1. An Intro CHEMICAL FORMULA

2. COMPOUND: a pure substance made up of two or more elements that are chemically combined Can be broken down into simpler parts by chemical means ELEMENT: a pure substance made up of one type of atom that cannot be broken down by chemical means Recall

3. Short forms used to represent the names of elements Some of the elements were discovered during ancient times hence the Latin names Chemical Symbols Element NameChemical SymbolLatin NameMeaning of Name SilverAgArgentum“silver” SodiumNaNatrium“sodium” PotassiumKKalium“plant ashes” LeadPbPlumbum“lead”

4. Almost all elements exist as atoms however a few exist as MOLECULES MOLECULE: a type of particle that is made up of two or more atoms bonded together Molecule ElementChemical Symbol# of AtomsChemical Formula HydrogenH2H2H2 NitrogenN2N2N2 OxygenO2O2O2

5. A short form for writing the name of a compound using chemical symbols and numbers The chemical symbol is written first followed by a subscript number Chemical Formula

7. Write the chemical formula given the following description:  Hydrogen sulfide is a compound that is composed of two atoms of hydrogen and one atom of sulfur H 2 S Writing Chemical Formula

8. Write the chemical formula for each compound given the following descriptions: a.A compound with one atom of silicon and four atoms of hydrogen b.A compound with three atoms of carbon and eight atoms of hydrogen c.A compound with two atoms of sodium, one atom of carbon and three atoms of oxygen Now You Try…