How to Determine if a Molecule Is Planar

Formaldehyde (H2CO) contains planar molecules.
••• Hemera Technologies/ Images

A molecule's shape depends on the atoms that make it up and the electrons that belong to the central atom. If the atoms arrange themselves around the central molecule so that they exist on a single two-dimensional plane, the molecule is planar. The molecule may otherwise form any of several three-dimensional shapes, including tetrahedrons, octahedrons or bipyramids. A molecule's shape affects its material's physical properties, such as its color and phase of matter, and determines how it reacts with other molecules.

    Count the number of atoms than bond to the molecule's central atom. For example, if you are calculating the shape of sulfur tetrafluoride, note that four fluorine atoms bond to the central sulfur atom.

    Count the number of lone pairs of electrons on the central atom. A sulfur atom contains six valence electrons, and four bond with the fluorine atoms. That leaves a single lone pair of electrons.

    Check whether the the molecule either has three bonded atoms and a single lone pair, in which case it is trigonal planar, or has four bonded atoms and two lone pairs, in which case it is square planar. Sulfur tetrafluoride has neither of these configurations. It is therefore not planar.


    • All molecules with fewer than four atoms are technically planar. Yet chemists do not refer to them as such, instead calling them linear or angled depending on their configuration.

Related Articles

How to Tell if a Molecule Is Bent
How to Determine How Many Dots Are on an Element's...
How to Find Out If an Element Is an Ion
How to Calculate a Steric Number
What Is the Comparison Between Atoms & Molecules?
How to Determine How Many Hybrid Orbitals
How to Calculate Valency of Radicals
How to Find the Number of Ions in a Compound
What Is the Difference Between Electronic Geometry...
What Forms When Two or More Atoms Combine?
Number of Protons in an Uncharged Atom
How Do Polar Molecules Form Hydrogen Bonds?
How to Calculate the Radius of an Atom
How to Find the Number of Unshared Electrons
Definition of Molecular Bonds
How to Figure Out the Chemical Symbol for Ions
Describe the Formation of Both Positive & Negative...
How to Find the Polarity of Compounds
Examples of Elements Without a Stable Electron Configuration
How to Calculate a Fraction Covalent

Dont Go!

We Have More Great Sciencing Articles!