molecular compounds - ms. goldenberg
TRANSCRIPT
Molecular Compounds
Molecular Compounds
Molecule: Combination of two or more atoms held together by covalent bonds
Covalent bonds:When two non-metal atoms share electrons
Diatomic Molecules
Diatomic molecule: When two atoms of the same elements are joined by covalent bonds (Cl2, Br2, HF)
Molecular Compounds
Molecular Compound: When two or more different non-metals come together and share electrons to form covalent bonds.
In each bond, the atoms share a single pair of electrons.
Molecular Compounds
For example, water is a molecular compound with two covalent bonds
Each hydrogen atom shares one pair of electrons with an oxygen atom
Properties of Molecular Compounds
soft low melting point solutions do not
conduct electricity
Naming Molecular Compounds
1.Name the first element2.Name the second element and change the ending to “-ide”3.Add prefixes to indicate the number of each atom
Naming Molecular Compounds
Example 1: N2O
Naming Molecular Compounds
The prefix “mono” is not used when there is only one atom of the first element
When two vowels are next to each other, drop the vowel in the prefix
e.g. “monoxide” not “monooxide”e.g. “pentoxide” not “pentaoxide”
Naming Molecular Compounds
Example 2: PBr3
Naming Molecular CompoundsName the following molecular
compounds: PCl3
AS3P5
diphosphorous pentoxide
carbon disulfide
Naming Molecular Compounds
Many compounds containing hydrogen have been given simpler names
For example, dihydrogen monoxide (H2O) is simply called “water”
Naming Molecular Compounds
Molecular Compound Diagrams
Lewis Dot Diagram
Structural Diagram
Line Diagram (MaCS)
Lewis Dot Diagram only valence electrons are shown only UNPAIRED ELECTRONS can be shared Arrangements of electrons around the element
name must take on the same orientation as if there was an imaginary orbital ring around the atoms
WRONG WAY RIGHT WAY
H . . H H H : H H: . .
H H
Lewis Dot Diagram
Draw Lewis dot diagrams for the following examples on your worksheet: H2O CO2 NH3 CH4
Drawing Molecular CompoundsLewis diagrams can be quite time
consuming and is difficult to read and thus most textbooks use alternate forms of representation: Structural diagrams Line diagrams
Structural Diagram Each pair of shared electrons is replaced
with a single line segment connecting the two atoms
Each single line represents a bond If two atoms share 4 electrons (2 pairs), then
you would use 2 line segments (like an equal sign) representing double bonds
Lone pairs of electrons (electron pairs that are not shared) are NOT shown
Lewis Dot Diagram
Draw Lewis dot diagrams Structural diagrams for the following examples on your worksheet: H2O CO2 NH3 CH4
Structural Diagram
Practice: translate this Lewis Dot diagram into a structural diagram
SummaryAtom # of valence
electrons# of unpaired electrons (can be shared)
# of bonds
H
O
N
C
SummaryAtom # of valence
electrons# of unpaired electrons (can be shared)
# of bonds
H 1 1 1
O 6 2 2
N 5 3 3
C 4 4 4
Molecular Compound Diagrams
Lewis Dot Diagram
Structural Diagram
Line Diagram (MaCS)