GENCHEM TERM 1 EXAM

Comprehensive vocabulary flashcards covering basic chemical definitions, properties of matter, atomic structure, stoichiometry, gas laws, and kinetic molecular theory.

Matter

The "stuff" of which the universe is composed; has mass and occupies space.

Solid

Rigid; has a fixed shape and volume (e.g., ice cube, diamond).

Liquid

Has a definite volume but takes the shape of its container (e.g., water, blood).

Gas

Has no fixed shape or volume; takes the shape and volume of its container (e.g., air, helium).

Physical properties

Characteristics observed without changing the composition of a substance (e.g., color, melting point, density).

Chemical properties

Characteristics observed when matter is involved in a chemical change, resulting in new chemical substances.

Precipitate

An insoluble product formed during a chemical reaction.

Extensive property

A property that changes when the amount of material changes, such as mass, length, and volume.

Intensive property

A property that does not depend on the size of the material, such as temperature, color, or density.

Intrinsic properties

Characteristics of a substance regardless of its shape and size, such as viscosity, taste, and transparency.

Extrinsic properties

Characteristics of a substance which pertain only to its appearance, including shape, length, mass, and temperature.

Elements

Substances that cannot be broken down into other substances by chemical means.

Compounds

Substances formed when two or more elements combine through a chemical change.

Homogeneous mixture

A mixture that is the same throughout; also referred to as a solution.

Heterogeneous mixture

A mixture containing regions that have different properties from those of other regions.

Pure substance

Matter that always has the same composition, appearing as either elements or compounds.

Decanting

Separating a dense, insoluble substance from a mixture by pouring off the liquid (supernatant) layer.

Sieving

The process of separating a mixture based on different sizes of components as they pass through holes.

Filtration

A special form of sieving that separates very fine solid particles from liquid or gas mixtures using filter paper.

Centrifugation

The process of spinning tubes of heterogeneous mixtures at very high speeds to force particles to settle.

Distillation

Separating a mixture by evaporation and collecting the cooled liquid, known as the distillate.

Chromatography

A method primarily used for identifying and analyzing liquid or gas mixtures using very small quantities.

Chemical Formula

A symbolic expression or shorthand describing the types and number of atoms in a substance.

Atomic number ($Z$)

The value giving the number of protons in the nucleus of an atom.

Mass number ($A$)

The sum of the number of protons and neutrons in an atom.

Nucleons

The collective name for protons and neutrons in an atom.

Isotopes

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

Frederick Soddy

The British Chemist who introduced the term "isotope" from the Greek words isos and topos.

Ionic compound

A substance formed between a metal atom and a nonmetal atom through ionic bonds.

Cation

A positive ion formed when metal atoms give away valence electrons.

Anion

A negative ion formed when nonmetal atoms accept valence electrons.

Covalent compound

A substance formed between two or more nonmetal atoms joined by covalent bonds.

Mole

The amount of substance that contains as many entities as there are atoms in exactly $0.012\,kg$ of pure carbon-12.

Avogadro’s number

The value representing one mole, equal to $6.022 \times 10^{23}$ entities.

Formula mass

The sum of all mass numbers of the atoms that make up a compound, expressed in unified atomic mass units ($u$).

Empirical Formula

The lowest whole-numbered ratio of the elements in a compound.

Molecular Formula

The actual composition of a compound indicating the specific number of atoms per element.

Antoine Lavoisier

The French chemist who discovered the Law of Conservation of Mass.

Diatomic substance

Elements like nitrogen and hydrogen that exist as two atoms in their natural gaseous state (e.g., $N_2$, $H_2$).

Stoichiometry

The study of the quantities of materials consumed and produced in chemical reactions.

Theoretical yield

The yield calculated by assuming that a reaction goes to completion.

Actual yield

The amount of a specified pure product actually obtained from a given reaction in practice.

Percent yield

A measurement calculated by dividing actual yield by theoretical yield multiplied by $100\%$.

Limiting reagent

The reactant that is used up first in a chemical reaction and determines the theoretical yield.

Excess reagent

Reactants present in quantities greater than what is needed by the chemical reaction.

Pressure ($P$)

The force exerted per unit area, often expressed as $P = \frac{F}{A}$.

Boyle’s Law

The law stating volume is inversely proportional to pressure at constant temperature ($P_1V_1 = P_2V_2$).

Charles’ Law

The law stating volume is directly proportional to absolute temperature at constant pressure (\frac{V_1}{T_1} = \frac{V_2}{T_2}).

Ideal Gas Law

The single equation summing gas behavior: $PV = nRT$.

Graham’s Law of Diffusion

The principle that gas diffusion rate is inversely proportional to the square root of its molar mass ($\frac{v_1}{v_2} = \sqrt{\frac{M_2}{M_1}}$).