IONIC COMPOUNDS Review Valence electrons electrons in outer
- Slides: 9
IONIC COMPOUNDS
Review • Valence electrons = electrons in outer energy level, participate in chemical bonds • Chemical bond = the force that holds two atoms together • Forming Ions: positive (cation) = formed by losing electrons, negative (anion) = formed by gaining electrons
Octet Rule & Lewis Dot Diagrams • Octet rule : atoms tend to gain, lose, or share electrons in order to acquire a full set (8) valence electrons • Lewis Dot Diagrams: valence electrons places as dots around the element symbol
Forming an Ionic Bond Ions Monatomic Composed of a Single atom Polyatomic Charged group of atoms • Type 1: Binary Ionic compounds = contain only two different elements – Ex: Na. Cl, Mg. Br 2 • Type 2: Polyatomic Ionic compounds = contain polyatomic ions, three or more elements – Ex: Na. OH, NH 4 Cl, H 2 SO 4
Naming Ionic Compounds • 1. Name the cation first. It is just the name of the element. • 2. Name the anion second. – If it is a monatomic anion (only one element) change the ending of the element name to ide. Example: Chlorine = chloride – If it is a polyatomic anion (multiple elements) use the name provided on your blue common ions handout. Example: SO 42 - = Sulfate
Practice • Name the following ionic compounds: – Na. F – KBr – Ag. Cl – KNO 2 – Fe(CN)2 – Mg. S 2 O 3
Writing Ionic Formulas Using the Empirical Formula • Empirical Formula = ratio of ions in a compound simplify to lowest whole #’s • 1. Determine the charge of each ion. • 2. Always write the cation (positive ion) first. • 3. Write the anion (negative ion) second. • 4. Determine how many of each ion you need to have the charges balance. (criss-cross method) • 5. Use parentheses around the ions to separate if necessary. • 6. Write the amount of each ion you need as a subscript after the parenthesis.
Practice • Write the formulas for the following ionic compounds: – Calcium chlorate – Potassium iodide – Aluminum bromide – Aluminum carbonate – Sodium sulfate – Magnesium phosphate
Counting Atoms • How do you determine the number of atoms of each element in an ionic compound? – Multiply the number of atoms in the ion by the number of ions in the compound. Al 2(Cr. O 4)3