Chapter 4: Matter and Energy


Terms in this set (...)

physical state
the condition of matter existing in a solid, liquid, or gas
solid state
matter has a fixed state and a fixed volume, compresses negligibly because particles are tightly packed
liquid state
particles of matter are free to move past one another, particles compress negligibly, volume fixed
gaseous state
tiny particles of matter are widely spaced and uniformly distributed throughout the container, variable shape, variable volume, significant compressibility
solid ---> liquid
liquid---> solid
liquid ---> gas
gas ---> liquid
solid ---> gas
gas ---> solid
pure substances
-composed of only one substance and can't be separated
-definite composition and constant properties
-either an element or a compound
-composed of more than one substance and can be physically separated into its component substances
-2 types: homogeneous and heterogeneous
homogeneous mixture
-mixture that has uniform properties throughout
-has a definite composition and constant properties
-ex: alloys and solutions
heterogeneous mixture
-mixture that doesn't have uniform properties throughout
-has indefinite composition and variable properties
a substance that can be broken down into elements by an ordinary chemical reaction
substance that can't be broken down further by a chemical reaction
a homogeneous mixture of two or more metals
the smallest particle that represents an element
physical property
-refers to characteristics of a pure substance that we can observe without changing the composition of the substance
-include: appearance, melting and boiling points, density, heat/electrical conductivity, solubility, and physical state under normal conditions
chemical property
describes a substance's chemical reactions with other substances and composition of substance changes
physical change
-chemical composition of substance isn't changed; change is is physical state/shape of substance
-ex: phase changes (sublimation, deposition, vaporiaztion) dissolving, grinding
chemical change
-chemical reaction
-composition of substance changes
evidence of chemical change
bubbles, odor, light/release of heat energy, formation of precipitate, permanent color change, oxidation, combustion, fermenting
-used for separating a solid or suspension from a liquid
-heterogenous mixture
-based on particle size
-used to obtain the solvent from a solution
-separation based on different boiling points
-homogeneous mixture
-used to separate out one color from a mixture of colors
-separation based on molecular weight (darker colors heavier)
-refers to the formation of solid crystals from a homogenous solution
-essentially a solid-liquid separation technique
-homogenous mixture
law of conservation of mass
-states that matter is neither created or destroyed
-ex: If 1.0 g of hydrogen combines with 8.0 g of oxygen, 9.0 g of water is produced
law of definite composition
-states that "compounds always contain the same elements in a constant proportion by mass"
-ex: sodium chloride is always 39.3% sodium and 60.7% chlorine by mass, no matter what its source
potential engergy (PE)
stored energy that matter possesses as a result of its position or composition
kinetic energy (KE)
energy that matter has as a result of its motion
heat, light, chemical, electrical, mechanical, nuclear
forms of energy