Q: A sample contains 2.50 moles of iron. If one mole of iron contains $$6.022 \times 10$$^{23}$$ atoms, how many iron atoms are present in the sample?

$$1.51 \times 10$$^{24}$$ atoms

Q: How many atoms are present in $$0.14$$ mol of calcium ($$\mathrm{Ca}$$)? ($$1$$ mol $$= 6.022 \times 10$$^{23}$$ atoms)

$$8.43 \times 10$$^{22}$$ atoms

Q: Which of the following is the correct formula to calculate the number of atoms in a given number of moles?

$$\text{Number of atoms} = \text{moles} \times 6.022 \times 10$$^{23}$$

Q: If you have 0.5 moles of calcium atoms, how many atoms do you have?

$$3.01 \times 10$$^{23}$$ atoms

Question 1

Which of the following correctly describes the relationship between the atomic number ($$Z$$), mass number ($$A$$), and the number of neutrons ($$n) in an $$atom?

Accepted Answer

$$A = Z + n$$

Question 2

A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many protons, neutrons, and electrons does it have?

Accepted Answer

17 protons, 18 neutrons, 17 electrons

Question 3

Which isotope of Rubidium is more abundant if the atomic mass of Rubidium is 85.4678 amu, given that $$^{85}\mathrm{Rb}$$ has a mass of 84.9117 amu and $$^{87}\mathrm{Rb}$$ has a mass of 86.9095 amu?

Accepted Answer

$$^{85}\mathrm{Rb}$$

Question 4

What is the charge of an ion with 12 protons and 10 electrons?

Accepted Answer

$$+2$$

Question 5

Which of the following is the correct electron configuration for a neutral sodium atom ($$Z=11$$)?

Accepted Answer

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

Question 6

A sample contains 2.50 moles of iron. If one mole of iron contains $$6.022 	imes 10$$^{23}$$ atoms, how many iron atoms are present in the sample?

Accepted Answer

$$1.51 	imes 10$$^{24}$$ atoms

Question 7

How many moles of sodium are present in $$1.376 	imes 10$$^{24}$$ sodium atoms? (1$ mole = 6.022$$ 	imes $$10^{23}$$ atoms)

Accepted Answer

$$2.29$$ moles

Question 8

If you have 6.0 g of magnesium ($$\mathrm{Mg}$$), how many moles of magnesium do you have? ($$\mathrm{Mg}$$ molar mass $$= 24.3 g/$$mol)

Accepted Answer

$$0.247$$ moles

Question 9

A bag of candy has 50 pieces. How many bags are needed to have 250 pieces of candy?

Accepted Answer

5 bags

Question 10

How many atoms are present in $$0.14$$ mol of calcium ($$\mathrm{Ca}$$)? ($$1$$ mol $$= 6.022 	imes 10$$^{23}$$ atoms)

Accepted Answer

$$8.43 	imes 10$$^{22}$$ atoms

Question 11

Which of the following statements about ions is correct?

Accepted Answer

An ion is formed when an atom gains or loses electrons

Question 12

A gold coin has a mass of 197 g. If the molar mass of gold is 197 g/mol, how many moles of gold are present?

Accepted Answer

1 mole

Question 13

Which of the following best explains why isotopes of the same element have different mass numbers?

Accepted Answer

They have different numbers of neutrons

Question 14

If you have 4 bags of candy, each containing 43 pieces, how many pieces of candy do you have in total?

Accepted Answer

172 pieces

Question 15

How many moles of silicon atoms are in $$3.01 	imes 10$$^{23}$$ silicon atoms?

Accepted Answer

$$0.5$$ moles

Question 16

Which of the following is the correct formula to calculate the number of atoms in a given number of moles?

Accepted Answer

$$	ext{Number of atoms} = 	ext{moles} 	imes 6.022 	imes 10$$^{23}$$

Question 17

A sample contains $$1.8 	imes 10$$^{24}$$ atoms of zinc. How many moles of zinc are present?

Accepted Answer

$$2.99$$ moles

Question 18

Which of the following best describes the difference between an atom and an ion?

Accepted Answer

An atom is electrically neutral, while an ion has a net charge

Question 19

If you have 0.5 moles of calcium atoms, how many atoms do you have?

Accepted Answer

$$3.01 	imes 10$$^{23}$$ atoms

Question 20

Which of the following is the correct definition of the atomic number ($$Z$$)?

Accepted Answer

The number of protons in the nucleus of an atom

Atoms, Ions, and Isotopes: General Chemistry Chapter 1 Study Notes

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