CHEM 3300 BWT1 Inorganic Chemistry

Explanation:

Electronic configuration describes how electrons are distributed among the various atomic orbitals of an atom. It reflects the specific arrangement of electrons in shells and subshells, following principles such as the Aufbau principle, Pauli exclusion principle, and Hund’s rule. Understanding an atom’s electronic configuration is essential because it determines the atom’s chemical properties, reactivity, and placement in the periodic table. The configuration does not involve protons or neutrons, nor does it describe the energy levels of the nucleus; it specifically refers to electron distribution in orbitals around the nucleus.

Correct Answer:

The distribution of electrons in atomic orbitals

Why Other Options Are Wrong:

The arrangement of protons in the nucleus. This is incorrect because protons reside in the nucleus, and their arrangement does not define the electronic configuration. Electronic configuration is solely concerned with electrons around the nucleus, not the nucleus itself.

The total number of neutrons in an atom. This is wrong because neutrons are nuclear particles and do not affect the electron arrangement. The electronic configuration focuses exclusively on the electrons in their respective orbitals.

The energy levels of an atom's nucleus. This is incorrect because the energy levels of the nucleus are related to nuclear structure and reactions, not to the distribution of electrons. Electronic configuration deals with energy levels of electrons in atomic orbitals, not the nucleus.

Explanation:

Oxidation is defined as the loss of electrons by an atom, ion, or molecule, which results in an increase in its oxidation state. This is a fundamental concept in redox (reduction-oxidation) reactions, where oxidation always occurs simultaneously with reduction, which is the gain of electrons. Oxidation is not about the formation of ionic bonds or proton transfer; it specifically involves changes in electron count and oxidation number.

Correct Answer:

A loss of electrons resulting in an increase in oxidation state

Why Other Options Are Wrong:

A gain of electrons leading to a decrease in oxidation state. This is incorrect because gaining electrons is reduction, not oxidation.

The formation of ionic bonds between elements. This is wrong because ionic bond formation is a type of chemical bonding, not the definition of oxidation.

The transfer of protons between reactants. This is incorrect because oxidation deals with electrons, not protons.

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.

Explanation:

The tendency of an atom to lose electrons and form a cation is directly related to its metallic character. Metals have low ionization energies, meaning they can easily lose electrons to form positive ions. Therefore, the metallic characteristic reflects the ease with which an atom loses electrons. Ionization energy is also related, but the metallic character more broadly describes the general chemical behavior of elements, including their cation-forming tendency.

Correct Answer:

Metallic Characteristic

Why Other Options Are Wrong:

Atomic Radius. This is incorrect because atomic radius indicates the size of an atom, not directly its tendency to lose electrons, although larger atoms tend to lose electrons more easily.

Ionization Energy. While related, this is a quantitative measure of energy required to remove an electron, not the broader periodic trend indicating cation formation tendency.

Electronegativity. This is wrong because electronegativity measures an atom's ability to attract electrons, not to lose them.Electron Affinity. This is incorrect because electron affinity describes the energy change when an atom gains an electron, the opposite of losing one.

Non-metallic Characteristic. This is wrong because non-metals tend to gain electrons to form anions, not lose electrons to form cations.

Explanation:

Balancing redox reactions is essential to satisfy the conservation of mass and charge. In a redox reaction, electrons are transferred from one species to another. Balancing ensures that the number of electrons lost in oxidation equals the number of electrons gained in reduction, and that the total number of atoms of each element is the same on both sides of the equation. This allows the reaction to accurately reflect the stoichiometry and charge balance. The other options are unrelated to the primary purpose of balancing redox reactions.

Correct Answer:

To maintain the conservation of mass and charge

Why Other Options Are Wrong:

To ensure that the total number of atoms is equal on both sides. While partially true, this only addresses mass balance and ignores charge balance, which is crucial in redox reactions.

To determine the reaction rate. This is incorrect because balancing does not provide information about how fast the reaction occurs.

To identify the limiting reagent. This is false; balancing the equation does not directly determine the limiting reagent, which depends on the amounts of reactants present.

Explanation:

Oxidation states are formal charges assigned to atoms in a compound that indicate the hypothetical number of electrons an atom has gained, lost, or shared relative to its elemental state. Chemists follow a set of systematic rules to determine these states, considering factors such as known oxidation numbers of elements, the electronegativity differences between atoms, and the types of bonds formed. The key is that these are rules-based assignments rather than direct physical measurements like counting protons or valence electrons. This ensures consistent interpretation of redox reactions and electron distribution in compounds.

Correct Answer:

Oxidation states are assigned according to a set of rules that account for the gain, loss, or sharing of electrons in a compound.

Why Other Options Are Wrong:

Oxidation states are assigned based on the total number of protons in the nucleus of an atom. This is incorrect because oxidation states have nothing to do with the number of protons. They are related to the electron distribution in chemical bonding, not nuclear properties.

Oxidation states are determined by the number of electrons an atom has in its outermost shell. This is wrong because the oxidation state can differ from the actual valence electrons, especially in molecules where electrons are shared or transferred. It is a formalism, not a direct count of valence electrons.

Oxidation states are calculated by considering the electronegativity of the atoms and the type of bonds formed. While electronegativity influences bond polarity and can inform oxidation states, this option is incomplete. Oxidation states are formally assigned using a set of explicit rules, not just by considering electronegativity and bond type.

Explanation:

The Aufbau Principle states that electrons occupy orbitals starting from the lowest energy level and proceed to higher energy levels in order to minimize the atom's total energy. This systematic filling determines the ground-state electron configuration of elements. Electrons do not fill orbitals randomly or in decreasing energy order, and they do not all occupy orbitals of the same energy at the same time (that principle is related to Hund's Rule).

Correct Answer:

Electrons fill orbitals in order of increasing orbital energy

Why Other Options Are Wrong:

Electrons fill orbitals in order of decreasing orbital energy. This is incorrect because the filling begins with the lowest energy orbitals, not the highest.

Electrons fill orbitals with the same energy simultaneously. This is false; Hund’s Rule governs the filling of orbitals with the same energy, not the Aufbau Principle.

Electrons fill orbitals randomly. This is incorrect because electron filling follows a specific order based on energy levels, not randomness.

Explanation:

The Earth’s crust is primarily composed of silicate minerals, which are compounds of silicon and oxygen, often combined with aluminum and iron. Silicon and oxygen form the basic framework of most minerals, while aluminum and iron are common cations in these structures. Helium, sulfur, carbon, and zinc are either rare or not significant components of the crust, making the second option the correct description of the major elemental composition.

Correct Answer:

silicon, oxygen aluminum, and iron

Why Other Options Are Wrong:

helium, oxygen, and aluminum. This is incorrect because helium is a noble gas present in trace amounts and does not form minerals; it is not a significant crustal element.

sulfur, oxygen, iron, and magnesium. This is wrong because although sulfur, iron, and magnesium are present in some minerals, they are not the primary elements in the majority of Earth's crust minerals.

silicon, oxygen carbon, and zinc. This is false because carbon and zinc are minor components; carbon is mainly in organic matter or carbonates, and zinc occurs in trace amounts, not as major crustal elements.

Explanation:

Metals are elements that typically exhibit excellent conductivity of heat and electricity due to the presence of free-moving valence electrons. They are usually hard and have a shiny (lustrous) appearance. Additionally, metals are malleable, meaning they can be hammered into sheets, and ductile, meaning they can be drawn into wires. These physical and chemical properties distinguish metals from metalloids, nonmetals, and halogens, which do not generally exhibit this full set of metallic characteristics.

Correct Answer:

Metals

Why Other Options Are Wrong:

Metalloids. This is incorrect because metalloids have properties intermediate between metals and nonmetals. While some may conduct electricity, they are not generally as good conductors as metals, nor do they consistently exhibit malleability or ductility.

Nonmetals. This is wrong because nonmetals are poor conductors of heat and electricity, often brittle in solid form, and lack metallic luster. They do not display the characteristic malleability or ductility of metals.

Halogens. This is incorrect because halogens are nonmetals that exist as reactive elements and do not have metallic properties such as conductivity, luster, malleability, or ductility. Their chemical behavior is dominated by high reactivity and electron affinity, not metallic characteristics.