Atomic Structure and Chemical Bonding Insights

1. An atom of sulfur has an atomic number of 16 and a mass number of 32. How many neutrons does it have?

16

32

48

14

To find the number of neutrons in an atom, subtract the atomic number from the mass number. The atomic number of sulfur is 16, which represents the number of protons. The mass number is 32, which is the total number of protons and neutrons. Therefore, the number of neutrons can be calculated as follows: 32 (mass number) - 16 (atomic number) = 16 neutrons. This indicates that the sulfur atom has an equal number of neutrons and protons.

Explanation

To find the number of neutrons in an atom, subtract the atomic number from the mass number. The atomic number of sulfur is 16, which represents the number of protons. The mass number is 32, which is the total number of protons and neutrons. Therefore, the number of neutrons can be calculated as follows: 32 (mass number) - 16 (atomic number) = 16 neutrons. This indicates that the sulfur atom has an equal number of neutrons and protons.

2. Which of the following correctly explains why atomic radius increases as you move down a group in the periodic table?

The number of protons decreases, reducing nuclear pull

Additional electron shells are added, pushing the outer electrons farther from the nucleus

Electron repulsion decreases, allowing the atom to expand

The mass number increases, making the atom physically larger

As you move down a group in the periodic table, each successive element has an additional electron shell compared to the one above it. This increase in the number of shells means that the outermost electrons are located farther from the nucleus. Although the number of protons also increases, the effect of added electron shells is more significant, leading to a larger atomic radius. The increased distance between the nucleus and the outer electrons results in a greater atomic size.

Explanation

As you move down a group in the periodic table, each successive element has an additional electron shell compared to the one above it. This increase in the number of shells means that the outermost electrons are located farther from the nucleus. Although the number of protons also increases, the effect of added electron shells is more significant, leading to a larger atomic radius. The increased distance between the nucleus and the outer electrons results in a greater atomic size.

3. Calcium (Ca) has 20 protons and forms an ionic bond with chlorine (Cl). Calcium loses 2 electrons to form Ca²⁺. What is the correct formula and name of the ionic compound formed?

CaCl — calcium chloride

CaCl₂ — calcium chloride

Ca₂Cl — calcium dichloride

CaCl₂ — calcium dichloride

Calcium has a +2 charge after losing two electrons, while each chlorine atom gains one electron to form Cl⁻ ions. To balance the charges, one calcium ion (Ca²⁺) combines with two chloride ions (Cl⁻). This results in the formula CaCl₂, indicating that two chloride ions are needed for every calcium ion to create a neutral compound. The name of this ionic compound is calcium chloride, reflecting the presence of one calcium ion and two chloride ions.

Explanation

Calcium has a +2 charge after losing two electrons, while each chlorine atom gains one electron to form Cl⁻ ions. To balance the charges, one calcium ion (Ca²⁺) combines with two chloride ions (Cl⁻). This results in the formula CaCl₂, indicating that two chloride ions are needed for every calcium ion to create a neutral compound. The name of this ionic compound is calcium chloride, reflecting the presence of one calcium ion and two chloride ions.

4. Match each bonding type with its correct description.

Metallic bonding

Ionic bonding

Covalent bonding

Anion formation

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5. Carbon is described as tetravalent. Which of the following best explains why carbon can form long chains and rings?

Carbon has 4 valence electrons, allowing it to form 4 strong covalent bonds in multiple directions

Carbon has a very large atomic radius, giving it space to bond with many atoms

Carbon is a metal, so it can share electrons freely in a sea of electrons

Carbon has 8 valence electrons, making it already stable and reactive

Carbon's tetravalency, due to its four valence electrons, enables it to form four covalent bonds with other atoms. This property allows carbon to create diverse structures, including long chains and rings, as it can bond in multiple orientations. The ability to form stable single, double, or even triple bonds with itself and other elements facilitates the complexity and versatility of organic molecules, making carbon a fundamental building block of life.

Explanation

Carbon's tetravalency, due to its four valence electrons, enables it to form four covalent bonds with other atoms. This property allows carbon to create diverse structures, including long chains and rings, as it can bond in multiple orientations. The ability to form stable single, double, or even triple bonds with itself and other elements facilitates the complexity and versatility of organic molecules, making carbon a fundamental building block of life.

6. A covalent compound is made of nitrogen and oxygen with two oxygen atoms. Using IUPAC naming conventions, what is the correct name?

Nitrogen oxide

Dinitrogen oxide

Nitrogen dioxide

Nitrogen dioxygen

The compound consists of one nitrogen atom and two oxygen atoms. According to IUPAC naming conventions, the prefix "di-" is used to indicate the presence of two oxygen atoms. Therefore, the name reflects the two oxygen atoms in the formula, leading to "nitrogen dioxide." This name accurately describes the composition of the compound, distinguishing it from other nitrogen oxides that may have different ratios of nitrogen and oxygen.

Explanation

The compound consists of one nitrogen atom and two oxygen atoms. According to IUPAC naming conventions, the prefix "di-" is used to indicate the presence of two oxygen atoms. Therefore, the name reflects the two oxygen atoms in the formula, leading to "nitrogen dioxide." This name accurately describes the composition of the compound, distinguishing it from other nitrogen oxides that may have different ratios of nitrogen and oxygen.

7. The octet rule states that atoms bond to achieve a full outer shell. In the order 2, 8, 8 — an atom with 6 valence electrons will ______ electrons to become stable.

Atoms with 6 valence electrons need to achieve a stable configuration by filling their outer shell, which typically accommodates 8 electrons. To reach this stable state, the atom must gain 2 additional electrons. By doing so, it completes its octet, thereby increasing its stability and fulfilling the octet rule. This behavior is common in nonmetals, which tend to gain electrons during chemical bonding to achieve a full outer shell.

Explanation

Atoms with 6 valence electrons need to achieve a stable configuration by filling their outer shell, which typically accommodates 8 electrons. To reach this stable state, the atom must gain 2 additional electrons. By doing so, it completes its octet, thereby increasing its stability and fulfilling the octet rule. This behavior is common in nonmetals, which tend to gain electrons during chemical bonding to achieve a full outer shell.

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8. Which of the following statements about ionic bonds are correct? Select ALL that apply.

Ionic bonds form between a metal and a non-metal

Ionic compounds use prefixes like mono- and di- in their names

Ionic bonds are brittle and have high melting and boiling points

In ionic bonding, electrons are transferred from one atom to another

Ionic compounds are always negatively charged overall

Ionic bonds typically occur between metals and non-metals, where metals lose electrons and non-metals gain them, resulting in the formation of charged ions. This electron transfer is a defining characteristic of ionic bonding. Additionally, ionic compounds tend to be brittle and exhibit high melting and boiling points due to the strong electrostatic forces between the oppositely charged ions, which require significant energy to break. These properties distinguish ionic compounds from covalent compounds, which often utilize prefixes in their naming conventions.

Explanation

Ionic bonds typically occur between metals and non-metals, where metals lose electrons and non-metals gain them, resulting in the formation of charged ions. This electron transfer is a defining characteristic of ionic bonding. Additionally, ionic compounds tend to be brittle and exhibit high melting and boiling points due to the strong electrostatic forces between the oppositely charged ions, which require significant energy to break. These properties distinguish ionic compounds from covalent compounds, which often utilize prefixes in their naming conventions.

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