Compounds

Which Elements form Ionic Bonds?

• The central idea (for the 51st time) is that electrons, one or more, are transferred between the outer shells of adjacent atoms. This creates Ions/Charged Atoms.

• Metals and NonMetals.

• Cation and anion.

• Certain Elements may donate or receive more than one electron. It can therefore bond with multiple elements, with different ratios

REVIEW

History

• Before 1913, all bonds were considered to be of the Ionic Type (called polar at the time).

• When doing Ion Beam analysis for CO it was found that the beam was evenly split between Carbon and Oxygen.

• Early work was done by Thompson and Rutherford.

Covalent Bonds

• The sharing of electrons in order to achieve a more STABLE electron structure.

• Atoms are held together closely by the strong bond.

• Atoms that have similar electronegativity values hold onto their electrons with the same amount of force. They therefore do not readily donate electrons.

Molecules

• The smallest amount of a covalent compound that still has the properties of that compound.

• The result of atoms held together by covalent bonds.

• CO2

• SO4

Different Types of Covalent Bond

• Single Bond– Two electrons shared between two atoms.

• Double Bond– Four electrons shared between two atoms.

• Triple Bond– Six shared electrons between two atoms.

Single Bonds

• Example: Halogens– F2, Cl2, Br2, etc.

• Take place when 2 electrons are shared between 2 atoms.– Two atoms of the same element bonded to

Itself.

Double Bonds

• Four Electrons shared between two atoms.

• Example: The Chalcogens

Triple Bonds

• Six electrons share between two atoms.

• Nitrogen is involved in many molecules with a triple bond.

Covalent Bond Diagrams

Nitrogen

Hydrogen

Covalent Bond Diagrams

N N

H

HH

H

NH3

Diagram

e-e-

H N H

H

Practice Exercise #1

• Diagram the following Molecules and list what type of bond they have:

– F2 - CO2

– Cl2 - H20

– O2 - N2

– SO - NO

Naming Covalent Compounds

Naming Simple (Binary)

Covalent Compounds

Prefixes

1 mono- 6 hexa-

2 di- 7 hepta-

3 tri- 8 octa-

4 tetra- 9 nona-

5 penta- 10 deca-

Rules for namingCovalent Compounds

• Name the 1st element by keeping its elemental name.Use a prefix only when there is more than one of that element.

• Name the 2nd element as if it were a negative ion. (ide)Always use a prefix.

Watch awkward pronunciations

Tetraoxide or Tetroxide

Carbon Mono-oxide or Carbon Monoxide

Write the following formulas

nitrogen dioxidetetraphosphorus

heptasulfide

carbon tetrachloride tribromine octaoxide

Name the following compounds

C3O2 BrF3

P2O3 IF6