Q: Which of the following is the correct formula for calculating the charge of an ion?

$$\text{charge} = \#\text{protons} - \#\text{electrons}$$

Q: A sample of chlorine contains 75% $$\mathrm{^{35}Cl} ($$mass = 35 amu) and 25% $$\mathrm{^{37}Cl} ($$mass = 37 amu). What is the atomic mass of chlorine?

$$(0.75 \times 35) + (0.25 \times 37) = 35.5$$ amu

Question 1

Which statement best describes John Dalton's atomic theory as it relates to chemical reactions?

Accepted Answer

Atoms of different elements combine in whole-number ratios to form compounds.

Question 2

Which subatomic particle determines the identity of an element and is also known as the atomic number ($$Z$$)?

Accepted Answer

Proton

Question 3

A neutral atom of sodium ($$\mathrm{Na}) $$has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 4

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of protons and electrons.

Question 5

A chlorine atom has 17 protons, 18 neutrons, and 17 electrons. What is the correct isotope notation for this atom?

Accepted Answer

$$\mathrm{^{35}Cl}$$

Question 6

Which of the following statements about the nucleus of an atom is correct?

Accepted Answer

The nucleus contains protons and neutrons and is very dense.

Question 7

If a neutral atom of magnesium ($$\mathrm{Mg}) $$loses two electrons, what is the resulting ion and its charge?

Accepted Answer

$$\mathrm{Mg$$^{2+}$$}$$ ion

Question 8

Which of the following best describes a property of metals compared to nonmetals?

Accepted Answer

Metals are malleable and good conductors of electricity.

Question 9

Which group on the periodic table contains elements that are very unreactive due to a full outer electron shell?

Accepted Answer

Noble gases (Group 8A)

Question 10

A fluorine atom ($$\mathrm{F}) $$has 9 protons and 9 electrons. If it gains one electron, what is the charge of the resulting ion?

Accepted Answer

$$1-$$

Question 11

Which of the following best describes a polyatomic ion?

Accepted Answer

A group of atoms bonded together that carries a net charge.

Question 12

Which of the following is the correct formula for calculating the charge of an ion?

Accepted Answer

$$	ext{charge} = \#	ext{protons} - \#	ext{electrons}$$

Question 13

Which of the following best explains why the periodic table is organized by atomic number rather than atomic mass?

Accepted Answer

Atomic number determines the chemical properties of an element.

Question 14

A sample of chlorine contains 75% $$\mathrm{^{35}Cl} ($$mass = 35 amu) and 25% $$\mathrm{^{37}Cl} ($$mass = 37 amu). What is the atomic mass of chlorine?

Accepted Answer

$$(0.75 	imes 35) + (0.25 	imes 37) = 35.5$$ amu

Question 15

Which of the following is a property of transition elements compared to main group elements?

Accepted Answer

Their properties are less predictable and often involve unfilled d orbitals.

Question 16

Which of the following best describes a metalloid?

Accepted Answer

An element that exhibits properties of both metals and nonmetals.

Question 17

Which of the following is the correct way to write the symbol for an ion of sulfur with a $$2-$$ charge?

Accepted Answer

$$\mathrm{S$$^{2-}$$}$$

Question 18

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 19

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have a full outer shell of electrons.

Question 20

Which of the following is the best analogy for the structure of the atom as described in the study materials?

Accepted Answer

The nucleus is like the sun and the electrons are like the planets orbiting it.

Atoms and Elements: Foundations of Chemistry

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