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