Unit 3: Chemical Names and Formulas Learning 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

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?) NH 3 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 ion Practice: Ca 2+ _______ ____ Anions (negative charged non-metals) Name changes ending to –ide Example: F - Fluorine → Fluoride Practice: S 2- ______________

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: Sr 2+ ) Aluminum (Group 3a): looses 3 electrons Al 3+

Group 4 typically do not form ions.

Group 7A: gains 1 electron become anions with a 1- charge What is your prediction about how group 5a and 6a will gain electrons? Group 6a: gains 2 electrons become anions with a 2- charge Group 5a: gains 3 electrons become anions with a 3- charge

Journal: Write the formula and the name for the ions formed by the elements: Cl S K Ca

Journal: Write the formula and the name for the ions formed by the elements: Cl Cl - Chloride SS 2- Sulfide KK + Potassium Ion CaCa 2+ 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 = 1VI = 6 II = 2VII = 7 III = 3VIII = 8 IV = 4IX = 9 V = 5X = 10

Example: You should know that: Chromium (II) indicates a Chromium ion with a charge of 2+, Cr 2+ Journal: What is the charge and formula for…. Copper I Copper II Lead IV

Example: You should know that: Chromium II indicates a Chromium ion with a charge of 2+, Cr 2+ Journal: What is the charge and formula for…. Copper I : Cu + Copper II : Cu 2+ Lead IV: Pb 4+

Polyatomic Ions Ions with more than 1 atom Examples: OH - hydroxide NH 4 + ammonium NO 2 – NitriteSO 3 2– Sulfite NO 3 – NitrateSO 4 2– Sulfate Memorize the name and charge of the polyatomic ions found on page 147 of the textbook!!!!

Practice