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...