If you like us, please share us on social media.
The latest UCD Hyperlibrary newsletter is now complete, check it out.

GeoWiki.png
ChemWiki: The Dynamic Chemistry E-textbook > Inorganic Chemistry > Molecular Geometry > Trigonal Planar Molecular Geometry

MindTouch
Copyright (c) 2006-2014 MindTouch Inc.
http://mindtouch.com

This file and accompanying files are licensed under the MindTouch Master Subscription Agreement (MSA).

At any time, you shall not, directly or indirectly: (i) sublicense, resell, rent, lease, distribute, market, commercialize or otherwise transfer rights or usage to: (a) the Software, (b) any modified version or derivative work of the Software created by you or for you, or (c) MindTouch Open Source (which includes all non-supported versions of MindTouch-developed software), for any purpose including timesharing or service bureau purposes; (ii) remove or alter any copyright, trademark or proprietary notice in the Software; (iii) transfer, use or export the Software in violation of any applicable laws or regulations of any government or governmental agency; (iv) use or run on any of your hardware, or have deployed for use, any production version of MindTouch Open Source; (v) use any of the Support Services, Error corrections, Updates or Upgrades, for the MindTouch Open Source software or for any Server for which Support Services are not then purchased as provided hereunder; or (vi) reverse engineer, decompile or modify any encrypted or encoded portion of the Software.

A complete copy of the MSA is available at http://www.mindtouch.com/msa

Trigonal Planar Molecular Geometry

AX3 AX3
Shape: trigonal planar
  Steric Number: 3
  Lone Pairs: 0
  Polar/NonPolar: NonPolar
  Hybridization: sp2
  Examples: BF3, CO32-

NOTES: This molecule is made up of 3 equally spaced sp2 hybrid orbitals arranged at 120o angles. The shape of the orbitals is planar triangular. Since there is an atom at the end of each orbital, the shape of the molecule is also planar triangular.

Boron Hydride

An example of trigonal planar electron pair geometry and molecular geometry is BH3. This molecule is electron deficient and does not follow the octet rule because it has only 6 valence electrons. The hydrogen atoms are as far apart as possible at 120o. This is trigonal planar geometry. The molecule all in a plane and is two dimensional.This molecule exists in a gaseous state in only minute quantities under specialized conditions as an intermediate in the making of other boron hydride type molecules.

203bh3.gif

Formaldehyde

In this example, H2CO, the Lewis diagram shows carbon at the center with no lone electron pairs. The carbon and and the oxygen are bonded through a double bond which counts as "one electron pair". Hence the molecule has three electron pairs and is trigonal planar. Formaldehyde is the simplest member of a class of organic compounds called aldehydes. These compounds have the structural component of the carbon double bond oxygen and at least one hydrogen atom and are always in the trigonal planar format geometry.

Formaldehyde or methanal is a water soluble gas. A 37% solution is water, known as formalin, is a biological preservative and in used in embalming fluids.

203formaldehyde.gif

Carbonate Ion

In this example, CO32-, the Lewis diagram shows carbon at the center with no lone electron pairs.

The Lewis diagram is as follows:
C = 4 e-
O = 6e- x 3 = 18e-
2- charge = 2e-
Total electrons = 24

One double bond is needed to give carbon an octet. The carbon and oxygen are bonded through a double bond which counts as "one electron pair" and two single bonded oxygens. Hence the molecule has three electron pairs and is trigonal planar geometry. Carbonate ion is present in limestone as calcium carbonate. A form of it, bicarbonate, is in baking soda and baking powder.

203co3-2.gif

Contributors

You must to post a comment.
Last Modified
12:41, 6 Nov 2014

Tags

Classifications

(not set)
(not set)

Creative Commons License Unless otherwise noted, content in the UC Davis ChemWiki is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. Permissions beyond the scope of this license may be available at copyright@ucdavis.edu. Questions and concerns can be directed toward Prof. Delmar Larsen (dlarsen@ucdavis.edu), Founder and Director. Terms of Use