1. Bonding Between Atoms

2. Why do Atoms Form Bonds? To get a stable octet of valence electrons.
Called a “noble gas configuration”
IONIC BOND = valence e- transferred
COVALENT BOND = valence e- shared

3. Changes in Energy Energy is released when bonds form. (exothermic)
Results in lower energy, more stability
Know example…

4. Lewis Dot Diagrams of Atoms
Show valence electrons that are involved in bonding

5. 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.

6. Ionic Bonding Happens between metals and nonmetals
Forming Table Salt :6 minutes

7. 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

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

9. Electronegativity Difference
Atoms in ionic compounds
have large differences in their EN values ( > 1.7)
The greater the EN difference, the
more “Ionic Character”.

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

11. Positively and negatively charged ions form and attract each other due to OPPOSITE CHARGES.
Attraction forms an
IONIC BOND -
ion
+ ion

12. Ionic compounds have a uniform crystalline lattice structure.

13. Can you identify an ionic compound from a covalent?

14. Drawing Lewis Dot Diagrams of Ionic Compounds
Do Page 7 in Bonding Packet

15. Writing Ionic Formulas

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

17. 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

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

19. Naming Binary Ionics
Name metal
Name nonmetal with “-ide” ending.
Ex: NaCl, MgBr2, CaO, Al2S3

20. Ternary: Contain 3 elements
Polyatomic ion present.
Elements inside the polyatomic ion are covalently bonded (all nonmetals).
Thus these compounds contain both ionic and covalent bonds!!
Ex: NaNO3, Ca3(PO4)2, NH4Cl

21. Naming Ternary Ionics (with polyatomic)
Name Metal
Name polyatomic ion
If two polyatomics, name them both

22. 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

23. Crash Course Chemistry: Nomenclature
(only watch first 6 minutes, skip section on naming acids for now)

24. Properties of Ionic Compounds

25. High Melting Point Attraction between the ions is very strong.
Requires a lot of heat
energy to separate
ions and make solid
crystal melt.

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

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

29. Conductivity
Ionic compounds conduct when ions are “mobile” or free to move about.

30. Conductivity Ionic compounds conduct when: Molten (melted/liquid) (l)
Aqueous (aq)
Note: They DO NOT conduct
when solid as the ions are locked
in place.

31. Dancing Queen: Song about Ionic vs Covalent Bonding
Crash Course: Atomic Hookups