Chemistry 101 – Inorganic & Physical Chemistry (Lecture 1-68)

What two characteristics define matter?

Matter occupies space and has mass.

How is a substance different from a mixture?

A substance has constant composition and distinct properties, whereas a mixture contains two or more substances that retain their identities.

Define homogeneous mixture.

A mixture whose composition is uniform throughout.

What is an element?

A substance that cannot be separated into simpler substances by chemical means.

Define compound.

A substance composed of atoms of two or more elements chemically united in fixed proportions.

Which methods separate mixtures into pure substances?

Physical methods (e.g., filtration, distillation).

Which methods separate compounds into elements?

Chemical methods (e.g., electrolysis).

Name the three classical states of matter.

Solid, liquid, and gas.

How do gases differ from liquids and solids on a molecular level?

Gas molecules are much farther apart than those in liquids and solids.

Give the term for a solid turning directly into a gas.

Sublimation.

What is the reverse of sublimation?

Deposition (gas → solid).

Define physical property.

A property that can be measured without changing the substance’s composition.

Define chemical property.

A property observed when a substance undergoes a chemical change.

Differentiate extensive and intensive properties with an example of each.

Extensive depends on amount (mass); intensive does not (density).

List the seven SI base quantities with their units.

Length-meter (m), Mass-kilogram (kg), Time-second (s), Temperature-kelvin (K), Amount-mole (mol), Electric current-ampere (A), Luminous intensity-candela (cd).

What prefix represents 10⁶?

Mega- (M).

Convert 1 dm³ to liters.

1 dm³ = 1 L.

Write the density equation.

Density = mass / volume.

Common density units for solids and liquids?

g cm⁻³ or g mL⁻¹.

Give the formula to convert °C to K.

K = °C + 273.15.

Express 0.00000772 in scientific notation.

7.72 × 10⁻⁶.

State Dalton’s first postulate of atomic theory.

Elements are composed of extremely small particles called atoms.

Which subatomic particles reside in the nucleus?

Protons and neutrons.

Define atomic number (Z).

The number of protons in an atom’s nucleus (equals electrons in a neutral atom).

Define mass number (A).

Total number of protons plus neutrons in the nucleus.

What are isotopes?

Atoms of the same element (same Z) with different mass numbers (A).

Give three naturally occurring diatomic elements besides H₂.

N₂, O₂, F₂ (also Cl₂, Br₂, I₂).

Differentiate cation and anion.

Cation is positively charged (loss of electrons); anion is negatively charged (gain of electrons).

Define polyatomic ion and give an example.

An ion containing more than one atom, e.g., OH⁻, NH₄⁺.

How many electrons can an s subshell hold?

2 electrons.

Maximum electrons in a p subshell?

6 electrons.

State the Aufbau principle.

Electrons fill the lowest-energy orbitals available first.

What does Hund’s rule state?

Electrons occupy degenerate orbitals singly with parallel spins before pairing.

State the Pauli exclusion principle.

No two electrons in the same atom can have identical sets of four quantum numbers.

Give the four quantum numbers and what each describes.

n-principal energy level; ℓ-subshell shape; mℓ-orbital orientation; ms-electron spin.

Which block of the periodic table contains transition metals?

The d-block.

Group 1A elements are called?

Alkali metals.

Define atomic radius trend across a period.

Atomic radius decreases from left to right.

What is ionization energy?

Minimum energy required to remove an electron from a gaseous atom in its ground state.

Which family has the highest electron affinities?

Halogens (Group 7A).

Describe an ionic bond.

Electrostatic attraction resulting from complete electron transfer between a metal and a non-metal.

Describe a covalent bond.

Bond formed by sharing of electron pairs between atoms.

List three differences between ionic and covalent compounds regarding physical state and melting point.

Ionic: crystalline solids, high melting/boiling, brittle. Covalent: often gases/liquids, low melting/boiling, softer.

What model predicts molecular shapes using electron pair repulsion?

VSEPR (Valence-Shell Electron Pair Repulsion) model.

According to VSEPR, what geometry does AB₂ with no lone pairs adopt?

Linear.

What is the geometry of an AB₄ molecule with no lone pairs?

Tetrahedral.

Give the shape of an AB₃E molecule.

Trigonal pyramidal.

What hybridization corresponds to a tetrahedral arrangement?

sp³.

Which hybridization leads to trigonal planar geometry?

sp².

Hybridization for a linear BeCl₂ molecule?

sp.

Write Avogadro’s number.

6.022 × 10²³ entities per mole.

Formula to calculate moles from mass.

n = mass (g) / molar mass (g mol⁻¹).

Define molecular mass.

Sum of atomic masses in a molecular formula (amu or g mol⁻¹).

Give the percent composition formula.

% element = (n × molar mass of element / molar mass of compound) × 100%.

What is a limiting reagent?

Reactant that is completely consumed first, limiting product formed.

Define theoretical yield.

Maximum amount of product predicted from stoichiometry assuming complete conversion.

Percent yield equation.

(actual yield / theoretical yield) × 100%.

Define solution.

Homogeneous mixture of two or more substances.

Differentiate saturated and unsaturated solutions.

Saturated holds maximum solute at a given T; unsaturated holds less than maximum.

Define supersaturated solution.

Contains more solute than the saturated amount at that temperature.

State ‘like dissolves like’.

Substances with similar intermolecular forces are mutually soluble.

What is molarity (M)?

Moles of solute per liter of solution.

Define molality (m).

Moles of solute per kilogram of solvent.

Write the expression for mole fraction (Xᵢ).

Xᵢ = nᵢ / n_total (dimensionless).

Arrhenius definition of acid.

Substance that ionizes in water to produce H⁺ ions.

Arrhenius definition of base.

Substance that ionizes in water to produce OH⁻ ions.

Brønsted–Lowry acid and base definitions.

Acid = proton donor; Base = proton acceptor.

Define amphoteric substance with an example.

Can act as acid or base; water (H₂O) is amphoteric.

Lewis acid definition.

Electron-pair acceptor.

Write the ion-product constant of water at 25 °C.

K_w = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴.

Relationship between pH and [H⁺].

pH = −log[H⁺].

What pH indicates neutrality at 25 °C?

pH = 7.

Express pOH in terms of OH⁻ concentration.

pOH = −log[OH⁻].

Relationship between pH and pOH at 25 °C.

pH + pOH = 14.

Define buffer solution.

Solution of a weak acid/base and its conjugate salt that resists pH changes upon small additions of acid or base.

State Boyle’s law in words.

For a fixed amount of gas at constant T, pressure is inversely proportional to volume.

Write Charles’s law equation.

V ∝ T (at constant P and n) or V₁/T₁ = V₂/T₂.

State Avogadro’s law.

At