Which of the following species contain an inversion center? Choose all that apply.
SeF6
[IF4]-
SnF4
InH3
SF6 for sure.
http://en.wikipedia.org/wiki/Point_reflection#Inversion_with_respect_to_the_origin
The answer
To determine which of the following species contain an inversion center, we need to understand what an inversion center is.
An inversion center is a symmetry element in a molecule or an ion that is located at the center and transforms the molecule or ion into itself. It essentially means that if you draw a line passing through the center of the molecule or ion, all atoms on one side of the line must be identical to their counterparts on the other side, but in an inverted orientation.
To identify if a molecule or ion has an inversion center, we can use the following criteria:
1. The molecule or ion must have a center of symmetry, which is a point located at the center.
2. All atoms surrounding the center of symmetry must have an identical atom or group of atoms directly opposite them, but in an inverted orientation.
Now, let's analyze each of the given species to determine if they contain an inversion center:
1. SeF6 (selenium hexafluoride):
- To check for the center of symmetry, we need to identify a point halfway between identical atoms.
- SeF6 has six identical fluorine (F) atoms surrounding the central selenium (Se) atom.
- However, if we draw a line through the center of SeF6, the fluorine atoms on one side do not match the fluorine atoms on the other side.
- Therefore, SeF6 does not have an inversion center.
2. [IF4]- (tetrafluoroiodate ion):
- The bracket "[ ]" indicates an ion.
- To check for the center of symmetry, we need to identify a point halfway between identical atoms or groups of atoms.
- The tetrafluoroiodate ion has four identical fluorine (F) atoms surrounding the central iodine (I) atom.
- If we draw a line through the center of the ion, the fluorine atoms on one side match the fluorine atoms on the other side but in an inverted orientation.
- Therefore, [IF4]- has an inversion center.
3. SnF4 (tin tetrafluoride):
- To check for the center of symmetry, we need to identify a point halfway between identical atoms.
- SnF4 has four identical fluorine (F) atoms surrounding the central tin (Sn) atom.
- If we draw a line through the center of SnF4, the fluorine atoms on one side match the fluorine atoms on the other side but in an inverted orientation.
- Therefore, SnF4 has an inversion center.
4. InH3 (indium trihydride):
- To check for the center of symmetry, we need to identify a point halfway between identical atoms.
- InH3 has three identical hydrogen (H) atoms surrounding the central indium (In) atom.
- If we draw a line through the center of InH3, the hydrogen atoms on one side do not match the hydrogen atoms on the other side.
- Therefore, InH3 does not have an inversion center.
Based on the analysis above, the species that contain an inversion center are:
- [IF4]- (tetrafluoroiodate ion)
- SnF4 (tin tetrafluoride)