APChem - Chapter 1 Vocabulary

matter

matter

physical material of the universe; it is anything that has mass and occupies space

property

is any characteristic that allows us to recognize a particular type of matter and to distinguish it from other types

element

a substance that cannot be broken down into simpler substances; is composed of only one kind of atom

atom

the smallest representative particle of an element

molecule

a chemical combination of two or more atoms

Gas

(also known as vapor) has no fixed volume or shape; uniformly fills its container; can be compressed to occupy a smaller volume, or can expand to occupy a larger one; the molecules are far apart and moving at high speeds, colliding repeatedly with one another and with the walls of the container (Compressing a gas decreases the amount of space between molecules and increases the frequency of collisions between molecules but does not alter the size or shape of the molecules)

liquid

has a distinct volume independent of its container, assumes the shape of the portion of the container it occupies, not compressible to any appreciable extent; the molecules are packed closely together but still move rapidly, allows the molecules to slide over one another

solid

has both a definite volume and shape, not compressible to any appreciable extent; molecules are held tightly together, but wiggle slightly

pure substance

matter that has a fixed composition and distinct properties (EX: water and table salt)

law of definite proportions (law of constant composition)

a law that states that the elemental composition of a compound is always the same

components

substances making up a mixture

heterogeneous mixture

a mixture where throughout the solution the composition is not uniform

homogeneous mixture

a mixture that is uniform in composition throughout (also known as solutions)

Physical properties

properties that can be measured without changing the composition of a substance (ex: color, freezing point)

Chemical properties

properties that describe the way a substance may change or react to form other substances (ex: flammability)

Intensive properties

a property that does not depend on the amount of sample is being examined (ex: density)

Extensive properties

a property that depends on the amount of sample (ex: mass, volume)

Physical change

changes in physical appearance that occur with no change to chemical composition

Changes of state

physical changes of matter from one state to another (ex: gas to liquid)

chemical change (also called a chemical reaction)

process in which a substance is transformed into a chemically different substance

distillation

a separation process that depends on the different abilities of substances to form gases (important method of separating the components of a homogeneous mixture)

filtration

the process in which solid particles in a liquid or a gaseous fluid are removed by the use of a filter (method of separating the components of a heterogeneous mixture)

energy

the capacity to do work or transfer heat

work

the energy transferred when a force exertened on an object causes a displacement of that object

Heat

the energy used to cause the temperature of an object to increase or decrease

Force

any push or pull exerted on an object

kinetic energy

the energy of motion (increases as its velocity or speed increases)

potential energy

energy that is stored in an object due to its position or condition (can be converted into kinetic energy when the object is released)

Temperature

a measure of the hotness or coldness of an object (a physical property that determines the direction of heat flow)

Absolute zero

the temperature at which all thermal motion ceases (0 K)

precision

a measure of how close a series of measurements are to one another

accuracy

how close a measurement results comes to the true value