PAP Chemistry 1st Semester Review

This set of flashcards covers key concepts in chemistry, including definitions of matter, properties, types of changes, and classifications of matter.

What is chemistry the study of?

The study of the composition of matter and all of the changes that matter undergoes.

Define matter.

Matter is anything that has mass and occupies a space.

What are the 5 phases of matter?

1. Solid, 2. Liquid, 3. Gas, 4. Plasma, 5. Bose-Einstein Condensate.

What is a solid?

A phase of matter where atoms/molecules are tightly packed, have definite shape and volume, high density, expand slightly when heated.

What defines a liquid?

A phase of matter with tightly packed atoms/molecules that are mobile, having definite volume but taking the shape of the container.

Describe gas as a phase of matter.

A phase where atoms/molecules are not tightly packed, have no definite shape or volume, and can be easily compressed.

What is plasma?

A gas composed of positive ions surrounded by electrons, occurring at very high temperatures.

Define metals in the context of matter classification.

Metals are elements located on the left side of the periodic table, exhibiting properties like luster, malleability, and good conductivity.

Differentiate between a compound and a mixture.

A compound is a substance formed from two or more elements chemically combined in a definite ratio, while a mixture can vary in composition.

What is a physical property?

A quality or condition of a substance that can be observed or measured without changing its composition.

Explain a chemical property.

The ability of a substance to undergo chemical reactions and form new substances.

What is a physical change?

A change that alters a substance without changing its composition.

List four indicators of a chemical reaction.

Change in color, temperature, odor, or formation of a precipitate.

What are intensive and extensive properties?

Intensive properties do not depend on the amount of substance, while extensive properties do.

What is the formula for density?

Density equals mass divided by volume (D = M/V).

What is the significance of Avogadro’s number?

It is 6.022 x 10^23, representing the number of atoms or molecules in one mole of any substance.

Identify the three main particles in an atom.

Protons (+1 charge, mass = 1.0078 amu), Neutrons (0 charge, mass = 1.00866 amu), Electrons (-1 charge, mass = 5.486 x 10^-4 amu).

What occurs during beta decay?

The transformation of a neutron into a proton with the emission of an electron.

How is nuclear fission defined?

The splitting of an atom into smaller atoms.

What does E=mc^2 represent?

E is energy, m is mass, and c is the speed of light.

What does the term 'binding energy' mean?

The energy required to hold a nucleus together.

Describe what happens to electrons in ionic bonding.

Electrons are transferred from one atom to another.

What are properties of ionic compounds?

High melting points, do not conduct electricity in solid form, brittle, and many are soluble in water.

What do we mean when we say water is 'polar'?

Water has a partially positive end and a partially negative end due to uneven sharing of electrons.

Define valence electrons.

Electrons in the outermost energy level.

What is ionization energy?

The energy needed to remove an electron from a neutral atom or ion.

Explain the difference between accuracy and precision.

Accuracy measures how close a value is to the true value, while precision measures how repeatable measurements are.

What will happen to the atomic radius as you move across the periodic table from left to right?

The atomic radius decreases due to increased nuclear charge pulling the electron cloud closer.

What is the measurement for molar mass?

The mass of one mole of a substance, typically expressed in grams per mole (g/mol).

What are isotopes?

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Define the atomic number (Z).

The number of protons found in the nucleus of an atom, uniquely identifying the element.

What is the mass number (A)?

The total number of protons and neutrons in an atomic nucleus.

Describe alpha decay.

A type of radioactive decay in which an atomic nucleus emits an alpha particle, which consists of two protons and two neutrons (^{4}_{2}He).

What is nuclear fusion?

The process of combining two light atomic nuclei to form a single heavier one while releasing massive amounts of energy.

Define covalent bonding.

A type of chemical bond that involves the sharing of electron pairs between atoms.

What is electronegativity?

A measure of the ability of an atom in a chemical compound to attract electrons.

State the Law of Conservation of Mass.

The principle that mass is neither created nor destroyed in a chemical reaction; the total mass of the reactants equals the total mass of the products.

What is half-life (t_{1/2})?

The time required for one-half of the nuclei of a radioisotope sample to decay to its products.

Explain metallic bonding.

The chemical bonding that results from the attraction between metal atoms and the surrounding sea of mobile electrons.

What is the difference between a homogeneous and a heterogeneous mixture?

A homogeneous mixture has a uniform composition throughout, such as salt water, whereas a heterogeneous mixture has a non-uniform composition with distinct phases, such as salad or sand in water.

Define a Bose-Einstein Condensate.

A state of matter formed at temperatures approaching absolute zero (0 K), where atoms lose their individual identity and collapse into a single quantum state, behaving as a "super-atom."

What are the horizontal rows and vertical columns of the periodic table called?

The horizontal rows are called periods, and the vertical columns are called groups or families.

What is an alloy?

A solid solution or mixture of two or more elements, where at least one is a metal, created to enhance properties like strength or corrosion resistance.

Explain the difference between a cation and an anion.

A cation is a positively charged ion formed when an atom loses electrons, while an anion is a negatively charged ion formed when an atom gains electrons.

What is the molar volume of a gas at Standard Temperature and Pressure (STP)?

One mole of any ideal gas occupies a volume of 22.4 L at a temperature of 273.15 K (0^{\circ}C) and a pressure of 1 atm.

Define a polyatomic ion.

A group of covalently bonded atoms that carries a net electric charge and acts as a single unit in chemical reactions.

Differentiate between exothermic and endothermic processes.

Exothermic processes release energy to the surroundings (usually as heat), while endothermic processes absorb energy from the surroundings.

What is the Octet Rule?

The tendency of atoms to prefer to have 8 electrons in their valence shell, which provides the same stable electron configuration as a noble gas.

Describe a Lewis dot structure.

A structural representation that uses dots to show the valence electrons of an atom and how they are shared or paired within a molecule.

What is molarity?

A measure of the concentration of a solute in a solution, expressed as moles of solute per liter of solution (M = mol/L).

Define the Kinetic Molecular Theory of Gases.

A model describing gas as particles in constant, rapid, random motion, where collisions are perfectly elastic and particle volume is negligible compared to the container volume.

What is the Ideal Gas Law formula?

PV = nRT, where P is pressure, V is volume, n is number of moles, R is the ideal gas constant, and T is temperature in Kelvin.

Define a Brønsted-Lowry acid.

A substance that acts as a proton (H^{+}) donor in a chemical reaction.

Define a Brønsted-Lowry base.

A substance that acts as a proton (H^{+}) acceptor in a chemical reaction.

What is the pH scale?

A logarithmic scale used to specify the acidity or basicity of an aqueous solution, typically ranging from 0 to 14, with 7 being neutral.

Differentiate between an empirical and a molecular formula.

An empirical formula shows the simplest whole-number ratio of atoms in a compound, while a molecular formula shows the actual number of atoms of each element in a molecule.

What is activation energy (E_{a})?

The minimum amount of energy that must be provided to compounds to result in a chemical reaction.

Define a catalyst.

A substance that increases the rate of a chemical reaction by lowering the activation energy without being consumed in the process.

What is a limiting reactant?

The reactant that is entirely consumed first in a chemical reaction, limiting the total amount of product that can be formed.

What is the Law of Definite Proportions?

The law stating that a specific chemical compound always contains its component elements in a fixed ratio by mass, regardless of the sample size or source.

Define specific heat capacity.

The amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius (or one Kelvin), typically measured in J/(g \cdot ^{\circ}C).

What are the phase changes of sublimation and deposition?

Sublimation is the process of a solid changing directly into a gas, while deposition is the process of a gas changing directly into a solid.

Identify the names for Groups 1, 2, 17, and 18 on the periodic table.

Group 1: Alkali Metals; Group 2: Alkaline Earth Metals; Group 17: Halogens; Group 18: Noble Gases.

What does VSEPR theory predict?

Valence Shell Electron Pair Repulsion (VSEPR) theory predicts the three-dimensional geometric shapes of molecules based on the repulsion between valence electron pairs surrounding a central atom.

Define intermolecular forces (IMFs).

The attractive or repulsive forces between neighboring particles (atoms, molecules, or ions), such as London dispersion forces, dipole-dipole interactions, and hydrogen bonding.

How is percent yield calculated?

It is calculated by finding the ratio of the actual yield to the theoretical yield: Percent\ Yield = (Actual / Theoretical) \times 100\%.

What is a saturated solution?

A solution that contains the maximum amount of dissolved solute possible at a given temperature and pressure.

Define stoichiometry.

The study of the quantitative relationships and ratios between reactants and products in a chemical reaction based on a balanced equation.

List the five primary types of chemical reactions.

Synthesis, decomposition, single-replacement, double-replacement, and combustion.

What is a precipitate?

An insoluble solid that emerges from a liquid solution during a chemical reaction, often as one of the four indicators of a chemical change.

Define absolute zero.

The lowest possible temperature, defined as 0 K or -273.15^{\circ}C, where atoms possess minimum thermal motion and a Bose-Einstein Condensate can form.

Differentiate between theoretical yield and actual yield.

Theoretical yield is the calculated maximum amount of product possible from a reaction, whereas actual yield is the amount of product truly obtained in an experiment.

What is a salt in chemistry?

An ionic compound produced from the neutralization reaction of an acid and a base, consisting of a cation from the base and an anion from the acid.

State Boyle's Law.

A gas law stating that the pressure and volume of a gas are inversely proportional at a constant temperature: P{1}V{1} = P{2}V{2}.

State Charles's Law.

A gas law stating that the volume and absolute temperature of a gas are directly proportional at a constant pressure: V{1}/T{1} = V{2}/T{2}.

What is Dalton's Law of Partial Pressures?

The principle that the total pressure of a gas mixture is the sum of the partial pressures of each individual gas component: P{total} = P{1} + P{2} + … + P{n}.

What is the dilution equation?

The formula used to determine how to prepare a less concentrated solution from a stock solution: M{1}V{1} = M{2}V{2}.

Define a conjugate acid-base pair.

Two chemical species that differ only by the presence or absence of a single proton (H^{+}), such as ammonia (NH{3}) and the ammonium ion (NH{4}^{+}).

What is an amphoteric substance?

A substance that can behave as either a Brønsted-Lowry acid or a Brønsted-Lowry base, such as water (H_{2}O).

State Gay-Lussac's Law.

A gas law stating that the pressure of a given mass of gas is directly proportional to its absolute temperature when the volume is kept constant: \frac{P{1}}{T{1}} = \frac{P{2}}{T{2}}.

What is electron configuration?

The distribution of electrons of an atom or molecule in atomic or molecular orbitals (e.g., 1s^{2}2s^{2}2p^{6}).

Define the Pauli Exclusion Principle.

A principle stating that no two electrons in an atom can have the same set of four quantum numbers, meaning an orbital can hold a maximum of two electrons with opposite spins.

What is Hund's Rule?

The rule that every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

Define enthalpy (H).

A thermodynamic property of a system equal to the system's internal energy plus the product of its pressure and volume; changes in enthalpy (\Delta H) represent heat flow at constant pressure.

What is entropy (S)?

A measure of the degree of randomness or disorder in a system; the Second Law of Thermodynamics states that the total entropy of an isolated system can never decrease over time.

Explain Le Châtelier's Principle.

The principle that if a change in temperature, pressure, or concentration is applied to a system at equilibrium, the system will shift its equilibrium position to counteract the effect of the disturbance.

What are oxidation and reduction (Redox)?

Oxidation is the loss of electrons by a substance, while reduction is the gain of electrons by a substance.

Define an Arrhenius acid.

A substance that increases the concentration of hydrogen ions (H^{+}) when dissolved in water.

Define an Arrhenius base.

A substance that increases the concentration of hydroxide ions (OH^{-}) when dissolved in water.

What are significant figures?

The digits in a measurement that carry meaning contributing to its precision, consisting of all certain digits plus one final estimated digit.

Define the Law of Multiple Proportions.

The principle stating that if two elements form more than one compound, the various masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.

What is scientific notation?

A method of expressing numbers as the product of a coefficient between 1 and 10 and a power of 10, formatted as M \times 10^{n}.

Explain resonance in chemical bonding.

A condition occurring when more than one valid Lewis structure can be written for a molecule or polyatomic ion, where the actual electron distribution is an average of these resonance forms.

What is molality (m)?

A unit of concentration defined as the number of moles of solute per kilogram of solvent (m = mol/kg), which remains constant with temperature changes.

Define colligative properties.

Physical properties of a solution, such as boiling point elevation or freezing point depression, that depend solely on the total number of dissolved solute particles rather than their chemical identity.

What does the Gibbs Free Energy change (\Delta G) indicate?

A thermodynamic value used to predict reaction spontaneity; a negative value (\Delta G < 0) indicates a spontaneous process at constant temperature and pressure.

Differentiate between sigma (\sigma) and pi (\pi) bonds.

A sigma bond is formed by the end-to-end overlap of atomic orbitals along the internuclear axis, while a pi bond results from the side-to-side overlap of parallel p-orbitals.

Describe the Bohr Model of the atom.

A structural model where electrons travel in specific circular orbits, or energy levels, at fixed distances from the nucleus, corresponding to quantized energy states.

What is the Equilibrium Constant (K_{eq})?

A numerical value that expresses the ratio of the concentrations of products to reactants at chemical equilibrium, each raised to the power of their stoichiometric coefficients.

What is Graham’s Law of Effusion?

A law stating that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass (Rate \propto 1/\sqrt{M}).