Chemical Bonding: Ch. 8 Or, what atoms will do to achieve a noble gas configuration (stable octet).

Two ways atoms can achieve stability Lose or Gain electrons: Lose or Gain electrons: Na +1 (loses 1 electron) Cation Cl -1 (gains 1 electron) Anion Then the oppositely charged ions attract and you get what’s called an IONIC BOND. Other examples: KCl MgO MgCl 2 Composed of a Metal & Non-metal !!

Another way is to “share” electrons Bonds created by sharing are called: Covalent Bonds The electronegativity of the atoms is not strong enough to take an electron (can’t pay the ionization energy). Examples: HCl H 2 O CO 2 Composed of two or more Non-metals !!

Properties of Ionic Bonds  The stronger of the two. How do we know? Melting Pt. of NaCl = 801 o C Boiling Pt. of H 2 0 = 100 o C Boiling Pt. of H 2 0 = 100 o C  Responsible for all the crystals in the world, p  They form very organized shapes called Lattices. The energy to break up the Lattice is the Lattice Energy.

Here’s a good Deductive Question. Page 220 Why is the Lattice Energy for NaCl (769) less than MgO (3795)? Na + Cl - vs. Mg 2+ O 2- MgO has the greater +/- attraction! Oh, I get it !!

Ionically bonded compounds dissolve in water nicely. Solutions: homogenous mixtures Ionic compounds like NaCl dissolve in water and create solutions called: ELECTROLYTES Electrolytes are solutions that conduct electricity !! Let’s see.

Let’s see if you can answer this!! Why is the Melting Point for the compound KF (858 oC) greater than that of KI (681oC). Answer: What is common between them? The valence electron for F is in level 2; for I, it’s level 5 (farther away and easier to break the bond!).

Now, how do you write and name formulas for Ionic compounds? 1. N aClsodium chloride 2. M gOmagnesium oxide 3. C a3(PO4)2calcium phosphate Here’s the system. We want to be able to write a formula for a compound, and then name it. And, we want to be able to write a formula from the name of a compound.

Two kinds of Ionic compounds Binary ionic: made of 2 elements! Binary ionic: made of 2 elements! Ternary ionic: made of 3 or more! Ternary ionic: made of 3 or more!Examples: NaClMgOCa 3 (PO 4 ) 2 binarybinaryternary

Binary First write the correct formula by balancing the ionic charges! First write the correct formula by balancing the ionic charges! Na +1 + Cl -1  NaCl Ca +2 + S -2  CaS Al +3 + O -2  Al 2 O 3

Write the Name Two Words Two Words Write the name of the Cation first (always!) Write the name of the Cation first (always!) Write the “root” of the Anion Write the “root” of the Anion oxygen is ox; chlorine is chlor... End the anion name with the suffix – ide End the anion name with the suffix – ide Ex: NaCl is sodium chloride ! Ex: NaCl is sodium chloride !

Try these ! Write the correct formula and name Li + O  Li + O  Ca + F  Ca + F  K + Cl  K + Cl  Li 2 O = lithium oxide CaF 2 = calcium fluoride KCl = potassium chloride

Let’s go from the name to the formula! Barium sulfide Copper(II)chloride Iron(III)oxide What’s with the Roman Numeral stuff?? BaSCuCl 2 Fe 2 O 3 Can you figure it out based on the formula??

The “transition elements” have more than one possible charge. So, how do we know if Fe (iron) is +2 or +3 Answer: the Roman Numeral Old system for these multivalence elements was Fe +2 = ferrous & Fe +3 = ferric Sn +2 = stannous & Sn +4 = stannic Don’t panic! The Roman Numeral makes it much easier. Iron(II) means Fe +2

Let’s try that again! Copper(II)chloride Zinc fluoride Tin(IV)oxide CuCl 2 ZnF 2 SnO 2

Do the following on a sheet of paper: Write the Name 1. Li + Br 2. Ag + Cl 3. Mg + S 4. Ca + Se 5. K + Ar 6. Fe(III) + S Write the Formula 1. Cesium bromide 2. Chromium(III) sulfide 3. Lithium iodide 4. Barium phosphide 5. Aluminum nitride 6. Boron oxide