AP Chemistry - Matter, Measurement, and Problem Solving (Vocabulary)

Vocabulary flashcards covering key terms from Unit 1: Matter, Measurement, and Problem Solving (AP Chemistry).

Solid

A state of matter with a definite shape and volume; particles are tightly packed and vibrate in place.

Liquid

A state with definite volume but takes the shape of its container; particles flow past one another.

Gas

A state with neither definite shape nor volume; expands to fill the space available.

Crystalline

A solid with an ordered, repeating internal arrangement (crystal lattice).

Amorphous

A solid lacking long-range order; examples include glass and plastics.

Pure substance

Matter with uniform composition and fixed properties; either an element or a compound.

Mixture

Matter composed of two or more substances physically combined; can be homogeneous or heterogeneous.

Element

A pure substance composed of only one type of atom; cannot be broken down by chemical means into simpler substances.

Compound

A pure substance formed from two or more elements in fixed proportions; can be decomposed into simpler substances by chemical reactions.

Heterogeneous mixture

A mixture with nonuniform composition; distinct phases are visible.

Homogeneous mixture

A uniform composition throughout; also called a solution.

Physical change

A change that alters a substance's form or state without changing its identity (no new substance formed).

Chemical change

A change that results in one or more new substances with different properties.

Physical property

A property observed or measured without changing the substance's composition (e.g., color, density, melting point).

Chemical property

A property describing how a substance behaves in chemical reactions (e.g., flammability, reactivity).

SI base unit

The basic units in the SI system used to measure seven fundamental quantities (meter for length, kilogram for mass, second for time, ampere for electric current, kelvin for temperature, mole for amount of substance, candela for luminous intensity).

Density

Mass per unit volume; d = m/v; commonly expressed in g/cm3 or kg/m3.

Mass

A measure of the amount of matter in an object; SI base unit is the kilogram (kg).

Volume

The amount of space occupied by an object; common units are liters (L) or cubic meters (m3).

Temperature scales

The three common scales: Celsius (°C), Kelvin (K), and Fahrenheit (°F).

Celsius to Kelvin relation

K = C + 273.15.

Fahrenheit to Celsius relation

C = (F − 32) × 5/9.

Kelvin to Celsius relation

C = K − 273.15.

Absolute zero

0 K, which equals −273.15 °C; the lowest possible temperature.

Accuracy

Closeness of a measured value to the true value.

Precision

Reproducibility of measurements; how close repeated measurements are to each other.

Random error

Unpredictable fluctuations in measurement that affect precision.

Systematic error

A consistent bias that affects accuracy in one direction.

Significant figures

Digits in a measured quantity that carry meaning about its precision (all certain digits plus one uncertain digit).

Significant figures rules

For multiplication/division: number of SF in result = fewest SF among inputs; for addition/subtraction: result limited by the least precise decimal place.

Temperature conversion formulas

Equations to convert between Kelvin, Celsius, and Fahrenheit: K = C + 273.15; C = K − 273.15; F = (9/5)C + 32; C = (F − 32) × 5/9.

Density equation and rearrangements

Density = mass/volume (d = m/v); rearrangements: mass = d × v; volume = m / d.