Unit 7 Flashcards
bHow to draw Lewis Dot Structures?
- Identify the central atom (aka the atom we have one of).
- If there is more than one, they will be next to eachother.
- Draw the central atom in the center and the other atoms around it.
- Add the valence electrons and bond to satisfy octet rule.
Which atom(s) only need 2 valence electrons to be stable?
Hydrogen and Helium.
Which atom(s) only need 6 valence electrons to be stable?
Aluminum and Boron.
What does charges mean in the formula?
Signifies the amount of electrons gained or removed. Negative is gained and positive is removed.
How must you draw the electrons?
Don’t leave two electrons separate, combine them.
VSEPR Linear structure
Central atom is bonded twice with NO lone pairs. 180 degrees
VSEPR Trigonal planar
Central atom is bonded three times with NO lone pairs. 120 degrees.
VSEPR Tetrahedral
Central atom is bonded four times with NO lone pairs. 109.5 degrees bond angle
VSEPR Bent
ONE lone pair = 120 degrees
TWO lone pairs = 109.5 degrees
VSEPR Trigonal pyramidal
Central atom is bonded three times with ONE lone pair. 109.5 degrees.
The three different types of bonds
Ionic
Polar covalent
Nonpolar covalent
Polar covalent bonds
CAN contain a dipole.
Difference in electronegativity of the atoms is greater than 0.5 but less than 1.67.
Nonpolar covalent bonds
Difference in electronegativity of the atoms is less than 0.5.
Ionic bonds
Difference in electronegativity of the atoms is greater than 2.0.
What symbol goes over the molecule with greater electronegativity?
-
What symbol goes over the molecule with less electronegativity?
+
Dipole
Caused by a difference in electronegativity where one part of the molecule becomes slightly negative and the other becomes slightly positive.
Intramolecular forces
The two main categories of bonds that occur within a molecule. Covalent (Polar and nonpolar) and ionic bonds.
Intermolecular forces
Affect the boiling point. The higher the IMF, the higher the boiling point. They determine whether a molecule will dissolve in a particular solvent. Polar molecules dissolve in polar solvents.
Types of IMF
Dipole-Dipole. Strong
Hydrogen bonding (a type of dipole-dipole) Strongest
London Dispersion Forces (LDF) Weakest
Dipole-Dipole
ONLY polar covalent molecules withe a dipole.
Molecules with a dipole can be attracted to other molecules with dipoles.
- 2nd strongest IMF
Hydrogen bonding
ONLY polar covalent molecules withe a dipole.
This time molecules that bond hydrogen with F.O.N. (Fluorine, oxygen, nitrogen)
- Strongest IMF
London Dispersion Forces (LDF)
Between molecules with NO DIPOLE and always (but no exclusively) nonpolar covalent molecules and sometimes polar covalent.
There are some attraction to other molecules, known as temporary dipoles.
- Higher mass, stronger dipole
- Weakest IMF
