Chemistry - Matter Unit

1
SUSPENSIONS
ORDINARY MECHANICAL MIXTURES
COLLOIDS
ELEMENTS
COMPOUNDS
2
What is a pure substance?

• A pure substance has a definite composition
  (proportion).
• The composition of a substance will have the same
  percent of elements no matter where the sample
  was obtained.
• Water from the Atlantic Ocean and water from the
  Pacific Ocean (once cleaned up) will have the
  same composition of hydrogen to oxygen.

3
What is a pure substance?

• A pure substance, by definition, is an element or
  a compound.
• Salt, Coal, Gold

4
Pure Substance
Pure Substance
Compound
Element
5
What is an element?

• A substance that cannot be decomposed any farther
  by simple chemical means
• An element has a definite composition. Gold from
  South Africa is the same, when purified, as a
  sample from California.

6
Chemistry Vocabulary

• A Symbol is a representation of an element.
• One or two letters may be used.
• The first letter is upper case while the second
  is lower case.

H C O Fe Cl Ag Cu Ba Pb
7
Elemental Samples

• Zinc, copper, lead, carbon, sulfur

8
What is a compound?

• A compound is a substance that is made from the
  atoms of two or more elements that are chemically
  bonded.

9
What is a compound?

• A compound is a substance that cannot be
  decomposed any farther by simple physical means.
• A compound is made up of two or more elements
  chemically combined.

10
What is a compound?

• A compound no longer has the properties of its
  constituent elements.
• Table salt, NaCl or sodium chloride, is a
  compound of the element sodium and the element
  chlorine.

11
Sodium
12
Sodium metal

• Soft, can be cut with a knife
• Shiny
• Good conductor of electricity
• Very reactive

13
Sodium in water

• Observe the reaction
• What is the color of the solution
• Do you observe any gas produced
• Is it a chemical or physical reaction?
• Does the reaction terminate immediately

14
Chlorine gas
15
Chlorine gas

• Greenish gas
• Poisonous
• Heavier than air

16
Sodium in chlorine gas
17
Properties of Sodium chloride ( NaCl)

• Sodium chloride dissolves in water rather than
  reacts with water.
• Sodium chloride is a white solid, not a poisonous
  green gas.
• Sodium chloride is its own substance with its own
  properties, not those of either sodium or
  chlorine.

18
Samples of Other Compounds

• Sucrose (table sugar), Sodium Chloride, Water,
  Copper(II) sulfate

19
Colored Compounds

• Cobalt(II) chloride, Iron(II) sulfate, Potassium
  dichromate, Potassium chromate, Nickel(II)
  nitrate, copper(II) sulfate