CHE 110: OBJ 1

Objective 1 Terms

Scientific Law

Describes observations that are true in widely varying circumstances. Often describe mathematical relationships. However don’t explain why something occurs, only observe that it occurs; predicts what will happen, but doesn’t explain why it happens.

Scientific Theory

An idea that has been tested, refined, and is supported by evidence; also a way of thinking about a particular topic.

Scientific Model

Macroscopic, Submicroscopic, Symbols

Hypothesis

Tentative explanation that hasn’t been tested (tested through experiments).

Observation

Gathering information based on senses or a scientific instrument.

Inference

A logical conclusion or educated guess derived from chemical observations and prior knowledge.

Matter

Anything that has mass and takes up volume.

Solid

Definite shape and volume.

Liquid

Definite volume, but no definite shape as it takes the shape of their container.

Gas

No definite shape or volume, fill any container they occupy.

Pure Substance

Composed of only one element or only one compound.

Element

Substance made of only one type of atom; simplest form of matter.

Compound

Composed of more than 1 element, bound together in fixed ratios; pure substances composed of more than 1 element in a fixed ratio.

Mixture

Contain more than 1 substance and the substances aren’t bound in a fixed ratio. Ratio can be altered to affect properties.

Homogenous Mixture

Components are evenly blended throughout.

Heterogenous Mixture

Components aren’t evenly blended throughout; contains regions with significantly different composition.

Physical Change

Changes that occur without altering the identity of a substance (physical properties can change, but composition stays the same)

Chemical Change

Changes that produce new substances; also called ________ reactions.

Physical Property

Properties of a substance that can be measured without changing the identity of the substance, like: color, temp, mass, volume, shape, hardness, and flexibility.

Chemical Property

Properties of a substance that can’t be measured without changing the identity of a substance, like flammability. To test if something is flammable, we must burn it. If it burns, its no longer the original substance.

Composition

Simple components that make up the material

Structure

Both the composition and arrangement of those simpler substances.

Melting

Heating a substance, solid to liquid.

Vaporization

Heating a substance, liquid to gas.

Condensation

Cooling a substance, gas to liquid.

Freezing

Cooling a substance, liquid to solid.

Sublimation

Heating a substance, solid straight to gas.

Potential Energy

Energy that is stored.

Kinetic Energy

Energy of motion; the faster an object is moving, the greater ______ energy it has.

Heat Energy

A type of kinetic energy involving the movement of particles within a substance; specifically referring to the total kinetic energy transferred from a substance to another.

Endothermic

Physical/ chemical change that absorbs energy from its surroundings.

Exothermic

Physical/ chemical change that releases heat energy to its surroundings.