Oxybromide (OBr2) has a central oxygen (O) atom with 6 valence electrons, forming single bonds with two bromine (Br) atoms, each contributing 7 valence electrons. The Lewis structure shows two single O-Br bonds and two lone pairs on the oxygen atom, using 20 valence electrons in total. OBr2 adopts a bent molecular geometry with a bond angle slightly less than 109.5°, influenced by lone pair-bond pair repulsion. The O-Br bonds are polar due to the electronegativity difference (O: 3.44, Br: 2.96), making the molecule polar overall. This structure affects its chemical reactivity and potential use in halogenation reactions.
By the arrangement of the outer most shell electrons, the most energetically stabilized Structure of the obr2 lewis structure can be determined. In a lewis structure loosely bounded electrons by nuclear force are shown around the atomic symbols.
How to draw lewis structure for OBR2
In obr2 Lewis structure we see a basic diagram where the O-Br bonding skeleton of the molecule is shown.
With using the atomic symbols of Oxygen and Bromine, the obr2 lewis structure shows the position of the atoms in the molecule with excess electrons (beside bonding electrons) around the particular atom.
In modern Periodic table Oxygen is in group16 and Bromine is in group 17. The electrons in the last orbit of Oxygen atom is [He] 2s2 2p4. Electronic arrangement of Bromine atom is [Ar] 3d10 4s2 4p5.
In the outer orbit energy levels of the Oxygen and Bromine atoms, total twenty negatively charged particles (7 + 7 + 6) are available means ten pairs of electron for bond formation in the obr2 lewis structure.
Oxygen is in the center of the obr2 electron dot structure and two Bromine atom connected to the opposite side from the central atom. After this arrangement; valence electrons are placed according to their parent atom.
To cover the last orbit with eight electrons, Oxygen and Bromine atoms share electrons cloud. To make a single bond, two electron cloud are joined, that is shown by a single line in obr2 lewis structure.
In this above obr2 lewis structure, both Oxygen and Bromine atoms have total eight pairs of excess unshared electrons.
OBR2 lewis structure shape
According to the Valence bond theory shape of a molecule is the distorted form of the geometry of the molecule if the central atom contains any unshared electron pair.
The VSEPR theory states with greater charge density the repulsion capability of lone pair electron cloud is greater than the bonding electron pair cloud. The center atom Oxygen has two pairs of non bonding electron cloud which occupies much space to create steric repulsion on the bonding electron cloud.
Oxygen atom in obr2 molecule has sp3 hybrid orbital so the related geometry would be like tetrahedral. But the electron cloud making steric repulsion disturbs the geometry and forms a bent shaped molecule.
OBR2 lewis structure formal charges
Formal charge is the charge density of an atom in a particular electron dot configuration, where it is assumed that the bonding electron cloud is equally distributed.
Formal charge of the atoms in obr2 lewis structure can be calculated by the equation, f = (n – lp – (bp/2)). Where ‘n’ is number of last orbit electrons, lp is unshared electrons and bp is bonding pairs electron of a particular atom.
From the Periodic table, we know that Oxygen atom has six electrons and Bromine atom has seven electrons in their last filled electronic shell. In the obr2 lewis structure each Bromine atom has three lone pairs where Oxygen atom has two pairs of non-bonding electron cloud.
Bromine atom formal charge in above obr2 electron dot structure, {7- 6 – (1/2×2)} = 0.
For Oxygen atom in the lewis structure formal charge is, {6- 4- (1/2×4)} = 0.
As the atoms of this above obr2 electron dot structure have “zero” formal charge, hence this obr2 lewis structure is very much stable in energetically as compared to the other possible structures.
OBR2 lewis structure lone pairs
A pair of electrons which remains unshared in a chemical bond formation is called lone pair. The lone pair electron cloud density only concentrates over containing atom.
To form obr2 lewis structure, twenty last filled orbit electrons of the three atoms are involved. Among these, two pairs (four electrons) of electron result in O-Br bond formation. Eight pairs of electrons are excess, these are lone pair electrons of Dibromine monoxide molecule.
Lone pair electron cloud remains in the control of only one atom, so near to its nucleus than the bonding electron cloud which spread over the average distance of the two bonding atoms. So this negatively charged cloud has high charge density compared to the bonding electron cloud.
That’s why Lone pair cloud is bulky in nature and creates strong steric repulsion. If central atom has the lone electron pair, its geometry becomes distorted.
OBR2 hybridization
According to the Valence bond theory atomic orbitals are intermixes to produce new hybrid orbital with different shape and energy which enhance the capacity of overlapping with other atomic orbital.
In the lowest energy level, Oxygen atom has two paired electrons in 2s and one 2p orbital. It also contains single spin electron in the two 2p orbital. These 2s and 2p orbitals of Oxygen atom intermixes to give sp3 hybridized orbital.
This sp3 hybrid orbital now makes greater overlap to the 4p Bromine orbital.
OBR2 lewis structure resonance
If the electrons which don’t participate in bond formation shift to vacant orbital of adjacent atom then we get a different electron dot structure, which is called resonance structure.
In the obr2 lewis structure both Oxygen and Bromine have extra electrons which not participate in bond formation. For shifting the electron cloud only Bromine atom has vacant 4d orbital in the 4th shell.
From the neutral electron dot structure, one non-bonding electron pair of Oxygen atom delocalizes to the Bromine atom vacant orbital. As the shifting of electron cloud occurs from the central atom to the ligand atom, this is called back bonding.
For this 2pπ (O) – 4dπ (Br) back bonding, partial double bond forms and we get the resonating structures of the Dibromine monoxide molecule.
OBR2 lewis structure octet rule
This rule states that the involving atoms of an electron dot structure orient themselves in a way that they share electron cloud and their outer energy level shell contain eight electrons. This arrangement of the electronic cloud gives stabilization.
Oxygen have six electrons in its outer s and p orbital od 2nd shell, where Bromine atom has seven electrons in the s and p orbital of 4th shell.
They share the electron cloud in such a way that each of them full fills the margin up to eight electrons in the outer shell. Hence the sp3 orbital of Oxygen atom overlap with the 4p orbital of Bromine to satisfy the rule.
OBR2 polar or nonpolar
Dipole moment (µ) causes polarity in a bond, which can be calculated by product of the separated charge (δ) and distance between charges (r) in the bond.
In the Dibromine monoxide molecule, electro-negativity of Oxygen (O) is 3.44 and that of Bromine is 2.96 on the basis of Pauling scale. This difference in the capacity of the bond electron cloud pulling creates charge separation in bond and Dibromine monoxide becomes polar molecule.
If this electro-negativity difference is 0.4 or more than that a charge separation occurs in the bond, which results a dipole, means one end of the bond becomes slightly negative than the other end. This dipole is a vector component directed towards the negative end.
The direction of dipole is towards the atom with greater tendency of pulling the bonding electron cloud, the Oxygen atom. More over this atom has lone electron pairs cloud which also increases the amount of electron dipole towards it.
For the steric electronic repulsion the shape of the molecule becomes bent. Hence the obr2 lewis structure has a net electronic dipole vector which makes the molecule polar.
OBR2 lewis structure bond angle
In an electron dot structure of a molecule the angle between two adjacent bonds (bond angle) can be calculated mathematically by the dot product of vectors.
The central atom Oxygen is sp3 hybridized, so the possible bond angle in the obr2 lewis structures is 109.5̊. But because of the presence of the electron pairs over this atom which don’t take part in bonding, the geometrical angle distorted.
The non-bonding electrons of the Oxygen atom involves in the 2pπ (O) – 4dπ (Br) back bonding with Bromine atom. The lone pair repulsion on the bonding electron cloud lowers. As partial double bond forms, steric repulsion of bonding electron cloud produces.
Bromine is in the 4th period in Periodic table with bulky electronic configuration. In the molecule both Bromine atoms have three pairs of unshared electron cloud. It higher the steric repulsion of bonding electron cloud.
As a whole the bond angle of the molecule increases to 112̊.
OBR2 lewis structure electron geometry
Theoretically we can predict the geometry of obr2 lewis structure by the assumptions of the Valence Shell Electron Pair Repulsion theory.
With the help of the hybridization of central atom, bond length, bond angle, general shape of the molecule we can predict the possible atomic position in a molecule. Various spectroscopic methods like UV-visible, IR, Raman, NMR, Electronic or Mass spectra can help to identify the geometry obr2 lewis structure.
In the obr2 lewis structure sigma (σ) bond is present in the both side of the central Oxygen atom which is sp3 hybridized with two pairs of unshared electron cloud. So this molecule can be generalized as AX2 type molecule with two single bonds and two non-bonding electron pair cloud.
From the VSEPR theory it can be said that this molecule belongs to the tetrahedral geometry group.
OBR2 valence electrons
The last filled energetic shell electrons are called valence electrons which can absorb energy to be in excited state where they can involve in chemical reactions.
In Obr2 lewis structure the three atoms contains twenty that type of electrons. Each bromine atom has seven electrons in the last filled 4s and 4p orbitals whereas the Oxygen atom has that type of six negatively charged particles in the 2nd orbit.
The electrons of the core orbitals in an atomic structure model are tightly bounded to the nucleus by strong nuclear force. With increasing the electronic energy level from the nucleus, the binding force lowers.
For this reason the outer shell electrons are loosely tied up and can move to higher energy level by taking up the provided energy.
OBR2 uses
Dibromine monoxide is used for bromination reactions where the radical form is produced to progress the reaction further.
The compound is only in a stable condition in very low temperature like (-40 ̊) or lower than this. Even it decomposes at room temperature. So not much uses of the compound is known.
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Hi…I am Triyasha Mondal, pursuing M.Sc in Chemistry. I am an enthusiastic learner. My specialization is in physical chemistry.
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