Chem 1 Chapter 8 Ionic Bonding Last Updated November 14, 2018

Ionic Bonding Chemical Bond – Force that hold atoms together e- arrangements are involved in chemical bonding and involve orbitals overlapping e- dot structure is used to illustrate chemical bonds Atoms attempt to achieve noble gas configurations

Ions Cation – (+) positively charged Anion – (-) negative charged Monatomic Ions – single charged atom Polyatomic Ions – groups of atoms that is charged and function as a single unit. (See the back of the B&W Periodic Table)

Ionic Bond Force of attraction that holds oppositely charged particles together through the loss and gain of electrons Most Ionic Compounds are called salts Typically involve a metal with a non-metal or polyatomic ion. Lost e- must = gained e- See practice problems pg 217

Examples Magnesium + Chloride Strontium + Phosphorus Boron + Sulfur Hint: Criss-Cross method

Properties of Ionic Compounds Strong Bond Form Crystal Lattice Melting Point, Boiling Point, Hardness  due to strong bonds tend to be high Good conductors of electricity when dissolved in water Form electrolytes Formation of ionic bonds is always exothermic

Lattice energy Energy required to separate 1 mol of ions in ionic cmpd. (Strength holding ions in place) The more negative the lattice energy the stronger the force of attraction Related to the size of the ions bonded (LiCl has higher lattice energy than LiBr since atoms are closer together)

Naming and Formulas Formula Unit  simplest ratio of ions represented in an ionic cmpd. Already defined (monatomic and polyatomic ions) The charge of a monatomic ion is its oxidation number also called oxidation state. Do practice pg 224 and 225

Naming Name cation followed by anion Monatomic cations use element name Monatomic anions use their root name followed by –ide Oxygen is oxide etc. Transition metals often have more than 1 oxidation number and therefore use Roman Numerals When using Polyatomic ions simply name ion

Metals Do not form compounds. with other metals. Mixture of metals is known as an alloy Form metallic bonds which involve delocalized electrons Delocalized electrons are free moving electrons.