Elements, Compounds & Mixtures Composition of Matter Composition of Matter

Pure Substances: a form of matter that has a definite composition and distinct properties. Elements Fe(s), N2(g), S8(s) All the atoms are alike. Indivisible substances. 90 Atoms found in nature. All listed on the Periodic Table of the Elements. Represented by a chemical symbol. Gold Element #79 Symbol: Au Cannot be created or destroyed. Composition of Matter

Pure Substances: a form of matter that has a definite composition and distinct properties. Compounds FeS(s), CH4(g), NaNO3(s), H2O(l) Two or more kinds of atoms chemically combined. Can be broken down into two or more elements. Represented by a chemical formula describing the ratio of elements. “Salt” Chemical Compound of Sodium (metal) and Chlorine (gas) Formula: NaCl Composition of Matter

Mixtures Various physical combinations of substances. Indistinguishable ingredient mixtures are homogeneous. Distinguishable ingredients mixtures are heterogeneous. Composition of Matter

Homogeneous Mixtures Two or more solid, liquid, or gaseous substances blended evenly throughout. Solutions Particles too small to be seen, that never settle. Constantly uniformly mixed. Appears to be a pure substance. Mixed substances can be separated. Composition of Matter

Heterogeneous Mixtures 80% Cotton 20% Polyester Composition of Matter

More Heterogeneous Mixtures Colloids Large particles that don’t settle. Scatters Light – the Tyndall Effect. Examples: Fog / Clouds Milk Orange Juice Jell-O Composition of Matter

More Heterogeneous Mixtures Suspensions Large particles Settles when not disturbed. Examples Muddy water “Italian” salad dressing Dusty air Composition of Matter