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NaCl and why is it called Sodium chloride ??. When you read the labels of things you consume, it might be a good idea to kind of know what those names mean!! How do they write and name compounds? Let’s find out. Chemical Bonding: Ch. 8.
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NaCl and why is it called Sodium chloride ?? • When you read the labels of things you consume, it might be a good idea to kind of know what those names mean!! • How do they write and name compounds? • Let’s find out.
Chemical Bonding: Ch. 8 Or, what atoms will do to achieve a noble gas configuration (stable octet).
There are 4 types of Bonds in this world of ours: • Ionic – bonds between a Cation & Anion. • Covalent – let’s share electrons. • Metallic – like alloys. • Van der Waals (Intermolecular Forces). These are very weak.
Covalent or Molecular – very creative stuff Metallic bonds: “sea of electrons” or decentralized e’s. Ever wonder how electricity is conducted? This is it! Ionic: Lattice Structures, very organized
Two ways atoms can achieve stability • 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 MgCl2 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 H2O CO2 • Composed of two or more Non-metals !!
Properties of Ionic Bonds • The stronger of the two. How do we know? Melting Pt. of NaCl = 801oC Melting Pt. of H20 = 0oC • Responsible for all the crystals in the world, p. 218. • They form very organized shapes called Lattices. The energy to break up the Lattice is the Lattice Energy. Then you’ll like Ionic Bonds !!
If you like these ……. Rubies Sapphires Garnets
Here’s a good Deductive Question. • Page 220 • Why is the Lattice Energy for NaCl (769kj) less than MgO (3795kj)? • Na+Cl- vs. Mg 2+O2- • MgO has the greater +/- attraction! • Oh, I get it !!
Ionicallybonded 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 (858oC) 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? • NaCl sodium chloride • MgO magnesium oxide • Ca3(PO4)2 calcium 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! • Ternary ionic: made of 3 or more! Examples: NaCl MgO Ca3(PO4)2 binarybinaryternary
Binary • First write the correct formula by balancing the ionic charges! Na+1 + Cl-1 NaCl Ca+2 + S-2 CaS Al+3 + O-2 Al2O3
Write the Name • Two Words • Write the name of the Cation first (always!) • Write the “root” of the Anion oxygen is ox; chlorine is chlor . . . • End the anion name with the suffix – ide • Ex: NaCl is sodium chloride !
Try these !Write the correct formula and name • Li + O • Ca + F • K + Cl Li2O = lithium oxide CaF2 = calcium fluoride KCl = potassium chloride
Stop Here • Turn in today: • 53,57,64 & 67 at end of ch.8 in your text.
Homework Assignment • 53,57,64,67,72,74,75,78,79,86 & 88. • I will combine this chapter (8) with the next chapter (9) into one exam.
Let’s go from the name to the formula! • Barium sulfide • Copper(II)chloride • Iron(III)oxide What’s with the Roman Numeral stuff?? BaS CuCl2 Fe2O3 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 • CuCl2 • ZnF2 • SnO2
Write the Formula &Name Li + Br Ag + Cl Mg + S Ca + Se K + Ar Fe(III) + S Write the Formula Cesium bromide Chromium(III) sulfide Lithium iodide Barium phosphide Aluminum nitride Boron oxide Do the following on a sheet of paper: