1. Bonding Between Atoms

2. Bonding Between Atoms Why do atoms form bonds?
To get a stable octet of valence electrons.
Called a “noble gas configuration”

3. Two Major Types of Bonds
IONIC BOND
Metal and Nonmetal
valence e- transferred
COVALENT BOND
All nonmetals
valence e- shared
Crash Course:

4. Changes in Energy Energy is released when bonds form. exothermic
Lower energy = more stable
Exothermic = Bond Forms
Endothermic = Bond Breaks

5. Lewis Dot Diagrams of Atoms
Show valence electrons involved in bonding

6. Lewis Dot Diagrams of Ions
Positive Ions (cations): lose outer shell valence to get stable octet.
Negative Ions (anions): gain electrons to complete outer shell octet.
What are Ions (4:44)

7. Ionic Bonding Happens between metals and nonmetals
What are Ionic Bonds? (1:30)

8. Atoms Become Ions Metals Lose Electrons:
Ex: Mg is 2-8-2
Loses 2 electrons to become Mg+2 2-8
Nonmetals Gain Electrons: usually take top (-) charge
become (–) ion
Ex: Cl is 2-8-7
Gains 1 electron to become Cl

9. Ionic Bond = Electron Transfer
As ions form, an exchange or transfer of electrons happens.
Lithium (metal) 2-1
Fluorine (nonmetal)

10. They transfer enough electrons so that all get a stable octet of valence!
Na before: 2-8-1
Na after: 2-8
Cl before: 2-8-7
Cl after: 2-8-8
Mg before: 2-8-2
Mg after: 2-8
O before: 2-6
O after: 2-8
Ca before
Ca after 2-8-8
Cl before: 2-8-7
Cl after: 2-8-8
(Happens twice!)

11. Electronegativity Difference
Ionic compounds: large differences in atomic EN values ( > 1.7)
Greater EN diff. = more “Ionic Character”.

12. Ex: EN Values Metal Na = 0.9 Nonmetal Cl = 3.2
Nonmetal with higher EN “takes” electron(s) from metal

13. Positively and negatively charged ions form and attract each other due to OPPOSITE CHARGES.
IONIC BOND
Forming Table Salt :6 minutes -
ion
+ ion

14. Ionic compounds have uniform crystalline lattice structure.

15. Can you identify an ionic compound from a covalent?
_____________MgBr2
_____________Ca(NO3)2
_____________P2O5
_____________CO2
_____________Na2S
_____________H20

16. Drawing Lewis Dot Diagrams of Ionic Compounds
Page 7 Bonding Packet

17. Ionic Compounds are Neutral
“Subscripts” show
ratio of ions
Total positive and
negative charges
must balance so the
compound is
electrically neutral.

18. Writing Neutral Ionic Formulas
Write symbols of elements
Write the charges
Criss-Cross charges if necessary to balance the formula
Put parenthesis around polyatomic ions if more than one in formula
Simplify if needed.
Tutorial on writing ionic formulas 9 min

19. Stock System for Naming Ionic Compounds
Binary:
Contain ions of 2 elements
Ex: MgCl2, Al2O3, NaCl

20. Name nonmetal with “-ide” ending.
Naming Binary Ionics
Name metal
Name nonmetal with “-ide” ending.
Note: Name never indicates # of ions
Ex: NaCl, MgBr2, CaO, Al2S3
Writing Ionic Formulas: (3:22)

21. Ternary Ionics: Contain 3 elements
Polyatomic ion present.
Note: Elements inside the polyatomic ion are covalently bonded (all nonmetals).
These compounds contain both ionic and covalent bonds!!
MgSO4

22. Naming Ternary Ionics (with polyatomic) Name Metal Name polyatomic ion
If two polyatomics, name them both
Ex: NaNO3, Ca3(PO4)2, NH4Cl
Ionics with Polyatomic Ions: (3:46)

25. Why does the 3rd compound use a Roman Numeral in it’s name?

26. When to Use a Roman Numeral
Roman numerals are used when the metal can have more than one possible charge.
Roman numeral indicates the charge the metal takes in that compound and must be indicated in the name
Ex: NiBr2 Nickel II Bromide
NiBr3 Nickel III Bromide

27. Name the following ionic compounds:
Fe(NO3)3 ____________________
NaF _________________________
Cu3P ________________________
Al2(SO4)3 ____________________

28. Write the correct formula for:
_____________cobalt III oxide
_____________magnesium sulfide
_____________ lead II nitrate
_____________ calcium phosphate

29. Properties of Ionic Compounds

30. High Melting Point Attraction between ions is very strong.
Requires large amount of
heat energy to separate
ions and make solid melt.
Higher MP than covalents

31. Solubility in Water
Most ionics will dissolve in water, or be “soluble”.
When dissolved in water they are “aqueous”
Ex: NaCl (aq)

32. Water is a “polar molecule”.
Acts like magnet to pull ions apart and into solution.
Ions are now “dissociated” or “hydrated” ions.

33. Conductivity
Ionic compounds conduct when ions are “mobile” or free to move about.
Ionic compounds conduct when:
Molten (melted or liquid) (l)
Aqueous (aq)

34. Molten Ionics can Conduct!

35. Conductivity DO NOT conduct when solid as the ions locked in place.
Most covalents do not conduct

36. Which compound has the highest Melting point?
KCl or SO2
Which substances conduct electricity?
NaCl (s)
CO2 (g)
MgBr2 (l)
C6H12O6 (s)
LiNO3 (aq)

37. Dancing Queen: Song about Ionic vs Covalent Bonding
Crash Course Chemistry: Nomenclature
(only watch first 6 minutes, skip section on naming acids for now)
Dancing Queen: Song about Ionic vs Covalent Bonding
Crash Course: Atomic Hookups