Chapter 6- Shapes of Molecules and Intermolecular forces Flashcards
What does a dotted wedge mean when drawing displayed formulae of compounds?
A bond going into the plane of the paper
What does a solid wedge mean when drawing displayed formulae of compounds?
A bond coming out of the plane of the paper
Why does a lone pair repel more that bonded pairs?
Slightly closer to the central atom, and occupies more space than a bonded pair.
What is the name and bond angle for a molecule with 4 bonded pairs and no lone pairs?
Tetrahedral, 109.5
What is the name and bond angle for a molecule with 3 bonded pairs and 1 lone pairs?
Trigonal pyramidal, 107
What is the name and bond angle for a molecule with 2 bonded pairs and 2 lone pairs?
Non- linear, 104.5
What is the name and bond angle for a molecule with 2 bonded pairs and no lone pairs?
Linear, 180
How many bonded pairs does a double covalent bond count as?
1
What is the name and bond angle for a molecule with 3 bonded pairs and no lone pairs?
Trigonal planar, 120
What is the name and bond angle for a molecule with 6 bonded pairs and no lone pairs?
Octahedral, 90
Define Electronegativity
The attraction of a bonded atom for the pair of electrons in a covalent bond
How is electronegativity measured?
Using the Pauling scale
When will a molecule be non-polar?
The bonded atoms are the same OR the bonded atoms have the same or similar electronegativity values
What is the separation of opposite charges known as?
A dipole
Does Carbon dioxide have a dipole?
No, as the molecule is symmetrical
Describe London Forces (Induced dipole-dipole interactions.)
Weak intermolecular forces that exist between all molecules, polar or non-polar .
What are permanent dipole-permanent dipole interactions?
Intermolecular force between the slightly positive end of on molecule and the slightly negative side of another molecule
Which is stronger, London forces, or permanent dipole-permanent dipole interactions?
Permanent dipole-permanent dipole interactions
What kind of bonding is present in HCl?
Permanent dipole-permanent dipole interactions and London forces
What kind of bonding is present in Carbon dioxide?
London forces only
What is Hydrogen bonding?
A special type of permanent dipole-permanent dipole interaction found between a Hydrogen with a Oxygen, Nitrogen or Fluorine
Which intermolecular force is strongest?
Hydrogen bonding
Why is ice less dense than water?
Hydrogen bonding holds water molecules apart in poen lattice structure
The water molecules in ice are further apart than in water
This makes ice less dense and so floats in water.
Why does water have a relatively high melting point and boiling point?
Each water molecule makes 4 Hydrogen bonds which require a lot of energy to break so water has a higher boiling point and melting point than expected.
