Chemistry Review Vocabulary Flashcards: Sig Figs to Avogadro's Number

Key vocabulary terms with concise definitions covering significant figures, scientific notation, measurements, matter types, periodic table concepts, ionic/covalent compounds, and Avogadro's number.

Significant figures

Digits in a measurement that indicate precision, including all certain digits and the first uncertain digit.

Leading zeros

Zeros that precede all nonzero digits and are not considered significant.

Addition/subtraction sig fig rule

When adding or subtracting, round the result to the least precise decimal place among the quantities.

Multiplication/division sig fig rule

When multiplying or dividing, round the result to the smallest number of significant figures among the factors.

Scientific notation

A way of writing numbers as a × 10^n with 1 ≤ a < 10 to handle very large or small values.

Displacement method

A method to measure the volume of an irregular object by the amount of liquid it displaces.

Density

Mass per unit volume (ρ = m/V); commonly in g/mL or g/cm^3.

Mass

The amount of matter in an object, measured in grams or kilograms.

Volume

The amount of space a substance occupies, measured in mL, L, or cm^3.

Conversion factor

A ratio that expresses how many of one unit are equal to another, used in dimensional analysis.

Dimensional analysis

Problem-solving method using units to convert between measurement systems.

Element

A substance composed of only one kind of atom; cannot be broken down into simpler substances chemically.

Compound

A substance formed from two or more elements in a fixed ratio; can be decomposed chemically.

Homogeneous mixture

A mixture with uniform composition throughout; components are not visibly different.

Heterogeneous mixture

A mixture with visibly different substances or phases.

Solution

A homogeneous mixture of a solute dissolved in a solvent.

Atomic number

The number of protons in an atom's nucleus; identifies the element.

Mass number

Total number of protons and neutrons in the nucleus; describes isotopes.

Isotope

Atoms of the same element with different numbers of neutrons, giving different mass numbers.

Ion

An atom or molecule with a net electric charge due to loss or gain of electrons.

Atomic symbol

The short symbol representing an element (e.g., H, Fe).

Nucleus

The center of an atom containing protons and neutrons; electrons surround it.

Period

A horizontal row on the periodic table.

Group

A vertical column on the periodic table; elements in a group have similar properties.

Metal

A material that is typically solid, conducts electricity, and is malleable and ductile.

Nonmetal

An element poor in electrical conductivity; many are gases or brittle solids.

Metalloid

An element with properties between metals and nonmetals; often semiconductors.

Transition metals

Elements in groups 3–12 with variable oxidation states and good conductivity.

Alkali metals

Group 1 metals that are highly reactive and form +1 ions.

Alkaline earth metals

Group 2 metals that are reactive and form +2 ions.

Noble gases

Group 18 elements that are generally inert and gases at room temperature.

Ionic compound

Compound formed from metal and nonmetal; consists of ions held by electrostatic forces.

Covalent (molecular) compound

Compound formed between nonmetals; atoms share electrons.

Formula unit

The lowest whole-number ratio of ions in an ionic compound.

Avogadro's number

6.022 × 10^23 particles per mole; the amount of substance containing that many particles.

Mole

A unit of amount of substance that contains Avogadro's number of particles.

Molar mass

Mass of one mole of a substance (g/mol).

Molar mass calculation

Sum of the atomic masses in a chemical formula.

Moles to grams

Convert moles to grams by multiplying by the substance's molar mass.

Mass to moles

Convert grams to moles by dividing by the substance's molar mass.