1. Molecular Compounds

2. Molecular Compounds
Molecular compounds are formed when atoms of two or more different elements share electrons. Usually formed between 2 or more non-metals and are also called covalent compound. A covalent bond is formed when electrons are shared between atoms. For example, water (H2O)

3. Ionic vs. Molecular Ionic Compounds Molecular Compounds
How atoms bond?
Transfer of electron(s)
Share of electrons
What bonds with what?
Metal to non-metals
Non-metal to non-metal
What do they form?
Lattice structure (solids)
Solid, liquid or gas

4. Diatomic Gases
Elements that have two atoms joined by one or more covalent bonds to form a molecule The anagram is HOBrFINCl H2 O2 Br2 F2 I2 N2 Cl2

5. Draw Lewis Diagram
H2 Br2 F2 I2 N2 Cl2

6. What is the difference between a molecular formula and structural formula?
A molecular formula is a chemical formula – it shows the number of atoms of each element. A structural formula shows the arrangement of the atoms that make up a molecule.

7. Binary Molecular Compounds
Binary molecular compounds are compounds composed of two non-metals joined by one or more covalent bonds.

8. Naming Binary Molecular Compounds
Use a prefix to indicate the number of each atom present.
Molecular Compounds Prefixes
1 Mono Hexa-
2 Di Hepta-
3 Tri Octa-
4 Tetra Nona-
5 Penta Deca-
Example: Carbon dioxide tells us it is made of 1 carbon atom and 2 oxygen atoms
Note: don’t use mono for the first non-metal in the chemical formula

9. Naming Binary Molecular Compounds
Count the # of atoms of the first element.
Write the prefix for this number followed by the name of the first element. If there is only one of the first element we leave out the prefix.
Count the # of atoms of the second element.
Write the prefix for this number followed by the name of the element using the suffix –ide
Example:
N2O4
Nitrogen atoms = 2  dinitrogen
Oxygen atoms = 4  tetraoxide = tetroxide
Full name = dinitrogen tetroxide
Example:
C2F6
Carbon atoms = 2  dicarbon
Fluorine atoms = 6  hexafluoride
Full name = dicarbon hexafluoride

10. Writing Chemical Formulas for Binary Molecular Compounds
Write the symbol for the elements.
Write the subscript for the number of atoms represented by the prefix.
Notice – the ratio in the formula is not reduced to its simplest form like ionic compounds.
Example:
Sulfur trioxide SO3
Diphosphorus pentasulfide P2S5