Matter Unit 3

Flashcards covering key vocabulary from the 'Matter Unit 3' lecture notes, including definitions of matter, pure substances, mixtures, atoms, elements, compounds, and physical/chemical properties and changes.

Matter

Anything that has mass and occupies space. It cannot be created or destroyed; it can only change forms.

Pure Substance

Matter with a fixed composition, such as elements or compounds.

Mixture

Matter that has a variable composition.

Atom

The fundamental unit of matter, composed of protons, neutrons, and electrons. It is defined by the number of protons in its nucleus.

Element

A pure substance that cannot be chemically broken down, consisting of only a single type of atom, and defined by its number of protons.

Diatomic Element

Elements that naturally exist as molecules composed of two atoms, such as hydrogen (H

₂), nitrogen (N

₂), oxygen (O

₂), fluorine (F

₂), chlorine (Cl

₂), bromine (Br

₂), and iodine (I

₂).

Compound

Consists of two or more different atoms bound together (e.g., NaCl, H

₂O, H

₃PO

₄).

Homogeneous Mixture

A mixture that is uniform throughout (e.g., air, saltwater).

Heterogeneous Mixture

A mixture that is not uniform throughout (e.g., a salad, sand + water).

Physical Property

Characteristics of matter that can be changed without altering its composition and are directly observable (e.g., odor, color, volume, state, density, melting point, boiling point).

Chemical Property

A substance's ability to form new substances; characteristics that describe how the composition of matter changes (e.g., flammability, rusting of steel, digestion of food).

Physical Change

A change in a physical property that retains the identity of the substance (e.g., a change of state, size, or shape).

Chemical Change

A change in which the original substance is converted to one or more new substances (e.g., paper burns, iron rusts, silver tarnishes).