Groundhog Day is
Sunday!
Have fun watchin
g the Super Bowl!
Thursday, Jan. 30th: “A” DayFriday, Jan. 31st: “B” Day
AgendaCollect lab: “Is it an Ionic Compound?”ACT practice questions (Atomic Structure/Ion Energy)Start Sec. 5.3: “Names/Formulas of Ionic
Compounds”In-Class/Homework:
“What is an Oxidation Number?”“How are Chemical Compounds Named?” “Naming Ionic Compounds” Concept Review
Lab: “Is it an Ionic Compound?”Make sure your table of contents is updated
with this lab.Don’t forget the reflection statement!Put your lab folder back in the bin to be
graded.
ACT Practice QuestionsThe science portion of the ACT is
really a test of your critical thinking skills.All the information you need to answer the
questions should be provided in the passage, chart, graph, etc. that you are given.
Read through the sample passage and answer the questions.
YES, you do need to do this and YES, it WILL be graded!
When you’re finished, turn it in and pick up today’s notes…
Sec. 5.3: “Naming Ionic Compounds”Salts that are made of a simple cation and a
simple anion are known as binary ionic compounds.
The adjective binary means that the compound is made up of just two elements.
Examples:
NaCl Binary = MgO
Rules for Naming Simple CationsRemember, metals LOSE electrons to form
cations. (+ ions)Simple cations take their names from the names
of the elements.For example, K+ is the potassium ionCa2+ is the calcium ion
What is the name of Li+? lithium ion
What is the name of Sr2+?strontium ion
Rules for Naming Simple CationsWhen an element forms two or more stable ions
(transition metals) the ion name includes roman numerals to show the charge.
For example, copper can form either Cu+ or Cu2+ (see handout)
Cu+ = copper(I) ionCu2+ = copper(II) ion
This is read as “copper one ion” and “copper two ion”
Rules for Naming Simple AnionsRemember, non-metals GAIN electrons to form anions.
(- ions)The name of a simple anion is also taken from the
name of the element, but the ending is changed to -ide.
For example, Cl is the chloride ionS2- is the sulfide ion
What is the name of O2-?
oxide ionWhat is the name of N3-?
nitride ion
“What is an Oxidation Number”An oxidation number is simply the charge on the ion.An oxidation number can be either positive (cation) or
negative (anion).What are the oxidation numbers of the following
ions?Fe3+
3+Cu+
1+
The Names of Ions Are Used to Name the Ionic Compound
Now that you know how to name the simple cations and anions, you can name the binary ionic compound.
The name of a binary ionic compound is made up of just two words: the name of the cation followed by the name of the anion.
+
The Names of Ions Are Used to Name the Ionic Compound
Name the following ionic compounds:1. NaCl
sodium chloride2. ZnS
zinc sulfide3. K2O
potassium oxide 4. FeO (be careful!)iron (II) oxide
5. Mg3N2
magnesium nitride
Writing Ionic FormulasIn an ionic compound, the positive charges of
the cations need to equal the negative charges of the anions. (electrically neutral)
In sodium chloride, the sodium ion has a 1+ charge and the chloride ion has a 1- charge, so one Na+ and one Cl- will add up to a total charge of zero. Na+ Cl-
NaClThe formula for sodium chloride is written as
NaCl to show this one-to-one ratio of ions.
Writing Ionic Formulas
In zinc sulfide, the zinc ion has a 2+ charge and the sulfide ion has a 2 charge, so one Zn2+ and one S2- will add up to a total charge of zero.
Zn2+ S2-
ZnSThe formula for zinc sulfide is written as ZnS to
show this one-to-one ratio of ions.
Ionic Compounds Must Have no Overall ChargeIn some ionic compounds, the charges on the
cation and anion are different.For example, in magnesium nitride, the
Mg2+ ion has two positive charges, and the N3− ion has three negative charges.
The cations and anions must be combined so that there are the same number of negative charges and positive charges.
+ = 0
Compounds Must Have no Overall Charge
In order for the overall charge to be zero, three Mg2+ cations are needed for every two N3 anions.
Mg2+ N3-
Mg3N2
Subscripts are used to show the number of ions.
Example #1
Write the chemical formula for the ionic compound sodium nitride.
Na+ N3-
Na3NThree Na+ cations are needed to balance out the N3-
anion to make the overall charge of sodium nitride equal to zero.
Example #2
Write the chemical formula for the ionic compound aluminum oxide.
Al3+ O2-
Al2O3
Two Al3+ cations and three O2- anions are needed to make the overall charge of aluminum oxide equal to zero.
Hints for writing ionic formulas
1. Find the charges on the cation and anion.2. If the metal is a transition metal, look at the
table to find the possible charges. When naming it, be sure to include a roman numeral in ( ) to indicate the charge on the cation.
3. Write the formula so that the charges balance out to zero.
PracticeWrite the formulas for the following compounds:1. Chromium (II) oxide
CrO2. Zinc bromide
ZnBr2
3. Sodium iodideNaI
4. Iron (III) oxideFe2O3
5. Aluminum bromideAlBr3
In-Class/Homework1. “What is an Oxidation Number”2. “How are Chemical Compounds Named?3. “Naming Ionic Compounds”
If you finish early, work on the concept review
We will finish this section next time...
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