Choose the shape (1 to 6) that matches each of the following desc...

Question

Choose the shape (1 to 6) that matches each of the following descriptions (a to c):

1. linear
2. bent (109°)
3. trigonal planar
4. bent (120°)
5. trigonal pyramidal
6. tetrahedral

b. a molecule with a central atom that has four electron groups and three bonded atoms

Accepted Answer

Welcome back, everyone. We need to determine the shape of the molecule that is described below the central atom of a molecule has four electron groups and two bonded atoms. Choice A states that the shape is bent with bond angles of one oh nine degrees. Choice B states that the shape is bent with bond angles of 120 degrees. Choice C states that the shape is trigonal pyramidal and choice D states that the shape is tetrahedral. We're going to begin by recalling that in order to determine our shape of our molecule, we're going to need to find its molecular geometry. Let's recall that molecular geometry is based on the number of bonding groups to our central atom as well as number of lone pairs on our central atom in our structure. Now, molecular geometry differs from electron geometry which is solely based on total electron groups, which consist of our bonding groups plus lone pairs together. So now we're going to refer to our prompt, which states that we have a central atom, which we do not know this identity of our atoms. So we'll say that our central atom is X And we're told that we have four electron groups total and two bonded atoms. So we'll say our two bonded atoms are Y. So we'll place our central atom X in the center and we'll surround it by our two atoms of Y. Now, we're going to begin by making these two atoms of Y bonded to our central atom of X. So we have two bonds between X and Y. Now, this only takes care of two of our electron groups. So far, since we've only drawn in two bonded atoms to fulfill the rest of our two remaining electron groups, we're going to assume that we would have two lone pairs on our central atom. X. So drawing those in, we have two lon pairs on each of the three sides of X in our structure of our molecule. And so thus, we would have two lone pairs plus two bonded atoms Which equal our four electron groups in total. And because we have these four electron groups total, we would be able to interpret that our electron geometry is thus tetrahedral. Now, this doesn't tell us the shape of our molecule. We need to determine our molecular geometry to find that as we stated earlier. So for our molecular geometry, we consider that we have two bonded why Adams to our central atom X? So two bonding groups, and we would also consider that we have two lone pairs on our central atom X. And so therefore, our molecular geometry based on these two lone pairs affecting the way our atoms Y are bonded in our structure will influence the shape of our molecule to be therefore bent with bond angles. We recall from our textbook equal to 109.5 degrees. So going to our answer choices, we would be able to rule out choice B because it gives a bent shape with bond ankles of 120 degrees, which is too high. And we can rule out choices C and D where C says the shape is trigonal pyramidal. And D says this shape is tetrahedral. We saw that tetrahedral corresponded to the electron geometry of our molecule but not its molecular geometry. And so this leaves us with choice a as our only correct choice which states that the shape is bent with bond angles of 109°. So a is our final answer. I hope that this made sense and let us know if you have any questions.

Choose the shape (1 to 6) that matches each of the following descriptions (a to c): 1. linear 2. bent (109°) 3. trigonal planar 4. bent (120°) 5. trigonal pyramidal 6. tetrahedral b. a molecule with a central atom that has four electron groups and three bonded atoms

주요 개념

VSEPR Theory

Electron Groups

Molecular Geometry

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