3: Bonding and Intermolecular Forces Flashcards
(34 cards)
What is electron pair repulsion theory?
Electrons are all negatively charged so they repel each other and try to be as far apart as possible.
Name the shape of a molecule with 2 bonding pairs.
Give the bond angle.
Linear
180
Name the shape of a molecule with 3 bonding pairs.
Give the bond angle.
Trigonal planar.
120
Name the shape of a molecule with 4 bonding pairs.
Give the bond angle.
Tetrahedral
109.5
Name the shape of a molecule with 3 bonding pairs and 1 lone pair.
Give the bond angle.
Trigonal pyramidal
107
Name the shape of a molecule with 2 bonding pairs and 2 lone pairs.
Give the bond angle.
Bent
104.5
Name the shape of a molecule with 5 bonding pairs.
Give the bond angles.
Trigonal bipyramidal.
90 and 120
Name the shape of a molecule with 4 bonding pairs and 1 lone pair.
Give the bond angles.
See saw
86.5
102
Name the shape of a molecule with 3 bonding pairs and 2 lone pairs.
Give the bond angle.
T shape.
87.5
Name the shape of a molecule with 6 bonding pairs.
Give the bond angle.
Octahedral
90
Name the shape of a molecule with 5 bonding pairs and 1 lone pair.
Give the bond angle.
Square pyramidal
90
Name the shape of a molecule with 4 bonding pairs and 2 lone pairs.
Give the bond angle.
Square planar.
90
Give the shape of CO2.
Linear
180
Give the shape of SO2.
Bent
120
What is a dipole?
An uneven distribution of charge caused by a shift in electron density in a bond.
Define electronegativity.
The ability of an atom to draw electrons towards itself within a covalent bond.
Describe how van der waals forces form.
At any moment, electrons can be distributed on either side of a molecule. This means one side is more positive or more negative (temporary dipole). This induces a temporary dipole in another neighbouring atom. This continues throughout a set of molecules because they are always moving, meaning that dipoles are constantly being created and destroyed. This means there is constant attraction throughout.
Describe molecules that form stronger van der waals forces.
Larger molecules, because they have larger electron clouds.
Describe the shape of molecules that allow for stronger van der waals forces.
Straight, unbranched, linear molecules because they can pack closer together and form stronger forces.
Why do molecules with stronger van der waals forces have higher boiling points?
More energy is required to overcome the boiling point.
What are permanent dipole-dipole forces?
IMFs that occur between molecules with a permanent dipole. The slightly negative side of a molecule with a dipole attracts to the slightly positive side of a neighbouring molecule.
Hydrogen bonds can only be formed between hydrogen and what 3 other atoms?
Why?
N, O, F
These atoms are very electronegative so draw the electrons away from the hydrogen atoms.
Describe how hydrogen bonds are formed.
A dipole is formed between hydrogen and N, O, F. This means the hydrogen is slightly positive and slightly negative. In neighbouring molecules, the slightly positive hydrogen attracts to the lone pairs on the electronegative atom.
What happens when liquids with hydrogen bonds cool and become solid?
They arrange themselves into a regular lattice structure.
