1. Comparison of Properties Ionic Compounds Covalent Compounds Metals
Chemical Bonding
Comparison of Properties
Ionic Compounds
Covalent Compounds
Metals

2. What is a chemical bond?
An attractive force that holds two atoms together
Can form by
The attraction of positive ion to a negative ion or
The attraction of the positive nucleus of one atom and the negative electrons of another atom

3. Bond
the interaction between two or more atoms that allows them to form a substance different from the independent atoms.
involves the outer (valence) electrons of the atoms.
These electrons are
transferred from one atom to another or shared between them.

4. Chemical Bond Energy Considerations
A chemical bond forms when it is energetically favorable
when the energy of the bonded atoms is less than the energies of the separated atoms.
Al + I2

5. Bonding
Chemical compounds are formed by the joining of two or more atoms.
A stable compound occurs when the total energy of the combination has lower energy than the separated atoms.
The bound state implies a net attractive force between the atoms ... a chemical bond.

6. Energy Changes in Bonding
When bonds are formed, energy is released.
Demonstrations:
Formation of an Ionic Compound: Mg + O2
Formation of a Molecular Compound: S + O2

7. Breaking Bonds
In order to break bonds energy must be added, usually in the form of heat, light, or electricity.
Demonstration: Electrolysis of water
Demo: Decomposition of Nitrogen Triiodide

8. Three Types of Bonding
Ionic
Metallic
Covalent

9. Chemical Bonds In chemical bonds, atoms can either transfer or
share their valence electrons.

10. When atoms transfer electrons Ionic Bonds
When one or more atoms lose electrons and other atoms gain them in order to produce a noble gas electron configuration, the bond is called an ionic bond.

11. Metals
Nonmetals

12. Ionic Bonds Part 1 Part 2 Part 3
Part 2
Part 3

13. Ion Formation
All of the elements in Group I have one electron in their outermost energy level.
All of these elements can lose that one valence electron.
These atoms become cations with a positive one charge.

14. Elements in Group II have two electrons in their outermost energy level.
So, when these elements lose electrons, they lose two electrons and take on a positive two charge.

15. Anions Nonmetals tend to gain electrons.
The halogens - fluorine, chlorine, bromine, and iodine - have a strong attraction for electrons.
Their outermost energy levels are almost full. There is only room for one more electron in the outer energy levels for each of those atoms. Consequently, the elements fluorine, chlorine, bromine, and iodine will gain one electron, and become anions with a negative one charge.
Oxygen, sulfur, and the other elements in that family will gain two electrons.
In the next group over, nitrogen, phosphorus and arsenic can take on three electrons.

16. +1 +2 +3 -3 -2 -1

17. Ionic Nomenclature Naming Ionic Compounds Video of the Process

18. Ionic Compounds Made of cations and anions Metals and nonmetals
The electrons lost by the cation are gained by the anion
The cation and anions surround each other
Smallest ratio of ions in an ionic compound is a FORMULA UNIT.

19. K+1 Ca+2 Cations Positive ions Formed by losing electrons
More protons than electrons
usually Metals
K+1
Has lost one electron
Ca+2
Has lost two electrons

20. F-1 O-2 Anion A negative ion Has gained electrons Non metals
Charge is written as a super script on the right.
F-1
Has gained one electron
O-2
Has gained two electrons

21. Formula Unit
The smallest whole number ratio of atoms in an ionic compound.
Ions surround each other so you can’t say which is hooked to which

22. Name these
Na+1
Ca+2
Al+3
Fe+3
Fe+2
Pb+2
Li+1

23. Write Formulas for these
Potassium ion
Magnesium ion
Copper (II) ion
Chromium (VI) ion
Barium ion
Mercury (II) ion

24. Naming Anions
Change the element ending to – ide
F-1 Fluorine

25. Name these
Cl-1
N-3
Br-1
O-2
Ga+3

26. Write these
Sulfide ion
iodide ion
phosphide ion
Strontium ion

27. Write these
Sulfide ion
iodide ion
phosphide ion
Strontium ion

28. Binary Ionic Compounds
Binary Compounds
2 elements.
a cation and an anion.
To write the names just name the two ions.
Easy with Representative elements
Groups 1, 2, 13
NaCl = Na+ Cl- = sodium chloride
MgBr2 = Mg+2 Br- = magnesium bromide

29. Naming Binary Ionic Compounds
Write the names of the following
KCl
Na3N
CrN
Sc3P2
PbO
PbO2
Na2Se

30. Writing Formulas Given the name write the formula
The charges have to add up to zero
Write down each ion with charges
Make the charges equal by adding subscripts
Put polyatomic ions in parentheses if you need more than one of them

31. Writing Formulas Example
Write the formula for calcium chloride.

32. Molecular (Covalent) Substances

33. Covalent Bonds
involve the sharing of a pair of valence electrons by two atoms
Such bonds lead to stable molecules if they share electrons in such a way as to create a noble gas configuration for each atom

34. Covalent bonding can be visualized with the aid of a Lewis Structure

35. Naming Covalent Molecules
Nonmetal nonmetal
Use the prefix to indicate the number of atoms present

36. Prefix nonmetal1 prefix nonmetal2

37. Metals and Metallic Bonding
Typical Properties of Metals
Malleable
Ductile
Good Conductors of Heat and Electricity
Generally high melting and boiling points

38. Metallic Bonds
The properties of metals suggest that their atoms possess strong bonds
yet the ease of conduction of heat and electricity suggest that electrons can move freely in all directions in a metal
The general observations give rise to a picture of "positive ions in a sea of electrons" to describe metallic bonding.

39. Metallic Bonding Electron Sea Model
Explained by the Electron Sea Model
the atoms in a metallic solid contribute their valence electrons to form a “sea” of electrons that surrounds metallic cations.
delocalized electrons are not held by any specific atom and can move easily throughout the solid.
A metallic bond is the attraction between these electrons and the metallic cation.

40. Metallic Bonding the Electron Sea Model
The more delocalized electrons the stronger the bond