Unit 3: Chemical Names and FormulasLearning Intention:Understand how to name and determine the formula of a compound

Journal: Why do you think we are learning this???

Success Criteria:

I can…•State the number of electrons lost or gained in forming an ion•Name each ion and determine if it is an anion or cation•Classify a chemical formula as molecular formula or formula unit

6.1 Bonding

Two Types of Bonding

• Ionic Bonding• Covalent Bonding

Covalent Bonding• Sharing of electrons between 2 or more non-

metals– Forms: Molecular Compounds

Memorize the 7 Diatomic elements shown on page 138 of your text book!!!!

What are Ions? charged atoms that have gained or lost electrons

• Form between ions• Metal + Non-metal

Ionic Bonding

2 types of Ions:• Cations: positively

charged ions, have lost electrons (metals)

• Anions: Negatively charged ions, have gained electrons (non-metals)

• Ions attract one another by electrostatic forces. – Opposite charges attract

Journal (Think/Pair/Share)

• Explain the difference in the two main types of bonding:

6.2 Representing Chemical Compounds

Chemical Formulas• Molecular Formula: shows the number of each atom

present in a molecular compound– What type of bonding can we expect to find in a molecular

compound? (How do you know this?)NH3

• Formula Unit: representation of ionic compounds in lowest whole number ratios– What type of bonding can we expect to find in a formula

unit compound? (How do you know this?)

NaCl

Law of Definite Proportions

• The masses of the elements in a compound are always in the same proportions.

Law of Multiple Proportions• Whenever two elements form more than one

compound, the different masses of one element that combine with the same mass of the other element are in ratios of small whole numbers

Journal

• How are ions formed???• Compare cations and anions???

6.3 Ionic Charges

Naming Rules for Monatomic Ions: ions of a single atom

Cations (positive charged metals )Name of element + ion

Example: Na+ Sodium ionPractice: Ca2+ _______ ____

Anions (negative charged non-metals)Name changes ending to –ide

Example: F- Fluorine → FluoridePractice: S2- ______________

How do you figure out the charge for an ion????

USING THE PERIODIC TABLE!!!• Group 1: loose 1 electron to become cations

with a 1+ charge (Example: Na+)

• Group 2: loose 2 electrons to become cations with a 2+ charge (Example: Sr2+)

• Aluminum (Group 3a): looses 3 electronsAl 3+

Group 4 typically do not form ions.

• Group 7A: gains 1 electronbecome anions with a 1- charge

What is your prediction about how group 5a and 6a will gain electrons?

• Group 6a: gains 2 electronsbecome anions with a 2- charge

• Group 5a: gains 3 electronsbecome anions with a 3- charge

Journal:

Write the formula and the name for the ions formed by the elements:

ClSKCa

Journal:

Write the formula and the name for the ions formed by the elements:

Cl Cl- ChlorideS S2- SulfideK K+ Potassium IonCa Ca2+ Calcium Ion

Transition Metals may form several different ions

You are responsible for knowing that the roman numeral indicates the charge of the given ion.

Roman Numerals You should know:

I = 1 VI = 6II = 2 VII = 7III = 3 VIII = 8IV = 4 IX = 9V = 5 X = 10

Example:

You should know that:• Chromium (II) indicates a Chromium ion with

a charge of 2+, Cr2+

Journal: What is the charge and formula for…. Copper ICopper II

Lead IV

Example:

You should know that:• Chromium II indicates a Chromium ion with a

charge of 2+, Cr2+

Journal: What is the charge and formula for….Copper I : Cu+

Copper II : Cu2+

Lead IV: Pb4+

Polyatomic Ions

• Ions with more than 1 atomExamples: OH- hydroxideNH4

+ ammonium

NO2 – Nitrite SO3 2– Sulfite

NO3 – Nitrate SO4 2– Sulfate

Memorize the name and charge of the polyatomic ions found on page 147 of the textbook!!!!

Practice