Download - Elements, Compounds and Mixtures
Elements, Compounds and Mixtures
Anything that has mass and volumeAll of these things fall into 2 categories
Pure Substance
Mixture
“Same Make-up”
“Different make-up”
Matter which has the same make-up and
properties throughout
A combination of two or more
pieces of matterEach piece keeps
its properties
What is Matter?
Pure Substance Type #1Elements
“pure” substances
Made up of one kind of atom
Can’t be broken down into simpler form; properties
remain constant.
Elements ContinuedElements are written in shorthand with symbols
Oxygen – OHydrogen – HCopper - Cu
Each Element has its own symbol
You will need to know the symbol/element name for
#1-30, 79, 80, and 82
Elements on the Periodic Table• All elements are
displayed on the periodic table.
• Each element is assigned a number and a symbol.
Categories of Elements
• There are 3 categories of elements:
1. Metals2. Nonmetals3. Metalloids
Now, using p. 92 and 93 in your text book create a Venn Diagram that compares and contrasts these three categories. Make sure to include examples
of each!
Metals
• Shiny• Conduct heat and electric current
• Ductile• Malleable
• High melting point• Corrosive (will rust)
Nonmetals
• Generally dull (no luster)• Do NOT conduct heat or electricity
• Brittle or break easily• Not ductile or malleable
• Lower density and melting points than metal
Metalloids
• Solids• Shiny or dull
• Conduct heat and electric current better that nonmetals…but not as well as metals• Can be ductile and malleable
**share some characteristics of metals and some of nonmetals**
O
Pure Substance #2Compounds
Compound2+ atoms/elements
Combined by chemical means in a specific ratioThe new properties are
different from the properties of their original
partsCan only be broken down by chemical change. You
can do this by adding heat or electric current.
More on Compounds• Compounds are written in
shorthand with Formulas
• Molecules represent some compounds
• A formula gives you the elements present in the proper ratio
• Water - H2O has two Hydrogen atoms for every one Oxygen atom
Symbols and Formulas• Each compound has its own formula:
– Aspirin• C9H8O4
– Sugar • C12H22O11
– Trinitrotoluene or TNT • C7H5(NO2)3
What makes the compounds?
• NaHCO3
• C2H4O2
• Mg(OH)2
• 3H3PO4
• 2H2SO4
• (NH4)3PO4
• C6H12O6
• 4CaCO3
Chemical Change…
• Chemical Reactions are shown using Chemical Equations
reactants yield product
2H2 + O2 2H2O
Coefficient Subscript
Name the Parts
Chemical Reaction for Photosynthesis:
6CO2 + 6H2O (+ light energy) C6H12O6 + 6O2
Chemical Reactions
• When a chemical reaction occurs the atoms move around to form new substances.
• The same amount of atoms are present before AND after the reaction, they just may be joined with a new kind of atom.
• 2H2 + O2 2H2O
• CH4+2O2 CO2 + 2H2O
H2 + Cl2 2HCl
What is a Mixture?
• A combination of elements and/or compounds that are NOT chemically combined.
• When these substances are mixed together they do not react with each other chemically.
• Each part of a mixture retains its original properties.
Examples:
• Think PIZZA!– Each topping on the pizza retains its original
properties, they are just all mixed together on top of the pizza
• Or Lemonade…– The lemonade powder is still there it has just been
dissolved into smaller pieces within the water – both the powder and water retain their original properties.
Mixtures vs. Compounds
Types of MixturesHomogeneous
MixtureHeterogeneous
Mixture
Same throughout; no specific ratio
required
Varied composition; no specific
ratio required
Can’t “see” the parts, but
parts keep their own properties
Can usually “see” the parts;
parts keep their
properties
Special Types of Mixtures
• Suspensions: particles of a material are dispersed throughout a liquid or a gas but are large enough to settle out. (Can be separated through a filter)
• Colloids: particles are dispersed through out but are not heavy enough to settle out.
• ex. Milk, Mayonnaise or Jell-o
• Solutions: this is a mixture that appears to be a single substance. (all particles are distributed evenly among each other)
Solutions
• a homogeneous mixture of two or more substances
• have two parts: – Solvent: the substance that is present in greater
amount– Solute: the substance that is present in smaller
amount• When Solute enters the solvent, it dissolves,
spreading out evenly in the solvent• Solvents and solutes can be solids, liquids or gases
Examples of Solutions
Solute Solvent ExampleZinc Copper Brass
(Alloy)
Carbon Dioxide Gas
Flavored water
Soft Drink
Ethylene Glycol
Water Antifreeze
Solutions and Concentrations• Concentration is a measure of the amount of
solute dissolved in the solvent
• Described as “dilute” or “concentrated”
• The concentration of a substance can be found:
Concentration = Solute (g) / Solvent (ml)
Is it an…Element, Compound or Mixture?
• HCl (Hydrogen Chloride)• Salad Dressing• CO2 (Carbon Dioxide)• Na (Sodium)• Ocean Water• Ca (Calcium)• H2O ( Pure Water)• Brass• 4CaCO3 (Calcium Carbonate)• Supreme Pizza• Milk
Homogeneous or Heterogeneous?
• Kool-Aid• Salad dressing• Ocean water• Trail mix• Toothpaste• Dinner salad