Bonding Flashcards
Chap 3
3 types of bonding in the periodic table
Simple covalent (most)
Giant covalent (C & Si)
Giant metallic (most)
How many ionic metals are involved in metallic bonding?
1
What metal ions don’t form noble gas structures when ionic bonding?
Transition metals
Metals after transition metals
True or false: all negative ions aim to have noble gas structures
True
What determines how many electrons are transferred for cations of transition metals and the metals after transition metals (who are not trying to achieve noble gas structures)?
Ionisation energies
True or false: all non metals covalently bond to create noble gas structures
False— some are validly stable if they make the max no. Of bonds
What holds covalently bonded atoms together? (3 points)
electrostatic attraction between
pos nuclei and
neg shared electron pairs
Coordinate/Dative covalent bond
covalent bond when both shared electrons are provided by 1 atom (and the atom accepting e- must have an incomplete outer shell)
What is the “lone pair” in covalent bonding? How are they used in dative covalent bonding?
Electrons not being used in bonding
Donor atoms will use they lone pair in a dative covalent bond (so other atom doesn’t have to give any)
What makes an ionic bond strong? What do these 2 things lead to?
- small ionic radius (shielding comes under this)
- big ionic charge
greater electrostatic attraction
What makes a covalent bond strong? What is the strongest kind of covalent bond?
The shorter the bond (the more electron pairs are shared) the stronger the bond
Triple bonds
What makes a metallic bond strong? (2 reasons)
Smaller atoms (minor point) and more delocalised electrons
Electronegativity
the measure of strength of attraction for a pair of e-
Electronegativity trends and why:
1) Across a period
2) Down a group
1) increases
- nuclear charge inc
- atomic radius dec
- shielding =
2) decreases
- nuclear charge inc
- atomic radius inc
- shielding inc
Types of bond polarity
Ionic
Polar covalent (diff electronegativity)
Non polar covalent (same electronegativity)
True or false: tetrachloromethane is a polar molecule where the dipoles don’t cancel out
False- they do cancel out as the neg chlorine cancel out the pos carbon in the middle
Bond dipole moment
A measurement of the strength and direction of the polarity in a bond (bigger electronegativity=bigger BDM)
What is VSEPR? What is it used for?
- the theory that e- pairs on the outer shell repel each other
- predict the geometry of a molecule
Do bonding or non bonding pairs cause a bigger repulsion? By how much?
Non bonding pairs
2.5 degrees
Match the number of BONDING pairs to the correct shape:
2
3
4
5
6
Linear
Trigonal planar
Tetrahedral
Trigonal bipyramidal
Octahedral
3 types of IMF (weakest to strongest)
Van der Waals
Permanent dipole-dipole attractions
Hydrogen bonds
Why are the 3 IMF weak/strong?
- Van der waals only induce temporary dipoles due to rapid movement of e-
- whereas dipole-dipole is permanent
- and hydrogen bonds cause a high charge density
What molecules do the 3 IMF occur in?
- Van der waals: ALL
- Permanent d-d: polar MOLECULES only
- Hydrogen bonds: any molecule where H BONDS to N, O or F
What factors, other than IMF, affect boiling points?
- Chain lengths of alkanes (longer=more IMF=higher BP)
- Branched alkanes (more branches=less packing=lower BP)
