GaCl3 Lewis Structure, Characteristics: 19 Facts You Should Know


In this article, we discuss trichloride of group 13th element. Let’s discuss GaCl3 lewis structure and different important facts.

GaCl3 or gallium trichloride is an example of trihalide of group 13th element. Ga is very stable in its +3 oxidation state because at that state its electronic configuration will be d10. Ga is the main group metal so it has an affinity to bind with electronegative atoms like Cl. Due to electron deficiency, GaCl3 is exist as a dimer form in solid-state, Ga2Cl6 like Al2Cl6.  In the dimer form, it will form a 3c-4e bond.

GaCl3 has a high boiling point and very low melting point. GaCl3 is sp2 hybridized. Ga has filled d electrons so 4s and 4p orbitals participate in the hybridization or any kind of bond formation. The low oxidation state of Ga can permit to involved in complex formation for the GaCl3.

1.    How to draw GaCl3 lewis structure?

For a p block element or any kind of element that can form a molecule, it is necessary to draw their lewis structure to observe the bond structure, bonding, method, etc. Let us consider drawing the GaCl3 lewis structure.

GaCl3 lewis structure
GaCl3 Lewis Structure

Step 1- The first step is counting the valence electrons of every atom in the molecule and added together. So first we calculate the valence electrons in the GaCl3 lewis structure. Ga is p block group 13th element. The electronic configuration of Ga is [Ar]3d104s24p1. So, it has a vacant d orbital and three valence electrons in the 4 s and 4 p orbitals. Again, Cl is also a p block element but it belongs to the halogen family group 17th element. The configuration of Cl is [Ne]3s23p5. So, it has seven electrons in its valence shell. So total valence electrons in the GaCl3 lewis structure is 3+(7*3)=24 electrons.

Step 2 – in the 2nd step, we have to decide on the central atom of any molecule. In the GaCl3 lewis structure, Ga is a p block metal so it shows a positive charge, so its electronegativity is very low and for this reason, Ga will be chosen as the central atom in the GaCl3 lewis structure. Three Cl atoms are present on the three sides of the central Ga atoms.

Step 3 – In this step, we have to calculate how many numbers of bonds are required according to the Octet rule. According to the octet rule every p block elements try to complete its valence shell by eight electrons. So, for the  GaCl3 lewis structure electrons needed according to the octet rule will be, 8*4 =32 electrons. In the solid-state, GaCl3 exists as a dimer, so in the dimer, the electrons needed will double from the monomer. So, the electrons needed will be 32*2 = 64 electrons.

But the valence electrons for the GaCl3 monomer will be 24 and for the dimer, it will be 24*2 =48 electrons. In the dimer, there will be a metal-metal double bond and there are four electrons will be needed.  So, in the GaCl3 dimer required bonds apart from metal-metal bonds will be, 1/2(64-4-48) = 6 bonds, and in the GaCl3 monomer the required bonds will be 3 bonds.

Step-4 In the fourth step we added all the atoms by the required number of bonds. In the GaCl3 lewis structure, there will be a minimum of three bonds are there so, Ga and three Cl atoms are attached via three single bonds.

Step-5 In this step we try to fulfill the octet of every atom in the GaCl3 lewis structure. After adding the three bonds the octet of Ga is completed via the formation of a dimer. But for the Cl, six electrons exist in their valence shell and for completing the octet they exist as lone pairs over the Cl atoms.

2.    GaCl3 lewis structure shape?

The shape of the molecule depends on the hybridization, mode of bonding, and presence of surrounding atoms. There are three surrounding atoms for Ga in GaCl3 lewis structure, so the acceptable shape is planar trigonal.

GaCl3 Shape

Ga is a p block element and has only three electrons in its valence shell and they are forming a bond with three Cl atoms. There are no other electrons are present in the valence shell of Ga in the GaCl3 lewis structure. GaCl3 is an AX3 type of molecule without lone pairs of central atoms, so according to the VSEPR theory, it should adopt planar trigonal geometry. Again, from hybridization, we can say that if the central atom is sp2 hybridized so the shape of the molecule will be planar trigonal.

3.    GaCl3 lewis structure angle?

For a planar trigonal molecule, a bond angle is expected to be 1200. If there is no deviation factor present, like lone pairs -bond pair repulsion, the large size of surrounding atoms, etc. In the GaCl3 the Cl-Ga-Cl bond angle is 1200.

GaCl3 Bond Angle

In the GaCl3 lewis structure, Cl-Ga-Cl is around 1200. So, it is evident from the structure of GaCl3 that it is planar trigonal and there is no lone pair-bond pair repulsion. Actually, in the GaCl3 lewis structure, there is no deviation factor is present, so the bond angle is ideally 1200.

4.    GaCl3 valence electrons

The number of valence electrons for GaCl3 lewis structure is calculated for Ga and three Cl atoms individually. Ga and Cl both are p block elements, so we only count the electrons in the p orbitals, because those electrons are the valence electrons for GaCl3.

GaCl3 Valence Electrons

In the GaC3 lewis structure, Ga and Cl have three and seven electrons in their valence shell respectively. The electronic configuration of Ga and Cl are[Ar]3d104s24pand  [Ne]3s23p5 respectively. So, the total valence electrons in the GaCl3 lewis structure are, 3+(7*3)=24

5.    GaCl3 lewis structure lone pairs

In the GaCl3lewis structure, only cl atoms have the lone pairs, not central Ga. All the valence electrons of Ga are involved in the bond formation.

GaCl3 Lone Pairs

From the electronic configuration, it is evident that there are only three electrons in the valence shell for Ga and all the electrons are involved in the bond formation and no electrons are there in the valence shell of Ga. So, Ga is lack of lone pair.

But Cl has seven electrons in its valence orbitals so, it has seven valence electrons and only one electron is involved in the bond formation and the rest of the six electrons exist as three pairs of lone pairs. So, there are only Cl atoms containing lone pairs in the GaCl3 lewis structure.

So, the total lone pairs in the gaCl3 lewis structure are 3*3 = 9 pairs of lone pairs.

6.      GaCl3 lewis structure formal charge

GaCl3 lewis structure is partially charged or neutral is predicted from its formal charge value. Accounting for the same electronegativity for Ga and Cl we should calculate the formal charge of the molecule.

It is a theoretical concept, so formal charge has a specific formula, and the formula is,

F.C. = Nv – Nl.p. -1/2 Nb.p.

The formal charge over Ga is, 3-0-(6/2) = 0

The formal charge over Cl is, 7-6-(2/2) = 0

So, the GaCl3 lewis structure is neutral from its formal charge value.

7.    GaCl3 lewis structure octet rule

In the GaCl3 lewis structure, only Cl has completed its octet by completing the valence shell with eight electrons, and Ga is not completed its octet.

Dimer of GaCl3

Cl has seven electrons in its valence shell and it shares one bond via two electrons with Ga and completed its octet to make a single bond. But in the case of Ga, there are three electrons in the valence shell and Ga makes three bonds with shre three more electrons, so there are six electrons in the valence shell of Ga and it is not complete its octet. That’s why Ga can accept more electrons to fulfill its electron deficiency and makes dimer to complete the octet.

When it forms a dimer then both Ga atoms in dimer form complete their octet via bridging the cl atoms. This model can be explained via 3c-4e bonding.

8.    GaCl3 lewis structure resonance

There are no such electron clouds present over the Ga atoms for delocalization in different skeleton forms. That’s why the GaCl3 lewis structure does not show any resonating structure.

9.    GaCl3 hybridization

From the shape of the molecule and involvement of the orbital, we can say that GaCl3 lewis structure is sp2 hybridized.

We can calculate the GaCl3 hybridization by using the following formula,

H = 0.5(V+M-C+A)

In the GaCl3 lewis structure, the central Ga atom is, ½(3+3+0+0) =3 (sp2 hybridized).

If the central atom of a molecule is involved in three orbitals in hybridization then it will be sp2 hybridized.

Let us understand the hybridization of GaCl3 lewis structure,

GaCl3 Hybridization

From the box diagram of the GaCl3 lewis structure, it is evident that central Ga is sp2 hybridized where only 4s and 4p orbitals are involved and there are vacant p orbitals in Ga, so the GaCl3 monomer does not complete its octet.

10.    GaCl3 solubility

GaCl3 is soluble in the following solvents,

  • Water
  • Benzene
  • CCl4
  • CS2

11.    Is GaCl3 soluble in water?

As discussed, the previous GaCl3 is very much soluble in water, as it vacant p orbital so there the lone pairs of oxygen atom can be attacked and for this reason, it can produce an adduct and result is soluble in water. GaCl3 is very moisture sensitive.

12.    Is GaCl3 a strong electrolyte?

Yes, GaCl3 is a very strong electrolyte, in an aqueous solute, the ion can readily be ionized to Ga3+ and 3Cl, both ions are good conductors of electricity and both are soluble in water, making the solution a good conductor of electricity.

13.    Is GaCl3 polar or nonpolar?

GaCl3 is dissolved in water, so it is a sign that GaCl3 is a polar molecule. The electronegativity difference between GA and Cl is huge which makes the molecule polar. Again, due to the asymmetric shape, the mackerel has some resultant dipole moment.

14.    Is GaCl3 acidic or basic?

GaCl3 is acidic, rather it is a very strong Lewis acid.

15. Is GaCl3 a lewis acid or base?

In the GaCl3 lewis structure, there is a vacant p orbital present for Ga, this p orbital is energetically accessible and it can take electrons or lone pairs from a suitable lewis base and acts as stronger lewis acid, But in the dimer from the vacant p orbital is filled upon bond formation so, the dimer is not a good lewis acid.

16. Is GaCl3 paramagnetic or diamagnetic?

After the bond formation all the valence electrons of GaCL3 and even for Ga(III_ all the d electrons are paired up. So, Gacl3 or Ga(III) is diamagnetic in nature.

17. Is GaCl3 linear?

No, GaCl3 is not linear, the GaCL3 lewis structure shape is trigonal planar and it is evident from the bond angle and its hybridization value too.

18. GaCl3 bond angle

The GaCl3 lewis structure shape is trigonal planar and the hybridization value is sp2, so the bond angle is 1200.

19. GaCl3 boiling point

The boiling point of GaCl3 is very high because in the solid state two Ga centers are linked strongly and the solid is liquified. In the liquid state since Ga-Ga bonds are extremely strong at the very high temperature required to break those bonds, Thus, it has a very high boiling point.

Conclusion

In the GaCl3 lewis structure, Ga is sp2 hybridized but there is electron deficiency in the Ga center and to fulfill, the deficiency GaCl3 is exist as a dimer form via 3c-4e bonding.

Biswarup Chandra Dey

Chemistry is not all about reading line by line and memorize, it is a concept to understand in easy way and here I am share with you the concept about chemistry which I learn because knowledge is worth to share it.

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