Q: A sample of chlorine contains two isotopes: $$^{35}\mathrm{Cl} (75.8$$% abundance, mass = 34.97 amu) and $$^{37}\mathrm{Cl} (24.2$$% abundance, mass = 36.97 amu). What is the average atomic mass of chlorine?

$$(0.758 \times 34.97) + (0.242 \times 36.97) = 35.45\ \mathrm{amu}$$

Q: A photon of light has a wavelength of $$500\ \mathrm{nm}. $$What is its frequency? (Speed of light $$c = 3.00 \times 10^8$\ \mathrm{m/s})$$

$$6.00 \times 10$$^{14}$$\ \mathrm{Hz}$$

Question 1

Which of the following correctly describes the difference between ionic and molecular compounds?

Accepted Answer

Ionic compounds are formed from the transfer of electrons between metals and nonmetals, while molecular compounds are formed from the sharing of electrons between nonmetals.

Question 2

Which of the following is the correct electron configuration for a neutral atom of phosphorus ($$Z = 15$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^3$$

Question 3

A sample of chlorine contains two isotopes: $$^{35}\mathrm{Cl} (75.8$$% abundance, mass = 34.97 amu) and $$^{37}\mathrm{Cl} (24.2$$% abundance, mass = 36.97 amu). What is the average atomic mass of chlorine?

Accepted Answer

$$(0.758 	imes 34.97) + (0.242 	imes 36.97) = 35.45\ \mathrm{amu}$$

Question 4

Which of the following statements about the Gold Foil Experiment is correct?

Accepted Answer

It showed that atoms have a small, dense, positively charged nucleus.

Question 5

Which of the following compounds is named correctly?

Accepted Answer

NaCl: sodium chloride

Question 6

What is the correct formula for iron(III) sulfate?

Accepted Answer

$$\mathrm{Fe_2$(SO_4$)_3}$$

Question 7

Which of the following elements is a metalloid?

Accepted Answer

Silicon ($$\mathrm{Si})$$

Question 8

Which of the following best explains why sodium forms a $$+1$$ ion and chlorine forms a $$-1$$ ion?

Accepted Answer

Sodium loses one electron to achieve a noble gas configuration, while chlorine gains one electron to achieve a noble gas configuration.

Question 9

Which of the following is the correct Lewis structure for carbon dioxide ($$\mathrm{CO_2$}$$)?

Accepted Answer

O=C=O, with each O atom having two lone pairs

Question 10

Which of the following statements about electromagnetic radiation is correct?

Accepted Answer

As the wavelength increases, the frequency decreases.

Question 11

A photon of light has a wavelength of $$500\ \mathrm{nm}. $$What is its frequency? (Speed of light $$c = 3.00 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$6.00 	imes 10$$^{14}$$\ \mathrm{Hz}$$

Question 12

Which of the following is a property of ionic compounds?

Accepted Answer

They conduct electricity when dissolved in water.

Question 13

Which of the following is the correct orbital diagram for nitrogen ($$Z = 7$$)?

Accepted Answer

1s: $$\uparrow\downarrow 2s$$: $$\uparrow\downarrow 2p$$: $$\uparrow\ \uparrow\ \uparrow$$

Question 14

Which of the following molecules is polar?

Accepted Answer

Ammonia ($$\mathrm{NH_3$})$$

Question 15

Which of the following is the correct name for $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 16

Which of the following best describes the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their valence shell.

Question 17

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 18

Which of the following statements about intermolecular forces is correct?

Accepted Answer

Hydrogen bonds are generally stronger than dipole-dipole interactions.

Question 19

A transition metal forms a compound with the formula $$\mathrm{$$FeCl_3$$}. $$What is the charge on the iron ion in this compound?

Accepted Answer

$$+3$$

Question 20

Which of the following best describes what happens when an electron absorbs energy?

Accepted Answer

The electron moves to a higher energy level (excited state).

Atoms, Elements, and Chemical Bonding: Study Guide for GOB Chemistry

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