Lecture Notes: States of Matter, Classification, and Notation 1.1-1.3

Vocabulary flashcards covering states of matter, classification into pure substances and mixtures, properties of mixtures, basic chemistry concepts (elements, compounds, molecules, atoms), and notation concepts (standard and scientific notation, implicit 1, subscripts).

Solid

State of matter with a definite shape and volume; particles are tightly packed and vibrate; does not take the container's shape.

Liquid

State of matter with a definite volume that takes the container's shape; particles are less tightly packed than in a solid and flow.

Gas

State of matter with neither definite shape nor definite volume; particles move freely and are spaced far apart; highly compressible.

Physical state

Classification of matter as solid, liquid, or gas based on shape, volume, and particle motion.

Freedom of motion

Extent to which particles can move; solids have the least freedom, gases the most.

Shape (of matter)

Solids keep their shape; liquids and gases take the shape of their container.

Packing

How closely particles are arranged; solids and liquids are densely packed, gases have large spaces between particles.

Compressibility

Ability to be squeezed into a smaller volume; gases are compressible; solids and liquids are not.

Pure substance

Matter with a fixed composition consisting of one component; cannot be separated into simpler substances by physical means.

Mixture

Matter made of two or more substances physically combined; can be homogeneous or heterogeneous.

Element

Pure substance that cannot be broken down into simpler substances; consists of one kind of atom.

Compound

Pure substance formed from two or more different elements chemically combined; always a molecule (e.g., H2O, Fe2O3).

Molecule

Two or more atoms bonded together; can be a molecule of an element (O2) or a molecule of a compound (H2O).

Atom

The basic unit of an element; cannot be broken down by chemical means; combines with others to form molecules.

Homogeneous mixture

Uniform composition throughout the sample; components are not distinguishable (e.g., Gatorade).

Heterogeneous mixture

Nonuniform composition; components are visibly different (e.g., oil and water).

Gatorade (as a mixture)

An example of a homogeneous mixture containing water, sugar, salt, and flavoring; appears uniform throughout.

H2O

Water; a compound consisting of hydrogen and oxygen (H2O); pure substance with molecules.

H2

Hydrogen gas; element; diatomic molecule; pure substance.

O2

Oxygen gas; element; diatomic molecule; pure substance.

Fe2O3

Iron(III) oxide; compound; pure substance.

Physical change

A change where the substance's identity remains the same; the formula may stay the same (e.g., H2O(l) to H2O(s)).

Chemical change

A change that alters the chemical composition and identity of a substance (e.g., H2 + O2 → H2O).

Standard number

The normal decimal notation of a number (e.g., 2500).

Scientific notation

Expressing numbers as a × 10^n, where a is between 1 and 10; used for very large or small numbers.

Implicit 1 in formulas

If no subscript is written after an element, it means there is one atom of that element.

Subscript

A small number following an element in a chemical formula indicating how many atoms of that element are present.

Chemistry

The study of matter

Matter

Anything that occupies space and has mass