Unit 2 Matter and Change

chemical change

(chemistry) any process determined by the atomic and molecular composition and structure of the substances involved

heterogeneous mixture

A mixture in which different materials can be distinguished easily

physical change

a change from one state (solid or liquid or gas) to another without a change in chemical composition

physical property

a characteristic of a substance that does not involve a chemical change, such as density, color, or hardness

chemical formula

a combination of chemical symbols and numbers to represent a substance

mixture

a combination of two or more substances that are not chemically combined

law of conservation of mass

a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system

solution

a homogeneous mixture of two or more subtances uniformly dispersed throughout a single phase

pure substance

a sample of matter; either a single element or a single compound, that has definite chemical and physical properties

liquid

a substance in the fluid state of matter having no fixed shape but a fixed volume

compound

a substance made up of atoms of two or more different elements

element

a substance that cannot be separated or broken down into simpler substancesby chemical means; all atoms of an element have the same atomic number

matter

anything that has mass and takes up space

gas

matter that does not have a definite shape or volume

solid

of definite shape and volume

reactivity

ready susceptibility to chemical change

crystalline solid

solids in which the particles are arranged in a repeating, 3-D pattern, has a specific melting point

temperature

the degree of hotness or coldness of a body or environment (corresponding to its molecular activity)

law of conservation of energy

the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes

dissolving

the process of a material becoming incorporated uniformly into another, or of two materials mixing together evenly

molecule

the smallest unit of a substance that keeps all of the physical and chemical properties of that substance

thermal energy

total amount of energy associated with the random movement of atoms and molecules in a sample of matter

flammability

a material's ability to burn in the presence of oxygen

homogeneous mixture

a mixture in which substances are evenly distributed throughout the mixture

diatomic molecule

a molecule consisting of two atoms

surface tension

a phenomenon at the surface of a liquid caused by intermolecular forces

chemical property

a property used to characterize materials in reactions that change their identity

density

a ration of the mass of a substance to the volume of the substance

sublimination

the change of a substance from a solid to a gas

freezing

the change of state from a liquid to a solid

evaporation

the process of becoming a vapor

condensation

the process of changing from a gaseous to a liquid or solid state

melting

the process whereby heat changes something from a solid to a liquid

atom

the smallest unit of an element that maintains the properties of that element

melting point

the temperature and pressure at which a solid becomes a liquid

boiling point

the temperature at which a liquid becomes a gas

plasma

(physical chemistry) a fourth state of matter distinct from solid or liquid or gas and present in stars and fusion reactors

kinetic theory

(physics) a theory that gases consist of small particles in random motion

energy

(physics) the capacity of a physical system to do work

amorphous solid

A solid made up of particles that are not arranged in a regular pattern