Chemistry Unit 1 Vocab

Matter

any substance that has mass and volume — space that the stuff makes up

Element

only one type of atom is present; ex: C, Fe, F₂, Cl₂, Br₂, I₂, S₈, P₄

Compound

when two or more different atoms are bonded chemically; ex: H₂0, NaCl, C₆H₁₂O₆

Pure Substance

when only one chemical formula is present in the sample; has a set composition (formula) and properties; ex: Elements, molecules, and compounds

Heterogenous Mixture

when two or more substances are physically combined; each substance is not chemically changed and retains its properties; when substances are not uniformly distributed (clumping); have 2+ phases; the pure substances have different properties from each other

Homogenous Mixture

when two or more substances are physically combined; each substance is not chemically changed and retains its properties; when substances are uniformly distributed (spread out evenly); only 1 phase; pure substance properties are similar

Physical Change

A change that affects one or more physical properties of a substance without altering its chemical composition. Examples include changes in state, shape, or size.

Physical Property

A characteristic of a substance that can be observed or measured without changing its identity, such as color, odor, boiling point, and melting point.

Chemical Change

A change that results in the formation of new chemical substances, often involving a change in energy and the breaking and forming of bonds. Examples include combustion, fermentation, and rusting.

Chemical Property

A characteristic of a substance that can only be observed during a chemical reaction, revealing its ability to undergo specific chemical changes. Examples include reactivity, flammability, and acidity.

Density

mass over volume; a physical property that measures how much mass is packed into a specific amount of space

Solid

state of matter; particles shake/vibrate in fixed positions; particles are very close to each other (but not bonded); low freedom of movement; high in density (usually); a set volume and shape

Liquid

state of matter; particles are flowing; particles are still quite close (but not bonded); higher freedom of movement; slightly lower in density; a set volume but variable shape

Gas

state of matter; particles are flying; particles are not close; gases have the highest freedom of movement; lowest density; no set volume or shape

Filtering

used for heterogenous mixtures and based on difference in state of matter and density; solution is poured through a funnel with filter paper, the solid gets stuck while the liquid drips through and pools

Chromatography

separates multiple solids fully dissolved in liquid; does not collect solids, only “spread them out“; used for comparison (inks)

Evaporation

Used for homogenous liquid+solid mixtures; based on large difference in boiling point and state of matter

Decanting

used for heterogenous liquid+liquid mixtures; based on difference in density; a mixture is slowly and carefully poured to separate the substances; a separation funnel could also be used

Centrifuging

separates solids suspended in a liquid; won’t settle (ex. blood)

Distilling

used for homogenous liquid+liquid mixtures; based on difference in boiling point; liquid is collected after; collected liquid considered purified

Inert

chemically unreactive

Molecule

when two or more atoms are bonded chemically

gas pressure

the total force exerted by gas particles as they constantly collide with the inner walls of their container, divided by the surface area of those walls

Temperature

a measure of the average kinetic energy of the atoms or molecules in a system