(d) -1, 0, and 1

(e) -2, -1, 0, 1, and 2

## Question 5

Which of the following sets of quantum numbers would represent an electron in a 3d orbital?

(a) 3, 2, 1, -½

(b) 3, 2, 0, +½

(c) Either a or b

(d) Neither a nor b

## Question 6

Calcium has an atomic number of 20. A stable calcium atom has an electronic configuration of:

(a) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}

(b) 1s^{2}1p^{6}1d^{10}1f^{2}

(c) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{2}

(d) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}

(e) 1s^{2}1p^{6}2s^{2}2p^{6}3s^{2}3p^{2}

## Question 7

Phosphorus has an atomic number of 15. A stable phosphorus atom has an electronic configuration of:

(a) 1s^{2}1p^{6}2s^{2}2p^{5}

(b) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}

(c) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}4s^{2}

(d) 1s^{2}1p^{6}1d^{7}

## Question 8

The electrons with principal energy level n = 2 of a stable atom of boron (atomic number of 5) have an electron arrangement of:

(a) ( ↑ ↓ ) ( ↑ ) ( ) ( )

(b) ( ↑ ) ( ↑ ) ( ↑ ) ( )

(c) ( ) ( ↑ ) ( ↑ ) ( ↑ )

(d) ( ) ( ↑ ↓ ) ( ↑ ) ( )

(e) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ) ( ↑ )

## Question 9

Which of the following electron arrangements does not represent an atom in its ground state?

(1s) (2s) (2p) (3s)

(a) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ )

(b) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ )

(c) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ) ( ↑ )

(d) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( )

## Question 10

Which of the following statements is false?

(a) The greater the energy transition, the greater the frequency

(b) The greater the energy transition, the shorter the wavelength

(c) The higher the frequency, the longer the wavelength

(d) The smaller the energy transition, the longer the wavelength

## Answers

1. (d) 2n^{2}

2. (e) One of five possible values

3. (b) 6 electrons

4. (d) -1, 0, and 1

5. (c) Either set of quantum numbers would express an electron in a 3d orbital

6. (a) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}

7. (b) 1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}

8. (a) ( ↑ ↓ ) ( ↑ ) ( ) ( )

9. (d) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( ↑ ↓ ) ( )

10. (c) The higher the frequency, the longer the wavelength