CHAPTER 6: CHEMICAL NAMES AND FORMULASMs. 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.

CO2 NH3 H2O

O2 N2 H2

Diatomic Molecules Elements that do not exist alone. There are seven. (N2, O2, F2, Cl2, Br2, I2 and

H2)

SUPE

R

7

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 nonmetalsMetal always goes first, nonmetal goes secondName ends in –ide if no polyatomic ion presentNet ionic charge must = zeroIf ionic charges are equal in magnitude but

opposite in sign, they cancelIf there is a polyatomic ion, put parenthesis

around it

Polyatomic Ion Covalently bonded group of nonmetal

elements with a charge.

Ex: CO32- NH4

+

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

PracticeNaBr

CaCl2

Mg3(PO4)2

Li2SO4

 

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

PracticeFeBr2

Cu2(CO3)3

AuCl3

Pt3(PO4)4

Molecular Compounds

Prefix# of Atoms Indicated

  1

  2

  3

  4

  5

  6

  7

  8

  9

  10

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 P2O5

S2Cl6

CO2

Cl2O

CCl4