Comprehensive Chemistry Key Terms: Matter, Mixtures, Changes, Measurements, and SI Units

Matter

Anything with mass + volume

Element

Pure substance; one type of atom

Compound

Pure substance; 2+ elements chemically bonded

Homogeneous mixture

Uniform throughout

Heterogeneous mixture

Non-uniform

Evaporation

Separates dissolved solid from liquid

Distillation

Separates liquids by boiling points

Filtration

Separates solid from liquid

Chromatography

Separates substances by movement/attraction

Physical change

Identity stays the same

Chemical change

New substance forms

Qualitative

Describes; no numbers

Quantitative

Uses numbers/measurements

Measurement

Number + unit

Accuracy

Closeness to true value

Precision

Repeatability/consistency

Systematic error

Consistent error; minimize by calibration

Random error

Unpredictable variation; repeat/average

Significant figures

Meaningful digits in a measurement

×/÷ sig figs

Fewest sig figs

+/− sig figs

Fewest decimal places

Nonzero digits

Always significant

Middle zeros

Always significant

Leading zeros

Never significant

Ending zeros + decimal

Significant

Ending zeros, no decimal

Not significant

Exact number

No measurement uncertainty

Inexact number

Measured; has uncertainty

Uncertainty

Estimated/uncertain last digit

Scientific notation

a × 10ⁿ; 1 ≤ a < 10

Mega

M = 10⁶

Kilo

k = 10³

Hecto

h = 10²

Deka

da = 10¹

Base

10⁰

Deci

d = 10⁻¹

Centi

c = 10⁻²

Milli

m = 10⁻³

Micro

μ = 10⁻⁶

Nano

n = 10⁻⁹

Pico

p = 10⁻¹²

SI length

meter (m)

SI mass

kilogram (kg)

SI time

second (s)

SI temperature

kelvin (K)

Amount

mole (mol)

Energy

joule (J)

Volume

liter (L)

1 in

2.54 cm

1 cm³

1 mL

1 kg

2.20 lb

Dimensional analysis

Convert by canceling units

Conversion factor

Equivalent ratio = 1

Δ

Final − initial

Density

mass ÷ volume

Density formula

D = m/V

Mass formula

m = D×V

Volume formula

V = m/D

Solid density

g/cm³

Liquid density

g/mL

Gas density

g/L

Water displacement

Final volume − initial volume

Thermometer

Measures temperature

Temperature

Related to average kinetic energy

Freezing water

0°C = 273.15 K = 32°F

Boiling water

100°C = 373.15 K = 212°F

Absolute zero

0 K = −273.15°C

K from °C

K = °C + 273.15

°C from K

°C = K − 273.15

°F from °C

°F = 9/5(°C) + 32

°C from °F

°C = 5/9(°F − 32)

Independent variable

Changed/manipulated

Dependent variable

Measured/responding

Graph x-axis

Independent variable

Graph y-axis

Dependent variable