1. Elements, Compounds & Mixtures
Composition of Matter
Composition of Matter

2. 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

3. 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

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

5. 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

6. Heterogeneous Mixtures
80% Cotton
20% Polyester
Composition of Matter

7. 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

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