Transcript Ch 7 Flipped Notes Part 1

Chemical Formulas and
Chemical Compounds
Chapter 7
Molecular and Ionic Compounds
Ionic
Compound
Molecular
(Covalent)
Compound
Composition
metal-nonmetal
nonmetal-nonmetal
Smallest unit
formula unit
molecule
Smallest
particles
ions
atoms
Significance of Chemical Formulas
Subscripts—refer only to the atom
(or atoms in parentheses) that come
BEFORE it
Al2(SO4)3
 NOTE: multiply subscripts outside
parentheses with the subscripts inside
them to get the total number of each atom

Naming Monatomic Ions
Monatomic: made up of only ONE atom
 All group A (main group) monatomic
CATIONS: simply name the name of the
element and add “ion” to it
 All monatomic anions: change ENDING to
“-ide” (NOTE: most elements lose a significant
amount of their name. Ex. sulfur  sulfide;
phosphorus phosphide; oxygen  oxide)

Naming Monatomic Ions Cont…

Stock System: uses roman numerals to indicate
the positive charge an ion has
Copper (II)

means
Cu+2
USE THIS SYSTEM ONLY WHEN NAMING
TRANSITION METAL IONS
Exceptions: Tin (Sn) and Lead (Pb) also get the
roman numeral
Naming Monatomic Ions Cont…
Ion
Name
Stock System
Fe2+
ferrous
iron(II)
Fe3+
ferric
iron(III)
Ag1+
silver
Silver(I)
Pb2+
plumbous
lead(II)
Pb4+
plumbic
lead(IV)
Polyatomic Ions

Some Transition Metal naming rules:

“ic” ions have a greater (+) charge than “ous” ions
• Ex. ferric (Fe3+) and ferrous (Fe2+)

Polyatomic ions—made up of two or more atoms
(charge applies to the entire species)

for anions:
• hypo-anion-ite < anion-ite < anion-ate < per-anion-ate in
terms of O’s in the ion (all will have the same NEGATIVE
charge)
• Ex. ClO-1
ClO2-1
ClO3-1
ClO4-1
Hypochlorite Ion

Chlorite Ion
Chlorate Ion
Perchlorate Ion
NOTE: not all “ate” ions will have “ite” ions
Rules for Ionic Formulas

All Ionic Compounds are Neutral

This means the total Charge must be ZERO
CATIONS + ANIONS = ZERO
All Ionic Compounds start with the cation
(Positive Ion) first.
 All Ionic Compounds are in their lowest
whole number ratio.

Writing formulas for Ionic
Compounds
If you are given the name of an ionic compound, you need
to follow these rules in order to write its formula:
1. Write out the formula (with charge) of the cation (first part
of name)
2. Write out the formula (with charge) of the anion (second
part of name)
3. The positive charges must cancel out the negative
charges (criss-cross the charges)
4. The formula must show the LOWEST whole-number
ratio of cations to anions.
** You CANNOT change the formula of POLYATOMIC
IONS! Add parenthesis if there is more than one.
Example…
Sodium and Oxygen
1.
Na
O
2.
Na+1
O-2
3.
Na2O
4.
Identify the symbol
for each element
Find the charge for
each based on
group
Criss – Cross the
number without the
charge
Check to make sure
all rules have been
followed
Example
Leave 1/2 page for Class Notes
and Examples:
Class Examples
1.
Calcium
and
2.
Aluminum
and
3.
Gallium
4.
Potassium and Sulfite
5.
Ammonium and Phosphorus
and
Chlorine
Sulfur
Phosphate
Nomenclature for Ionic Compounds
To name an ionic compound:
* Identify the compound as ionic (m-nm or
polyatomic ion present)
* Identify the cation (first ion). Ignore how many
are present.
*Identify the anion (second ion). Ignore how many
are present.
* You MUST be able to recognize polyatomic
ions by sight.
* Name is: cation anion
• If the cation is a TRANSITION METAL you will
need a roman numeral
The name must identify which ion it is,
because transition metals have multiple
Oxidation Numbers (Charges)
Name is: cation ( ) anion
*Work backwards to figure out the charge.
Leave 1/2 page for Class Notes
and Examples: