VSEPR Theory Flashcards
What is an electron group?
A set of electrons that occupies a particular region around an atom. Examples: lone pairs, bonds
What term describes how the ligands of a molecule, as opposed to the electron groups, are arranged in a molecule?
Molecular shape
What are the possible molecular shapes of a molecule with tetrahedral electron group geometry?
Tetrahedral, trigonal pyramidal, and bent.
How is the steric number determined?
Number of ligands + number of lone pairs
Describe the four steps to determining molecular shape.
Lewis structure
Steric number
Electron group geometry
Ligand count
What is electron group geometry?
The three-dimensional arrangement of valence shell electron groups.
What is the ideal bond angle for a molecule with linear shape and geometry?
180*
What is the steric number and ideal bond angle for a molecule with trigonal planar shape and electron group geometry?
3; 120*
What is the electron group geometry of a molecule with steric number 5?
Trigonal bipyramidal
Give the ideal bond angle(s) of a molecule that has trigonal bipyramidal electron group geometry.
120* between equatorial positions; 90* between axial positions.
A molecule has 5 electron groups, and one of them is a lone pair. Give the two possible molecular shapes.
Trigonal pyramid
Seesaw
A molecule with octahedral electron geometry can have up to two lone pairs. Give the three possible molecular shapes.
Octahedral
Square pyramidal
Square planar
The bond angles of a molecule are all 109.5*. Give the electron group geometry.
Tetrahedral
True or false: lone pairs repel other electron groups less strongly than those groups repel each other.
Why?
False. Electrons in a lone pair are more strongly attracted to their nucleus than bonding electrons.
What are the key factors in determining the dipole moment of a molecule?
Electronegativity differences and molecular geometry.
