Post on 13-Jan-2016
transcript
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