$$1.20 \times 10$$^{24}$$ atoms

$$\text{Average Atomic Mass} = \sum (\text{Fractional abundance} \times \text{isotope exact mass})$$

$$6.022 \times 10$$^{23}$$ particles per mole

Question 1

Which of the following statements best describes isotopes of an element?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 2

An atom of magnesium has 12 protons, 12 neutrons, and 12 electrons. What is its mass number?

Accepted Answer

$$24$$

Question 3

Which group on the periodic table contains the most reactive metals?

Accepted Answer

Group 1A (alkali metals)

Question 4

What is the average atomic mass of an element with the following isotopes: 60.0% $$^{63}Cu (62.93 $$amu) and 40.0% $$^{65}Cu (64.93 $$amu)?

Accepted Answer

$$63.73$$ amu

Question 5

Which of the following best describes the relationship between atomic number and the periodic table?

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 6

How many atoms are present in 2.00 moles of silver ($$Ag$$)? Use Avogadro's number.

Accepted Answer

$$1.20 	imes 10$$^{24}$$ atoms

Question 7

A sample contains $$3.01 	imes 10$$^{22}$$ atoms of gold. How many moles of gold does it contain?

Accepted Answer

$$0.05$$ moles

Question 8

Which of the following is the correct formula for calculating the average atomic mass of an element?

Accepted Answer

$$	ext{Average Atomic Mass} = \sum (	ext{Fractional abundance} 	imes 	ext{isotope exact mass})$$

Question 9

Which group on the periodic table contains elements that are generally unreactive and exist as gases at room temperature?

Accepted Answer

Group 8A (noble gases)

Question 10

If you have 12.0 grams of carbon ($$C$$), how many moles of carbon do you have? (Atomic mass of $$C = 12.01 g/$$mol)

Accepted Answer

$$1.00$$ mole

Question 11

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical and physical properties.

Question 12

A chlorine atom has 17 protons, 18 neutrons, and 17 electrons. What is its mass number?

Accepted Answer

$$35$$

Question 13

Which of the following best describes Avogadro's number?

Accepted Answer

$$6.022 	imes 10$$^{23}$$ particles per mole

Question 14

How many protons, neutrons, and electrons are in a neutral atom of $$^{23}Na$$?

Accepted Answer

11 protons, 12 neutrons, 11 electrons

Question 15

Which of the following elements is a halogen?

Accepted Answer

Chlorine

Question 16

A sample of magnesium contains 3.01 grams. How many moles of magnesium are present? (Atomic mass of $$Mg = 24.31 g/$$mol)

Accepted Answer

$$0.124$$ moles

Question 17

Which of the following best explains why elements in the same group have similar properties?

Accepted Answer

They have the same number of valence electrons.

Question 18

If a silver ring contains $$2.80 	imes 10$$^{22}$$ silver atoms, how many moles of silver does it contain?

Accepted Answer

$$0.0465$$ moles

Question 19

Which of the following is the correct definition of molar mass?

Accepted Answer

The mass in grams of 1 mole of substance.

Question 20

Which of the following is a property of alkali metals?

Accepted Answer

They react vigorously with water.

Atoms, Isotopes, the Periodic Table, and the Mole: Foundational Concepts in General Chemistry

Study Guide - Practice Questions