VSEPR theory is used to predict the shape of a representative molecule for a given covalent chemical compound. Specifically, the shape is based on the arrangement of two or more terminal atoms bonded to the same central atom. The central atom may not necessarily use all of its starting available valence electrons during this bonding, such that non-bonding pairs will remain that influence the shape. VSEPR theory states that the central atom will bond to the terminal atoms by forming a set of hybrid orbitals, which are constructed from some number of its available starting valence atomic orbitals. The hybridization can be derived from the number of covalently-linked terminal atoms and non-bonding pairs on the central atom.
expansion:
Selenium tetrachloride is a covalent compound and its molecule contains a central selenium atom. Based on the main group positions of the elements, the starting numbers of valence electrons are:
Selenium: 6Chlorine: 7 each
Selenium shares 4 valence electrons through 4 single covalent bonds to 4 terminal chlorine atoms. Each chlorine atom shares one valence electron. The numbers of non-bonding pairs remaining are:
Selenium: 1Chlorine: 3 each
VSEPR theory states that a central atom with 4 covalently-linked terminal atoms and 1 non-bonding pair adopts a see-saw molecular geometry. Based on these details, the central selenium will have an orbital hybridization of:
sp3d" role="presentation" style="display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.66px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">sp3dsp3d
