CHAPTER 6: CHEMICAL NAMES AND FORMULAS Ms. Knick

Compounds  About 100 different elements  Millions of compounds form from them  Naming is essential in chemistry

Two Types of Compounds 1. Ionic Bonds 2. Covalent Bonds

Ionic Compounds  Are formed between metals and nonmetals

Covalent Compounds  Are formed between 2 or more nonmetals  Compound may be formed between two different nonmetals  Compound may be formed between two of the same nonmetals.

Diatomic Molecules  Elements that do not exist alone.  There are seven. (N 2, O 2, F 2, Cl 2, Br 2, I 2 and H 2 )

COMPOUND FORMATION  Elements want to form bonds so that they can achieve eight electrons in their outer most energy level. THIS IS AN OCTET!  The electrons in the outermost level are called valence electrons

Valence Electrons  We can determine the number of valence electrons an element has by the group of the periodic table that the element is in.

 HELIUM is the only exception! Helium is has 2 electrons even though it is in the last group!

IONIC COMPOUND FORMATION  When an atom of a nonmetal takes one or more electron from an atom of a metal so both atoms end up with eight valence electrons  In other words, a nonmetal is gaining an electrons (anion) and a metal is losing electrons (cation).  We can think of ionic bonds as an attraction between positive and negative particles.

Determining Charges of the Periodic Table (WRITE THEM ON YOUR PT)

Writing Formulas for Ionic Compounds: (No transition metals)  Made of metals and nonmetals  Metal always goes first, nonmetal goes second  Name ends in –ide if no polyatomic ion present  Net ionic charge must = zero  If ionic charges are equal in magnitude but opposite in sign, they cancel  If there is a polyatomic ion, put parenthesis around it

Polyatomic Ion  Covalently bonded group of nonmetal elements with a charge. Ex: CO 3 2- NH 4 +

Practice  Calcium nitride  Sodium oxide  Lithium Chloride  Magnesium sulfide  Lithium carbonate  Magnesium sulfate  Calcium phosphate  Aluminum acetate

B. Writing Formulas for Ionic Compounds: (With transition metals)  Same rules as above, but if the element comes from the middle of the periodic table of under the staircase (except for Al), the charge on the metal is indicated in Roman numerals in the name

Practice  Copper (II) nitride  Copper (III) oxide  Iron (II) phosphate  Silver (I) sulfate

C. Naming Ionic Compounds: Those that do NOT contain a transition metal  Name ends in –ide unless there is a polyatomic ion present  Just write the name of the ions you see

Practice  NaBr  CaCl 2  Mg 3 (PO 4 ) 2  Li 2 SO 4

Naming Ionic Compounds: Those that DO contain a transition metal  You must include the charge in the name using Roman numerals  Uncross the subscripts to get that charge  Be careful anytime there is NOT a subscript (or no parenthesis and subscript around a polyatomic ion); consider the charge on the nonmetal to find the charge on the transition metal

Practice  FeBr 2  Cu 2 (CO 3 ) 3  AuCl 3  Pt 3 (PO 4 ) 4

Molecular Compounds Prefix # of Atoms Indicated THE RULES FOR MOLECULAR COMPOUNDS ARE DIFFERENT THAN THOSE FOR IONIC COMPOUNDS Contains only nonmetals!! No ions present- do NOT use charges Prefix system used when naming binary molecular compounds:

A. Writing Formulas for Molecular Compounds  Prefixes tell you the number of each type of atom  Do NOT criss cross any numbers!

Practice  Dichlorine tetrafluoride  Nitrogen triodide  Trisulfur hexafluoride  Carbon monoxide  Tetrabromine hexanitride

B. Naming Molecular Compounds  If there is a single atom of the first element, omit ­mono-  Name ends in –ide

Practice  P 2 O 5  S 2 Cl 6  CO 2  Cl 2 O  CCl 4