General Chemistry Review: Measurement, Atomic Structure, and Mass Relationships

Flashcards covering key terms and definitions across General Chemistry Chapters 1, 2, and 3.

Chemistry

The study of matter and the changes it undergoes.

Matter

Anything that occupies space and has mass.

Substance

A form of matter that has a definite composition and distinct properties.

Mixture

A combination of two or more substances in which the substances retain their distinct identities.

Homogeneous Mixture

A mixture in which the composition is uniform throughout.

Heterogeneous Mixture

A mixture in which the composition is not uniform throughout.

Element

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

Compound

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

Physical Change

A process that does not alter the composition or identity of a substance.

Chemical Change

A process that alters the composition or identity of the substance(s) involved.

Extensive Property

A property of a material that depends upon how much matter is being considered.

Intensive Property

A property of a material that does not depend upon how much matter is being considered.

Mass

A measure of the quantity of matter in an object.

Weight

The force that gravity exerts on an object.

Density

An SI derived unit defined as mass divided by volume: $d = \frac{m}{v}$.

Accuracy

How close a measurement is to the true value of the quantity that was measured.

Precision

How close a set of measurements are to each other.

Hypothesis

A tentative explanation for a set of observations.

Law

A concise statement of a relationship between phenomena that is always the same under the same conditions.

Theory

A unifying principle that explains a body of facts and/or those laws that are based on them.

Atom

The extremely small particles of which elements are composed.

Molecule

An aggregate of two or more atoms in a definite arrangement held together by chemical forces.

Diatomic Molecule

A molecule containing only two atoms.

Polyatomic Molecule

A molecule containing more than two atoms.

Ion

An atom, or group of atoms, that has a net positive or negative charge.

Cation

An ion with a positive net charge formed when a neutral atom loses one or more electrons.

Anion

An ion with a negative net charge formed when a neutral atom gains one or more electrons.

Monatomic Ion

An ion that contains only one atom.

Polyatomic Ion

An ion that contains more than one atom.

Atomic Number ($Z$)

The number of protons in the nucleus of each atom of an element.

Mass Number ($A$)

The total number of neutrons and protons present in the nucleus of an atom of an element.

Isotopes

Atoms of the same element ($X$) with different numbers of neutrons in their nuclei.

Molecular Formula

A chemical formula that shows the exact number of atoms of each element in the smallest unit of a substance.

Empirical Formula

A chemical formula that shows the simplest whole-number ratio of the atoms in a substance.

Thomson's Model

A atomic model proposing a sphere of positive charge spread over the entire sphere with embedded electrons.

Oxoacid

An acid that contains hydrogen, oxygen, and another central element.

Base

A substance that yields hydroxide ions ($\text{OH}^-$) when dissolved in water.

Hydrate

A compound that has a specific number of water molecules attached to its formula unit.

Atomic Mass Unit ($\text{amu}$)

A mass unit defined as exactly one-twelfth the mass of one carbon-12 atom.

Average Atomic Mass

The weighted average of all of the naturally occurring isotopes of an element.

Mole ($\text{mol}$)

The amount of a substance that contains exactly $6.0221415 \times 10^{23}$ elementary entities.

Avogadro's Number ($N_A$)

The number of elementary entities in one mole of a substance, equal to $6.022 \times 10^{23}$.

Molar Mass

The mass in grams (or kilograms) of 1 mole of units of a substance.

Molecular Mass

The sum of the atomic masses (in $\text{amu}$) of all the atoms in a molecule.

Formula Mass

The sum of the atomic masses (in $\text{amu}$) in a formula unit of an ionic compound.

Percent Composition

The percent by mass of each element in a compound.

Chemical Reaction

A process in which one or more substances are changed into one or more new substances.

Chemical Equation

A representation using chemical symbols to show what happens during a chemical reaction.

Reactants

The starting materials in a chemical reaction.

Products

The substances formed as a result of a chemical reaction.

Limiting Reagent

The reactant used up first in a chemical reaction, which limits the amount of product formed.

Excess Reagent

The reactant present in a quantity greater than necessary to react with the limiting reagent.

Theoretical Yield

The amount of product that would result if all the limiting reagent reacted.

Actual Yield

The amount of product actually obtained from a reaction.

Percent Yield

The ratio of actual yield to theoretical yield multiplied by 100%: $\%\text{ Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$.

Atom Economy

A measure of reaction efficiency, calculated as: $\text{atom economy} = \frac{\text{total mass of atoms in product}}{\text{total mass of atoms in all reactants}} \times 100\%$.