Bonding

Chemical StabilityKnowing this information about

oxidation numbers, which elements are the most chemically stable elements?

Noble gases- Are the most stable elements- They have 8 valence electrons and don’t want to gain or lose any electrons

Chemical BondsOnly involve ELECTRONS

The nucleus does not matter here

Elements will not just lose or gain electrons. They will give to another element or take from another element

There will always be AT LEAST 2 atoms involved in this process.Binary Compound = Compound with ONLY

2 elements in itNaCl, CaCl2, K2S, etc..

Properties of BondsRemember that when atoms bond, they form new

compounds with different properties.The final product has different properties than

either of the initial single elements

Types of Chemical BondsThere are 3 different ways that two

(or more) atoms can interact or BOND3 types of bonds:

Ionic CovalentMetallic

Ionic BondsFormed when one atom gains an electron and another atom loses an electrons. One atom transfers their electrons to the other atom.

Ionic Bonds

More on Ionic BondsOccurs between a metal and a nonmetal.Two oppositely

charged ions.

The product is a neutral compound – and the oxidation #’s add to zero!If they don’t add to

zero, you did it wrong.

Properties of Ionic CompoundsStronger bondsHigh melting pointsConduct electricity when in solution

or in a molten stateGenerally dissolve in water

Generally crystalline solid at room temp.

Drawing Ionic BondsLets use NaCl (a metal and a nonmetal)

1st – Determine the oxidation numbersNa = 1+ Cl = 1-

2nd – Draw the Lewis Structure for each atom

3rd – Draw the electron(s) being transferred in the proper direction

DOUBLE CHECK:Does each atom have a full valence orbital?

Practice Drawing Ionic BondsK and Br

Mg and Cl

K and S

Types of Chemical BondsThere are 3 different ways that two

(or more) atoms can interact or BOND3 types of bonds:

Ionic CovalentMetallic

Covalent BondsOccur between two nonmetals. Formed when two atoms share electrons with one another.

Can be between two different atoms, or between two atoms of the same elementAlso called Molecular compounds

aka MOLECULE

Properties of Covalent BondsWeaker bondsLow melting and boiling pointsDo NOT conduct electricity when in solutionGenerally don’t dissolve in water.

Many are gases or liquids at room temperature

Drawing Covalent BondsLets use HCl (2 non-metals)

1st – Draw the Lewis Structure for each atom

2nd – Draw the electron(s) being shared

3rd – Draw each covalent bond as a line between the two atoms

DOUBLE CHECK:Does each atom have a full valence orbital?

PRACTICE COVALENT BONDSHCl

H20

CH4

Diatomic Molecules Two atoms of the same element covalently bonded together. They cannot exist as lone atoms and must bond to something.

Called Molecules

I Br Cl F O N H BrINClHOFSeven form a seven

How do you know which type of bond is formed?

IONIC COVALENT

- Metal and Nonmetal - Two Non Metals

- Transfer Electrons - Share Electrons

Bond Types (cont’d)Metallic—Between two metals

All metals want to give away electrons because they have + oxidation numbers

Don’t transfer electrons specificallyAllow electrons to flow from one atom to another. Can pass between many atoms.