MATTER MIXTURES Physical change PURE SUBSTANCES MECHANICAL MIXTURES SOLUTIONS ORDINARY MECHANICAL MIXTURES SUSPENSIONS COLLOIDS Chemicalchange ELEMENTS COMPOUNDS
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.
What is a pure substance? A pure substance, by definition, is an element or a compound. Salt, Coal, Gold
Pure Substance Pure Substance Compound Element
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.
Chemistry Vocabulary H C O Fe Cl Ag Cu Ba Pb 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
Zinc, copper, lead, carbon, sulfur Elemental Samples Zinc, copper, lead, carbon, sulfur
What is a compound? A compound is a substance that is made from the atoms of two or more elements that are chemically bonded.
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.
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.
Sodium
Sodium metal Soft, can be cut with a knife Shiny Good conductor of electricity Very reactive
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
Chlorine gas
Chlorine gas Greenish gas Poisonous Heavier than air
Sodium in chlorine gas
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.
Samples of Other Compounds Sucrose (table sugar), Sodium Chloride, Water, Copper(II) sulfate
Colored Compounds Cobalt(II) chloride, Iron(II) sulfate, Potassium dichromate, Potassium chromate, Nickel(II) nitrate, copper(II) sulfate