Introduction to Chemistry: Matter, Measurements, and Density

Practice metric conversions too!

Chemistry

The study of matter and the changes it undergoes.

Density

A physical property calculated by dividing mass by volume ($D = \frac{m}{V}$).

Pure Substance

A form of matter that cannot be separated by physical means.

Mixture

A combination of two or more substances that can be separated by physical means.

Homogeneous Mixture

A mixture that has a uniform composition throughout, such as cake batter or vanilla ice cream.

Heterogeneous Mixture

A mixture that is not uniform in composition, such as sand and water or granite.

Element

A pure substance that cannot be broken down into simpler substances by chemical means, such as phosphorus or boron.

Compound

A pure substance that can be broken down into simpler substances by chemical means, such as hydrochloric acid or sodium chloride ($\text{NaCl}$).

Handpicking and Sieving

A separation technique based on physical size, shape, or color, used for separating a mixture of solid particles.

Sedimentation and Decantation

A separation technique based on density and insolubility, used to separate a heavy, insoluble solid mixed in a liquid (e.g., settling mud or sand out of dirty water).

Separating Funnel

An apparatus used to separate immiscible liquids based on differences in immiscibility and density, such as draining water away from a layer of vegetable oil.

Distillation

A separation technique based on boiling points, used to separate soluble mixtures or mixable liquids (e.g., purifying water or distilling liquor).

Chromatography

A technique based on molecular solubility used to separate complex dissolved solutes, such as splitting black ink into red, yellow, and blue dyes.

Law of Conservation of Matter

The scientific principle stating that matter cannot be created nor destroyed, even when changing states between solid, liquid, and gas.

Accuracy

How close a measured value is to the true or accepted value.

Precision

How close multiple repeated measurements are to each other.

Physical Property

A characteristic of a substance that can be observed without changing its chemical identity, such as color, being tasteless, freezing at $0^\circ\text{C}$, or having a density of $1.0\,\text{g/mL}$.

Chemical Property

A characteristic that describes how a substance reacts chemically, such as being stable under heat, non-combustible, or reacting with acids to produce $\text{CO}_2$.

Physical Change

A transformation that alters a substance's appearance or state without altering its chemical composition, such as ripping paper, breaking glass, boiling water, or dissolving salt in water.

Chemical Change

A process involving the rearrangement of atoms to form new substances, such as burning paper or digesting food.

Density Column Suspension

The phenomenon where a solid piece floats or stays suspended between liquid layers because its density is lower than the liquid layer below it, but higher than the liquid layer above it.

Metric Conversions

The calculation method used to convert units using standard factors.

Metric Conversion Formula

$$\frac{\text{Given Quantity}}{1}\times\frac{\text{Desired UNIT}}{\text{Given UNIT}}$$