Lesson 3.05 Ionic Bonding and Writing Formulas 3.05 Ionic Bonding and Writing Formulas Watch the following video about ions: http://bit.ly/YZkOWc Then, draw a line from each word to its correct definition. Ion • An atom or a group of atoms that form a charge by gaining or losing one or more electrons. Monoatomic Ion • An ion that has a positive charge • Two or more atoms bonded together. Can have an overall charge of positive or negative. Anion • An ion that has a negative charge Cation • An ion consisting of one element Polyatomic Ion Practice Determining Charge Watch the video about common charges: http://bit.ly/YZkOWc Download a periodic table with common charges here: http://bit.ly/XrbE70 What is the common charge for: a. Calcium: _____ b. Phosphorus: ____ c. Hydrogen: ____ d. Sulfur: _____ e. Aluminum: ____ f. Iodine: ______ Let’s Write That Formula Ionic Compound Cation & Anion (+ is always written first) How many Overall ions of each charge of element formula you need is unit is zero its subscript Ionic Compounds - Vocabulary • Ionic Bonding – A chemical bond that is due to transfer of electrons between a cation (metal or H) and an anion (nonmetal). • Ionic Compounds - A compound composed of positive and negative ions that are combined in a ratio where the positive and negative charges cancel out. Overall net charge is zero. The cation is always written first. • Formula Unit - The formula of an ionic compound that represents the simplest whole number ratio of ions in the compound. Writing Formula Units (Formulas) – The Basics Example: Write the formula when calcium and phosphorus bond. A. Write each ion • The positive ion is always written first, then the negative ion. B. Determine how many of each ion we need to make the compound neutral. That will be their subscripts. • Subscripts must be the lowest whole number ratio. C. Check your work • Make sure that the net charge of the formula is zero. Writing Formula Units Practice 1) Aluminum and 3) Bromine and Barium Phosphorus 2) Calcium and Lithium 4) Nitrogen and Fluorine Writing Formula Units – Criss-Cross & Reduce Method Write the formula that forms when the following pairs of elements form an ionic bond: 1. Potassium and Nitrogen 3. Magnesium and sulfur 2. Hydrogen and oxygen 4. Strontium and selenium 3.05 Comprehension Check 1. What is the common charge of a magnesium ion? 2. What is the formula that results when chlorine bonds with barium? 3. Identify three atoms that would lose two electrons to empty its valence energy level. 4. What subscripts are needed to complete the formula unit Al_N_? 5. Which of the following forms a cation? a. Br b. Li C. N 6. Which of the following is a possible formula unit? a. KN3 b. I3N c. MgO Thank You! • It has been great working with you for Writing Ionic Compounds! You will use this for the rest of module 3, module 4 and most of segment 2. • Please use our other recorded teaching sessions for the other lessons. Don’t forget that you can use them to review previous lessons too!