4. Polarity (Structure) Flashcards
why is important to know the arrangement of molecules with 3 or more atoms?
In order to deal with the polarity of the atoms.
How is the geometry of the atoms understood? (2)
-by considering valence shell electron pair repulsion theory (VSEPR). -arranging the bonding electron pairs and lone electron pairs in the outer level of electrons so that they are positioned as far away from each other as possible.
True or false, electron pairs will arrange themselves as far as possible from one another.
True. In order to avoid electron-pair repulsion.
Why do ‘lone pairs’ repel negative charge more effectively than ‘bonding pairs’?
As they can be perceived to require more space around the central atom (existing in a cloud rather than linearly along the bond).
What happens as the number of lone pairs increase?
The bond angle decreases.
What needs to be determined in order to see of a molecule is polar or non-polar? (2)
-The electronegativity. -The structure/bonds. Note that if the bond is polar, the molecule is polar.
What is the angle of a linear shaped molecule?
180º.
What is the angle of a linear shaped molecule, with three atoms?
180º.
What is the angle of a ‘trigonal planar’ shaped molecule?
120º.
What is the angle of a ‘tetrahedral’ shaped molecule.
109º.
What is the angle of a ‘trigonal pyramidal’ shaped molecule’?
107º.
What is the angle of an ‘angular/bent’ shaped molecule?
105º.
Which shapes contain atleast one lone pair of elections? (2)
- Trigonal pyramidal
- Angular/bent
What must a molecule be if it is a polar molecule?
It must be a dipole.
What are molecules called when their charge distribution is permanently uneven?
They are said to possess a dipole moment or are said to be polar molecules. Occuring when the molecule is asymmetrically arranged. (One has a permanent but very samll negative charge and the other end has a permanent but very small postive charge).
