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