Chemistry: Chapter 8- COVALENT BONDING
Properties of a molecular compound
- lower melting and boiling points than ionic compounds - weaker attraction than ionic bonds - exist as individual molecules
Mono
1
Steps for drawing lewis structures
1. Determine the total number of valence electrons in the compound 2. Determine the needed number for stability 8 or 2 3. Step 1 -step 2 then divide by 2 4. Step 1- step 3
Deca
10
Di
2
Tri
3
Tetra
4
Penta
5
Hexa
6
Hepta
7
Octa
8
Nona
9
Sigma bond
A bond formed when two atomic orbitals combine to form a molecular orbital that is symmetric around the axis connecting the two nuclei
Covalent bond
A chemical bond that results when atoms share valence electrons
What are molecular compounds represented with?
A chemical formula that shows the kinds and numbers of atoms present in a molecule of the compound
Molecular formula
A chemical formula that shows the kinds of numbers of atoms present in a molecule of the compound
Binary molecular compound
A compound that involves two Nonmetals sharing electrons
Molecular compound
A compound that is composed of molecules
Coordinate covalent bond
A covalent bond in which one atom contributes both bonding electrons
Pi bond
A covalent bond in which the bonding are most likely found in sausage- shaped regions above and below the bond axis of the bounded electrons
Non- polar covalent bond
A covalent bond in which the bonding electrons are shared equally between the two atoms
What is another name for a molecular compound?
A covalent compound
VSEPR model
A model used to determine the shape of a molecule
Bonding orbital
A molecular orbital that can be occupied by two electrons of a covalent bond
Diatomic molecule
A molecule that contains two atoms typically of the same element
Molecule
A neutral group of atoms joined together by covalent bonds
What do covalent bonds allows the atoms in the bond to have?
A stable octet
Polyatomic ion
A tightly bound group of atoms that behaves as a unit and has a positive or negative charge
When do covalent bonds form?
Between two Nonmetals
Ionic bond
Bond formed from the attraction of oppositely charged ions
Polar covalent bond
Covalent bond in which the bonded atoms have an unequal attraction for the shared electrons
Which elements are found in nature as diatomic?
Hydrogen, oxygen, nitrogen, and halogens
Resonance structure
One or more of the equally valid leiws structures of a molecule or polyatomic ion
Molecular orbital
Orbitals that apply to the entire molecule
How do you name a binary molecular compound?
Place a prefix on each element's name to show how many of that atom is present Drop the ending of the second element's name and replace with ide
What is the difference for a lewis structure for a polyatomic ion
Place the lewis structure in brackets with the charge outside
How does the lewis structure of a polyatomic ion differ from that of a single ion?
Put the structure in brackets with the charge outside
4 e clouds (2 bonds and 2 unshared)
Shape: bent Bond angle: 105
2e clouds
Shape: linear Bond angle: 180
4e cloud(4 bonded atoms)
Shape: tetrahedral Bond angle: 109.5
3e clouds
Shape: trigonal planar Bond angle: 120
4e cloud (3 bonds & 1 unshared )
Shape: trigonal pyramidal Bond angle: 107
Electronegativity
The ability of an atom to attract electrons to itself when it is chemically bonded
Writing formulas from names
The prefix tells you the number so that number becomes the subscript
Single bonds
The sharing of one pair of electrons between two atoms
T or F: Hydrogen and the halogens are NOT usually bonded to only 1 other atom
The sharing of three pairs of electrons between two atoms
Triple bonds
The sharing of three pairs of electrons between two atoms
T or F: the atom with the lowest electronegativity is usually in the center
True
T or f: if only one of the first element is present, no prefix is used
True
True or false: single bonds are always sigma bonds
True
What does it stand for?
Valence Shell Electron Pair Repulsion
When would you have a resonance structure ?
When multiple bonds are involved
how are molecular compounds different from ionic compounds
a molecular compound is formed by a covalent bond, which involves a sharing of valence electrons. an ionic compound is formed by an ionic bond, which involves either going or losing electrons.
how to draw lewis structures
determine the total number of valence electrons in the compound, determine how many electrons are needed to be stable, determine the number of shared electrons (step 1- step 2) and divide shared by two, subtract shared from valence electrons
lewis structure
diagram that shows the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule
rules for electronegativity
increases as you move upwards in a group (vertical), increase from left to right across a period
how does the VSEPR theory help to predict the shape and bond angle of molecules
scientists use the vesper model to explain the 3d shape of molecules. the theory states that the repulsion between electron pairs causes molecular shapes to adjust so that the valence electron pairs stay as far apart as possible. to determine the shape you count the number of electron clouds surrounding the central atom and predict shape bed on number of clouds
Double bonds
the sharing of two pairs of electrons between two atoms
