CHEM 3300 BWT1 Inorganic Chemistry

Explanation:

Oxidation refers to the loss of electrons by an atom or ion, which results in an increase in its oxidation state. When an element loses electrons, it becomes more positively charged, reflecting a higher oxidation number. Conversely, reduction involves gaining electrons and a decrease in oxidation state. Therefore, in an oxidation process, the element’s oxidation state rises as it loses electrons. This is a fundamental principle in redox chemistry and is essential for identifying which species is oxidized or reduced in a chemical reaction.

Correct Answer:

goes up and the element loses electrons.

Why Other Options Are Wrong:

goes up and the element gains electrons. This is incorrect because gaining electrons corresponds to reduction, not oxidation. Oxidation always involves electron loss, not gain.

goes down and the element loses electrons. This is wrong because losing electrons increases the oxidation state, not decreases it. A decrease in oxidation state indicates reduction, not oxidation.

goes down and the element gains electrons. This is incorrect because this describes reduction. During reduction, an element gains electrons and its oxidation state decreases, which is the opposite of what occurs in oxidation.

Explanation:

Ionic compounds form crystal lattice structures in which larger anions create a framework, and smaller cations fit into the spaces (interstices) between them. This arrangement maximizes electrostatic attraction while minimizing repulsion, creating a stable, repeating lattice structure. The other options are incorrect because electrons are not considered part of the lattice framework, and cations do not generally form the larger framework in ionic solids.

Correct Answer:

anions; cations

Why Other Options Are Wrong:

anions; electrons. This is incorrect because electrons are not fixed in the lattice; they are shared or transferred but do not occupy the interstitial positions as ions.

cations; anions. This is wrong because cations are smaller and fit into the spaces between larger anions; they do not form the main lattice framework.

cations; electrons. This is false because electrons are not part of the crystal packing in ionic compounds, and cations alone do not form the primary lattice.

Explanation:

The formal charge is calculated using the valence electrons minus the sum of non-bonding electrons and half of the bonding electrons. This reflects how many electrons an atom “owns” in a molecule relative to its neutral state. Using the full bonding electrons without dividing by two, or reversing the subtraction, leads to incorrect formal charges. Therefore, the correct formula is Formal Charge = Valence Electrons - (Non-bonding Electrons + 1/2 Bonding Electrons).

Correct Answer:

Formal Charge = Valence Electrons - (Non-bonding Electrons + 1/2 Bonding Electrons)

Why Other Options Are Wrong:

Formal Charge = Valence Electrons - (Non-bonding Electrons + Bonding Electrons). This is incorrect because it subtracts all bonding electrons instead of dividing them equally between two atoms, which overestimates the electrons “owned” by the atom.

Formal Charge = Non-bonding Electrons + 1/2 Bonding Electrons - Valence Electrons. This is false because it reverses the formula; the valence electrons should be the starting point, not subtracted last.

Formal Charge = Non-bonding Electrons - (Valence Electrons + 1/2 Bonding Electrons). This is incorrect because it misplaces the subtraction and ignores the correct allocation of bonding electrons, giving an invalid formal charge.

Explanation:

Ionic bonds result from the transfer of electrons from a metal to a nonmetal, creating oppositely charged ions held together by electrostatic attraction. Covalent bonds, in contrast, involve the sharing of electrons between nonmetals. This fundamental difference in electron behavior distinguishes the two bond types. The other options are incorrect because they mischaracterize the elements involved, solubility, or the nature of charges.

Correct Answer:

Ionic bonds hold together oppositely charged atoms, whereas covalent bonds hold together atoms that share electrons

Why Other Options Are Wrong:

Ionic bonds form between the same two elements, whereas covalent bonds form between different elements. This is false; ionic bonds typically form between metals and nonmetals, not between the same elements.

Ionic bonds hold together compounds that do not dissolve in water, whereas covalent bonds hold together molecules that dissolve in water. This is incorrect because solubility varies widely and is not a defining feature of bond type.

Ionic bonds consist of atoms with partial charges, whereas covalent bonds consist of atoms with full positive and negative charges. This is misleading; ionic bonds involve full charges (cation and anion), while covalent bonds may have partial charges in polar molecules.

Explanation:

Primary chemical bonds include ionic, covalent, and metallic bonds, which involve the actual formation of stable electron interactions that hold atoms together in compounds or metals. A hydrogen bond, on the other hand, is considered a secondary or intermolecular force. It is weaker than primary bonds and occurs between molecules rather than within a molecule or lattice. Therefore, hydrogen bonding is an exception when listing primary bonding types.

Correct Answer:

Hydrogen bond

Why Other Options Are Wrong:

Ionic bond. This is incorrect because ionic bonding is a primary bond formed by the electrostatic attraction between cations and anions.

Metallic bond. This is wrong because metallic bonding is a primary bond, characterized by the attraction between metal cations and delocalized electrons in a lattice.

Covalent bond. This is incorrect because covalent bonding is a primary bond formed through the sharing of electrons between atoms.

Explanation:

Non-metals are typically poor conductors of heat and electricity, not ductile or malleable, often have a dull appearance, and many exist as gases at room temperature. However, stating that non-metals have 3 valence electrons is not universally correct. Non-metals can have varying numbers of valence electrons, typically ranging from 1 to 7 depending on the group in the periodic table. Therefore, the statement about having 3 valence electrons does not accurately describe all non-metals.

Correct Answer:

have 3 valence electrons

Why Other Options Are Wrong:

poor conductors of heat and electricity. This is incorrect as an answer because it is a true property of non-metals. Non-metals generally lack free electrons and do not conduct heat or electricity efficiently.

not ductile or malleable. This is wrong because it accurately describes non-metals, which are brittle rather than ductile or malleable.

dull. This is incorrect because many non-metals have a dull appearance, unlike metals which are lustrous.

many non-metals are gases. This is wrong because it is true; a significant number of non-metals, including oxygen, nitrogen, and chlorine, exist as gases at room temperature.

Explanation:

Electronegativity decreases as you move from the top to the bottom of a group in the periodic table because atoms lower in a group have more electron shells, increasing the distance between the nucleus and the valence electrons. This increased distance reduces the nucleus’s ability to attract bonding electrons. This trend is a well-documented periodic trend, along with other trends such as atomic radius, ionization energy, and metallic character, which vary systematically across periods and down groups.

Correct Answer:

A decrease in electronegativity as you move from top to bottom in a group

Why Other Options Are Wrong:

A consistent increase in atomic mass from left to right. This is incorrect because atomic mass does not increase consistently across a period; it generally increases but has irregularities due to isotopes and variations in elemental composition.

A gradual decrease in ionization energy down a group. While ionization energy does decrease down a group, the question asks for a trend “observed,” and electronegativity is a more directly measurable chemical property commonly referenced in periodic trends.

A uniform increase in metallic character across a period. This is wrong because metallic character actually decreases across a period from left to right, as elements become less metallic and more non-metallic in nature.

Explanation:

Lone pairs of electrons occupy space around a central atom and repel bonded electron groups, which affects the overall shape of the molecule. This is predicted by VSEPR theory, which states that electron pairs (bonding and nonbonding) arrange themselves to minimize repulsion. Lone pairs can compress bond angles, changing the molecular shape, even if the electron geometry remains the same.

Correct Answer:

They push away the bonded electron groups

Why Other Options Are Wrong:

They give room for bonded atoms to spread out. This is misleading; lone pairs do not provide space for atoms—they occupy space themselves and push bonded atoms closer together.

They change the atom's electron geometry. This is incorrect; lone pairs affect molecular geometry, not the overall electron geometry, which considers all electron groups.

They have no effect on the shape. This is false because lone pairs create repulsion that alters bond angles and the molecular shape.

Explanation:

A hydride ion (H⁻) is a negatively charged hydrogen atom with an extra electron, making it highly nucleophilic and strongly basic. It readily donates its lone pair of electrons to electrophiles in chemical reactions. Its basicity arises from its tendency to accept a proton, and its nucleophilicity comes from the availability of its lone electron pair. Hydride ions are not acidic because they do not readily donate a proton.

Correct Answer:

a strong basic nucleophile

Why Other Options Are Wrong:

a strong acidic nucleophile. This is incorrect because hydride ions do not donate protons and thus are not acidic; they are electron-rich.

a weak basic nucleophile. This is wrong because hydride ions are highly basic due to their negative charge and strongly nucleophilic, not weak.

a weak acidic nucleophile. This is incorrect because hydride ions are neither acidic nor weak; they are strongly basic and nucleophilic.