Ionic Bonding Notes 2018-19

These are also called salts or crystals. Ionic Bonds ALWAYS formed between metals and non-metals Transfers electrons to become stable Results from the attractive forces between + and – ions. STRONGEST force BETWEEN elements [METALS ]+ [NON-METALS ]- Lost e- Gained e- These are also called salts or crystals.

Formation of an Ionic Bond When an atom loses or gives a valence electron to another atom, it becomes a (+) ion. This is a CATION. When an atom takes or gains a valence electron from another atom, it becomes a (-) ion. This is an ANION.

Model of Ionic Bonding 1 valence e- 7 valence e- 8 valence e- Cation – Na +1 Anion – Cl -1 1 valence e- 7 valence e-

Ionic Bond

Writing Formulas for Binary Ionic Compounds To write a formula for a binary ionic compound Write the ions that are named in the compound showing their charges. In the formula, list the positive (cation) symbol first and then the negative (anion) symbol Make sure the formula has the lowest whole number ratio. Note: you never write subscript of 1; 1’s are always understood.   One easy way to figure out the formula of an ionic compound is to switch the oxidation number of each ion and use them as the subscripts (without the charge). We call this Drop and Swap DROP +/- signs and SWAP the superscripts to subscripts

Lewis Dot Structure 2+ 1- DROP AND SWITCH THE CHARGES Shows the # of valence elecrons the atom has 2+ 1- What is the charge on Ca? What is the charge on F? How many atoms of Ca and F are needed? DROP AND SWITCH THE CHARGES

Lewis Dot Structure Ca 2+ F- Drop Ca2 F1 Switch Don’t write 1!!! CaF2

Lewis Dot Structure Na and N [ [ -3 +1 [ [ 1+ 3- Drop Na1 N3 Switch +1 [ +1 [ -3 [ Na3N [ [ [ [ [ +1 Don’t write 1!!!

Exampl Ca+2 F-1 CaF2 Na+1 N-3 NaN3 Ex 1: Calcium and Flourine Ex 2: Sodium and Nitrogen ________________________________________________ ________________________________________________ Ca+2 F-1 CaF2 Na+1 N-3 NaN3

The formula must be in the lowest whole number ratio. Ex 3: Write the formula for magnesium and sulfur. ________________________ Ex 4: Write the formula for aluminum and oxygen. ________________________ Mg+2 S-2 Mg2S2 MgS Al+3 O-2 Al2O3

Naming Binary Ionic Compounds; Nomenclature Ionic Compounds are made of a positive ion metal and a negative ion non-metal. Write the name of the metal (cation) first Write the root name of the nonmetal Add “ide” to the root name of the nonmetal Like this: [Na]+ Sodium [Cl]- Chlorine NaCl Sodium Chloride

Ex 1: Magnesium sulfide ZnBr3 zinc bromide K3N potassium nitride Name: MgS _______________________________________ Magnesium sulfide Practice ZnBr3 zinc bromide K3N potassium nitride CaO calcium oxide AlF3 aluminum fluoride