Matter and Measurement

Comprehensive review of matter types, changes of state, measurement rules (significant figures, density), and percent error based on the lecture notes.

Elements

Pure substances composed of only one kind of atom.

Binary compounds

Substances made up of only two kinds of atoms, such as $H_2O$, $NH_3$, or $CO_2$.

Diatomic molecules

Elements that form two atom molecules in their natural form at STP, often remembered by the phrase ‘HOFBrINCl’.

Heterogeneous mixtures

Mixtures that have discernable components and are not uniform throughout, such as soil or chocolate-chip cookies.

Homogeneous mixtures

Mixtures that are uniform throughout with particles evenly distributed; also known as a solution.

Physical changes

Changes that do not form new substances but merely change the appearance of the original material, such as the melting of ice.

Chemical changes

Changes that result in the formation of new substances, such as the burning of hydrogen gas to produce water vapor.

Solid

A state of matter that is rigid, with a fixed shape and a fixed volume.

Liquid

A state of matter that is not rigid, has no fixed shape, but has a fixed volume.

Gas

A state of matter that is not rigid and has no fixed shape and no fixed volume.

Kelvin (K)

The temperature scale used for gas laws, where $K = C + 273$.

Celsius (C)

The temperature scale used for phase changes, heat questions, and measurements in the lab.

Density

An intensive property that relates mass and volume, defined as mass per unit of volume: $d = \frac{m}{V}$.

Percent error

The absolute value of the difference between the experimental (measured) value and theoretical (accepted) value, divided by the accepted value and multiplied by $100\%$. Formula: $\frac{|\text{experimental value} - \text{accepted value}|}{|\text{accepted value}|} \times 100\%$.

Pacific Rule (Significant Figures)

The rule used when a decimal is present; start on the Pacific/left side and move toward the first non-zero number; that number and those following are significant.

Atlantic Rule (Significant Figures)

The rule used when a decimal is absent; start on the Atlantic/right side.

Water Displacement Method

A method used to find volume by subtracting the ‘Initial’ volume from the ‘Final’ volume of water in a graduated cylinder.