Chapter 2: Evidence Collection and Preservation

Vocabulary flashcards created from lecture notes covering physical and chemical changes and properties, mass and weight, accuracy and precision, density, SI base units, and metric prefixes.

Physical Change

A transformation of matter that does not alter its chemical identity, such as the boiling of water or breaking glass.

Chemical Change

A process where matter undergoes a chemical reaction and forms a new substance, such as the rusting of iron or burning of wood.

Physical Property

A property of a substance that can be measured without altering its chemical identity, such as boiling point, melting point, solubility, and density.

Chemical Property

The types of chemical reactions or changes that a substance can undergo, such as flammability, corrosiveness, and explosiveness.

Mass

A measure of how much matter is contained in a sample, which does not depend on gravity and does not change from one location to another.

Weight

A measure of how strongly gravity is pulling on matter.

Accuracy

How close experimental results are to the actual (true) value.

Precision

How reproducible experimental results are if the same experiment is repeated multiple times.

Shot Target Comparison (Accuracy vs. Precision)

Target 1 represents good accuracy and good precision; Target 2 represents poor accuracy and good precision; Target 3 represents poor accuracy and poor precision.

Density

The ratio of an object's mass to its volume, expressed as $\text{density} = \frac{\text{mass}}{\text{volume}}$.

Pumice

A substance with a density of $0.60\,g/mL$ that floats in water because its density is less than water's density ($1.00\,g/mL$).

Obsidian

A substance with a density of $2.60\,g/mL$ that sinks in water because its density is greater than water's density ($1.00\,g/mL$).

Mole

The SI base unit for amount of substance ($mol$), where $1\,mol = 6.023 \times 10^{23}$ atoms or particles.

SI Base Unit of Length

The meter ($m$).

SI Base Unit of Mass

The kilogram ($kg$).

SI Base Unit of Temperature

The kelvin ($K$).

Kilo- ($k$)

A unit prefix representing a factor of $10^3$ ($1000$).

Milli- ($m$)

A unit prefix representing a factor of $10^{-3}$ ($0.001$).

Micro- ($\mu$)

A unit prefix representing a factor of $10^{-6}$ ($0.000001$).

Nano- ($n$)

A unit prefix representing a factor of $10^{-9}$.