Compounds and Mixtures
Elements
A pure substance containing only one kind of atom. An element is always uniform all the way through (homogeneous). An element cannot be separated into simpler materials (except during nuclear reactions). Over 100 existing elements are listed and classified on the Periodic Table.
Compounds
A pure substance containing two or more kinds of elements. The atoms are chemically combined in some way. Often times (but not always) they come together to form groups of atoms called molecules. A compound is always homogeneous (uniform). Compounds cannot be separated by physical means. Separating a compound requires a chemical reaction. The properties of a compound are usually different than the properties of the elements it contains.
Salt (NaCl)
Compound
Sugar (C6H12O6)
Compound
Sulfuric Acid (H2SO4)
Compound
Water (H2O)
Compound
Iron (Fe)
Element
Krypton (K)
Element
Titanium (Ti)
Element
Uranium (U)
Element
A dog
Mixture
Air
Mixture
Bronze
Mixture
Concrete
Mixture
Gasoline
Mixture
Alcohol (CH3OH)
Compound
Ammonia (NH3)
Compound
Baking Soda (NaHCO3)
Compound
Dry Ice (CO2)
Compound
Bismuth (Bi)
Element
Diamond (C)
Element
Gold (Au)
Element
Ink
Mixture
Milk
Mixture
Pail of Garbage
Mixture
Pizza
Mixture
Popcorn
Mixture
Wood
Mixture
Electricity
None
Energy
None
Mixtures
Two or more compounds or elements NOT chemically combined. No reaction between substances. Mixtures can be non-uniform (called heterogeneous). Mixtures can also be uniform (called homogeneous) and are known as solutions. Mixtures can be separated into their components by chemical or physical means. The properties of a mixture are similar to the properties of its components.
