substance
matter that has a uniform and unchanging composition
chemical change
a process involving one or more substances changing into new substances; also called a chemical reaction
chemical property
the ability or inability of a substance to combine with or change into one or more new substances
chromatography
a technique that is used to separate the components of a mixture based on the tendency of each component to travel or be drawn across the surface of another material
compound
a chemical combination of two or more different elements; can be broken down into simpler substances by chemical means and has properties different from those of its component elements
crystallization
a separation technique that produces pure solid particles of a substance from a solution that contains the dissolved substance
distillation
a technique that can be used to to physically separate most homogeneous mixtures based on the differences in the boiling points of the substances involved
element
a pure substance that cannot be broken down into simpler substances by physical or chemical means
extensive property
a physical property, such as mass, length, and volume, that is dependent upon the amount of substance present
filtration
a technique that uses a porous barrier to separate a solid from a liquid
gas
a form of matter that flows to conform to the shape of its container, fills the container's entire volume, and is easily compressed
heterogeneous mixture
one that does not have a uniform composition and in which the individual substances remain distinct
homogeneous mixture
one that has a uniform composition throughout and always has a single phase; also called a solution
intensive property
a physical property that remains the same no matter how much of a substance is present
law of conservation of mass
states that mass is neither created nor destroyed during a chemical reaction but is conserved; mass (reactants)= mass (products)
law of definite proportions
states that, regardless of the amount, a compound is always composed of the same elements in the same proportion by mass
law of multiple proportions
states that when different compounds are formed by the combination of the same elements, different masses of one element combine with the same mass of the other element in a ratio of small whole numbers
liquid
a form of matter that flows, has constant volume, and takes the shape of its container
mixture
a physical blend of two or more pure substances in any proportion in which each substance retains its individual properties; can be separated by physical means
percent by mass
a percentage determined by the ratio of the mass of each element to the total mass of the component; mass (element) / mass (compound) x 100
periodic table
a chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns (groups or families) arranged by increasing atomic numbers
physical change
a type of change that alters the physical properties of a substance but does not change its composition
physical property
a characteristic of matter that can be observed or measured without changing the sample's composition- for example, density, color, taste, hardness, and melting point
solid
a form of matter that has its own definite shape and volume, is compressible, and expands only slightly when heated
solution
a uniform mixture that may contain solids, liquids, or gases; also called a homogeneous mixture
states of matter
the physical forms in which all matter naturally exists on Earth- most commonly as a solid, a liquid, or a gas
vapor
gaseous state of a substance that is a liquid or a solid at room temperature
periods
horizontal rows in a periodic table
groups/families
vertical columns in a periodic table; these elements have similar but not identical characteristics