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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
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