1. Chemical Bonding
Chemistry
Unit 6

2. How do atoms make compounds?EQ
How do atoms make compounds?

3. Review- Oxidation numbers
Write the Lewis Dot Diagram and give the oxidation number of the following. S O Ca Na P Al

4. Bonding
Chemical bond- hold two or more atoms held together to make each have 8 valence electrons
Who they bond with is determined by their oxidation number
Atoms gain, lose, or share electrons to get 8 valence electrons (Octet Rule)

5. Compounds are always neutral
IMPORTANT
Compounds are always neutral
For ex-NaCl
Na = oxidation #= 1+ Cl = oxidation # = 1- Total charge on NaCl = 0= neutral For ex- CaF2 Ca= oxidation # = 2+ F = oxidation # = 1- F2 = 2- Total charge = 0 = neutral

6. Types of bonds
Ionic- cation (metal) and anion (nonmetal) bond based on oxidation number; metal loses electrons, nonmetal gains electrons
Covalent- nonmetal and nonmetal share electrons
Metallic- two metals share electrons

7. The number of electrons an atom has gained, lost or shared
Oxidation number
The number of electrons an atom has gained, lost or shared
STABLE
Tells about
To become

8. Group Number Oxidation number
Oxidation numbers of elements can be found by GROUP #s on the periodic table.
Group Number
Oxidation number
Group # 1 1+
Group # 2 2+
Group # 13 3+
Group # 14 4+
Group # 15 3-
Group # 16 2-
Group # 17 ( halogens) 1-
Group # 18 ( Noble Gases)

9. Ones and Twos When do chemical bonds form?
Who is more reactive: alkali metals or alkaline earth metals?
Give the number of valence electrons for oxygen, sulfur, arsenic, phosphorous, and bromine.
Why does calcium form a +2 ion instead of a +3 ion?

10. Is a compound made up of 2 elements
Binary Compound
Is a compound made up of 2 elements Na Cl
For ex- NaCl is made up of 2 elements

11. Review- Write the answers in your notebook
Which of the following compounds are Binary Compounds?
KCl
H2SO4
CO2 KI
PO4
P2O5
CaSO4

12. Types of Bonds Purpose- to make atoms more stable
How e- are distributed determines the type of bond
Ionic- electrical attraction b/t cation & anions
Covalent- sharing of e- pairs b/t two atoms

13. Vocab Cations- positive ions Anions- negative ions
Electronegativity- the ability of an atom to attract electrons; used to estimate if the bond is ionic or covalent
Diatomic- two of the same (the gases)

14. Ionic Bonding & Ionic Compounds
Chap 8

15. Basics of Ionic Bonds Bonding of metal + nonmetal
WS- Types of Chemical bonds
Transfer of electrons
Metal loses e- (cation) nonmetal gains e- (anion)
Ionic charges cancel in the bonding

16. Formula unit- the smallest formula for an ionic compound
Ex: table salt is composed of lots of atoms, but the formula is written NaCl
The ratio of ions in the formula unit depends upon the oxidation numbers on the atoms

17. Characteristics of Ionic Bonds
Lattice energy- the energy required to form an ionic compound (bond energy is specific to breaking a bond)
Negative values indicate that energy is released
Positive values indicate that energy is absorbed

18. Properties of Ionic vs. Molecular Compounds
*very strong bond b/c very strong attractive force
High melting point (do not vaporize at room temp)
High boiling point
Hard & brittle crystal lattice: ordered repetition of pos & neg charges
Good conductors (if they can dissolve in water)
Made of metal & nonmetal
*Strong bond, but weak attractive force
Low melting point (most are gaseous at room temp)
Low boiling point
Usually a gas at room temp, soft solids, some liquids
Poor conductors
Made of nonmetals

19. Polyatomic Ions
Polyatomic Ion- a charged group of covalently bonded atoms; covalently bonded, yet behaves like an ion
Pg 224 Table 8-6

20. Summary
Answer the EQ- share your answer with the person next to you AFTER you write (that means write THEN talk)

21. Molecular Compounds
Chap 9

22. Molecule- neutral group of atoms covalently bonded together
Molecular compound- many molecules bonded together
Electrons are shared b/t atoms in a covalent bond so they all have 8 valence electrons

23. Lewis structures- demonstrate covalent bonding
Draw the elements symbol
Draw the number of valence electrons

24. Practice- Lewis Structures
Pg 244 #1-5
Pg 247 #12

25. Ionic or Covalent?
If two of the same atom are bonded together, then it is completely covalent
Nonpolar covalent- bonding e are shared equally; 0-5% ionic character or EN difference
Polar covalent- uneven sharing of e; 5-50% ionic character or EN difference

26. Naming Molecular Compounds
(prefix)1st element + (prefix) root 2nd element Ex. P2O5 diphosphorous pentoxide

27. # of Atoms Prefix
mono
2 di
3 tri
4 tetra
5 penta
6 hexa
7 hepta
8 octa
9 nona
10 deca

28. Ionic or Covalent?
EN values < 1.7 is a covalent bond b/c the bond has 50% or less ionic characteristics
The bond is ionic if the EN difference is > 1.7
Anions attract e-
Cations give away e-

29. Practice
Pg 249 # 13-17

30. Compare and contrast ionic and covalent bonds
Ionic bonds
__________
___________
Covalent bonds
________
_________

31. Naming Acids
Oxyacids- contain hydrogen and an oxyanion (PI with oxygen in it)
Replace –ate with –ic
Replace –ite with –ous
Ex. HNO3 nitrate  nitric acid
Binary Acids- contains H and one other element
Hydro + element + ic
Ex. HCl = hydrochloric acid

32. Practice- Naming Acids
Pg 250 # 18-22

33. Know the symbols for partial negative charge on the covalent bond (δ-) and partial positive charge (δ+)
Know how to tell the bond type based upon EN values