It is essential to know the Lewis structure of a molecule to recognize its physics properties, hybridization, and shape of the molecule. Now we are going come go with the Lewis framework of I3- or likewise know as Triodide ion as it has a an adverse charge top top it. There 3 molecules that iodine in this molecule and also hence the name of the compound are Triodide. For expertise the Lewis framework of the molecule, us should understand valence electrons that the iodine molecule.

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Lewis Structure 

Lewis framework is the depiction of the electrons of the molecules. There room lone pairs and also valence electron which help in identify the hybridization and shape of the molecule. As there space molecules the Iodine, one molecule the Iodine will be in the centre. Also, iodine is in the seventh team of the routine table and also has 7 valence electron in its external orbit.


We have actually three molecule of iodine here which together with an extra electron which gives it a an adverse charge. For this reason the total number of valence electrons room : 7×3 + 1= 22.There space 22 valence electrons in complete in this molecule. Now there is an octet preeminence that every atom follows. As per this rule, every atom should have eight electron in their outer orbit. If there are 8 electrons in the external shell that the main atom, there are two other atoms that need to finish their octet. As all the atom will call for eight electron in their outer shell to finish the octet one electron that the central Iodine atom will be bring away by both the adjoining Iodine atoms. That method 8-1-1=6.As the electrons will certainly be taken by both the atoms.

So now the valence electrons on the central atom that iodine will certainly be six. These six electrons will form the lone pairs of electron that perform not bond. As it forms the pair of electrons now, there will certainly be 3 lone pairs, and also two bond bag of the electrons together each Iodine atoms has actually a bond through the central atom share one electron each in complete there 3 lone pairs and 2 bond bag on the central atom.



For discovering the hybridization of any molecule, there is a straightforward formula which deserve to be used. This formula is supplied for finding the end the hybridisation number which helps in learning the hybridisation that the molecule.

The hybrid numbers and the hybridisation it identify are stated as follows:

2: sp hybridisation3: sp2 hybridisation4: sp3 hybridisation5: hybridisation

The formula because that finding the number is,Hybridization Number: number of valence electron + monovalent + (negative charge) – (positive charge)/2The valence electron of the iodine atoms are 7 as there is seven electron in the outermost shell. The number of the monovalent atom is two as the two out of 3 iodines room monovalent. Currently when we come to the fee of the I3- ion it has a an unfavorable charge so the worth of this an adverse charge will be 1.

Now place all the values according to the formula,7+1+2/2=10/2=5Thus the hybridisation number is 5 which means it’s hybridisation is sp3d.

Another way of detect the hybridisation that a given molecule is v the aid of lone pairs and also valence electrons. The variety of lone pairs in this molecule is 3, and the number of atoms sharing valence electron is 2.Hence, 3+2=5 which likewise determines sp3d hybridisation.

The form of I3- Ion


The shape of the molecule I3- is Linear. There are three Iodine atoms the end of i beg your pardon one has actually an extra an unfavorable charge. Due to this one extra electron over there 3 lone pairs of electrons and also 2 bond pairs making it’s steric number 5. Together there are three lone pairs on the central Iodide atom, these pairs try to defeat each other as lot as possible. So in order come be far at a better distance, the pairs take the equatorial positions, and the various other two Iodine atoms room 180 levels from one another. For this reason the in its entirety shape of the I3- ion is linear.


So below is the tricky component about this ion, an initial of all prefer it as a charge on it we can call it together a polyatomic ion rather of calling it a molecule. Ions are the fees we see on the molecules. Together I3- has one electron, this Ion has actually a an unfavorable charge overall. Molecules have polarity since it has both the fees that space a partly positively fee end and also the partially negatively charged end. Over there is a dipole moment on the molecules relying on the separation that the fees on the molecule. If the distance between both the dues is bigger the dipole moment will also be larger.

But once we talk around I3- ion the is a negatively fee ion. Also when us draw, it’s Lewis structure we carry out not see any type of dipole moment or the polar bond in it as the overall charge itself is an unfavorable on the ion. So it is no polar or nonpolar. However, if you have actually to explain the ion, you deserve to use the phrase the “ choose a polar molecule” since I3- is dissolve in water.

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In finish remarks, to amount up, this whole article, I3- is a polyatomic ion that has 22 valence electrons, 3 lone pairs, 2 bond pairs, and also sp3d hybridization. The is linear in shape and has no polarity.