Elements Compounds Mixtures Composition of Matter Pure Substances

Elements, Compounds & Mixtures Composition of Matter

Pure Substances: a form of matter that has a definite composition and distinct properties. Elements n n n Fe(s), N 2(g), S 8(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. n n Composition of Matter Gold Element #79 Symbol: Au Cannot be created or destroyed.

Pure Substances: a form of matter that has a definite composition and distinct properties. Compounds n n Fe. S(s), CH 4(g), Na. NO 3(s), H 2 O(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: Na. Cl Composition of Matter

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

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