This article is about the Lewis structure of BrF5, the Molecular geometry of BrF5, hybridization and the Formal charge present on BrF5.
What is Lewis’s structure and why is it essential to study Lewis’s structure in chemistry?
The valence shell electrons of a molecule are depicted in a Lewis Structure, which is a simplified representation. It’s used to illustrate how electrons in a molecule are distributed around specific atoms. When two atoms are bonded, electrons are shown as “dots” or as a line between them. The main goal of Lewis Structure is to find the “optimal” electron configuration, which requires that the octet rule and formal charges be maintained.
Famous scientist Gilbert N Lewis initially proposed the Lewis structure in his journal “The Atom and the Molecule” in 1916. The Lewis structure in chemistry is essential because it can predict the number of bonds, nonbonding electrons, and bonding electron structure.
Note: Lewis’s structure does not try to explain the molecular shape, bond formation, or electron sharing between atoms. It is the most basic and limiting explanation of the electrical structure.
Introduction of Bromine Pentafluoride (BrF5)
Bromine pentafluoride, or BrF5, is a bromine fluoride that is an interhalogen compound containing solely halogen atoms. It is a colourless, fuming chemical with a strong odour while it’s liquid. Bromine pentafluoride is highly harmful to humans and should never be ingested since it corrodes the eyes and inner membranes.
The electrons in an atom’s outermost shell, or energy level, are known as valence electrons. To study the Lewis Structure of any molecule, it is essential to understand the electrons present in the valence shell.
Lewis Structure of Bromine Pentafluoride (BrF5)
Any molecule’s Lewis Dot structure is a graphical representation of the atoms that make up the structure and their respective valence electrons. This structure lets us understand the molecule’s bond forms and electron arrangement.
To learn about the Lewis structure of BrF5 (Bromine pentafluoride), we must first learn about the Lewis diagrams of the atoms involved. Bromine has an atomic number of 35 and an electronic configuration of 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5.
To study the Lewis structure in chemistry, it is essential to understand the total number of valence shells present in the outer shell. In the case of Bromine, there are 4s2 and 4p5 shells which are participating in bond formation, so there is a total of seven valence electrons present in Bromine.
Apart from that, Fluorine has an atomic number of 9 and an electronic configuration of 1s2 2s2 2p5 in BrF5. The highest principle energy level contains valence electrons, and the total number can be estimated by adding electrons in the sublevels of those principal high energy levels.
To get a total of 7 valence electrons, we need to add 2 electrons from the 2s and 5 from the 2p.
Steps to remember while drawing Lewis Structure:
There are a few general steps to follow to draw a Lewis structure of a molecule. The number of steps can be adjusted depending on the molecule or ion’s complexity. We’ll look at each stage of drawing the Lewis structure of Brf5 now.
- Calculate the total number of electrons in the valence shells of the Bromine and fluorine atoms.
- Total electron pairs exist as lone pairs and bonds.
- Choosing the centre atom
- Draw lone pairs.
- Mark charges on atoms.
- To acquire the optimum Lewis structure, check the stability and decrease atom charges by converting lone pairs to bonds.
Steps to Draw the Lewis Structure of bromine Pentafluoride (BrF5)
- Calculate the total number of electrons in the valence shells of the Bromine and fluorine atoms.
To draw the Lewis structure of BrF5, first, we must calculate the valence electrons present in BrF5. Seven valence electrons are present in Bromine, and seven electrons are present in each Fluorine. So, we can say that five Fluorine has 35 valence electrons, and by adding 35 with seven electrons of Bromine, we will get 42.
- Determine how many additional valence electrons one molecule of BrF5 requires:
Each participating atom requires one valence electron; thus, the total is six because there are six atoms in the BrF5molecule.
- Choosing the centre atom
Being the core atom of a molecule has its own set of criteria. The most significant aspects of being the centre atom are having a high valence and being the most electropositive atom.
The least electronegative atom must be placed in the centre. So, the central atom is Bromine because it is less electronegative than Fluorine.
- Draw lone pairs on atoms
The next step after choosing the central atom is to draw lone pairs on the atoms of a molecule. To draw lone pairs, it is crucial to remember how many total numbers of electrons are present. So, in the case of BrF5, ten electrons are participating in a single bond between Bromine and Fluorine.
After each participating fluorine atom’s octet has been completed, 40 valence electrons have been consumed. We’re still left with two valence electrons, which will be drawn as a lone pair on the bromine atom.
From the figure above, it can be seen that there are five sigma bonds (B__F) are present while 16 lone pairs can be marked on Bromine and fluorine atoms in BrF5.
Usually, the remaining electron pairs should be used to make marks on external atoms (in this case, on fluorine atoms). Then, on fluorine atoms, draw lone pairs as three lone pairs will be required for each fluorine atom. Therefore, 15 electron pairs are now present as lone pairs around the fluorine atoms. At the same time, there is one lone pair on Bromine.
- Mark and stabilize charges on atoms.
Using the following formula, we can calculate the format charge on the atoms.
formal charge = valence electrons – nonbonding electrons – 1/2 bonding electrons
Formal charge = 7 – 2 – 1/2 (10) = 0 for bromine atom.
Formal charge = 7 – 6 – 1/2 (2) = 0 for each fluorine atom.
Because neither the Bromine nor the fluorine atoms carry charges, there is no need to label the charges on BrF5.
And as we can see in the structure above, the central atom (Bromine) forms an octet. The octet rule is thus satisfied. As a result, this structure is BrF5’s stable Lewis structure.
Importance of Lewis Structure in Chemistry
Lewis structure of any molecule is essential because:
- It allows us to predict how and how many bonds it will form. This understanding will eventually allow us to identify molecule forms and chemical characteristics.
Molecular Geometry and Shape of the Bromine Pentafluoride (BrF5)
Molecular Geometry of BrF5
Molecular geometry or molecular structure refers to the three-dimensional shape or arrangement of atoms in a molecule. Understanding a compound’s molecular structure can help determine its polarity, reactivity, phase of matter, colour, magnetism, and biological activity.
The molecular geometry of BrF5 can be explained with the help of the VESPR theory.
According to this theory, the total number of bonding and nonbonding electrons, as well as their orientation around the core atom, determine the overall form of a molecule.
These atoms are arranged so that there is very little repulsion between them. It’s essential to recognize that the electrons orbiting the core atom tend to keep a safe distance from one another. BrF5’s structure could have been an octahedron, but the presence of a lone pair of electrons causes it to rearrange into a square pyramidal shape.
The lone pair of electrons has the most repelling impact because they are closer to the core atom than the bonded pair of electrons.
Their repulsive impact is much more substantial than the bonding pair of electrons.
The Geometry of BrF5 Molecule by AXN Notion:
The basic geometry of the molecule or ion will be described using the AXN notation, where A represents the core atom Bromine in this case, and X represents the terminal atoms singly-bound to the central atom Fluorine. The number of lone pairs is indicated by the letter “n. “
Bond Angle and Shape of BrF5
In BrF5, the bond angle is 90 while the structure of BrF5 is square pyramidal
According to the VSEPR theory, the Fluorine atoms repel one another, resulting in a Trigonal Bipyramidal structure for the molecule. However, the Fluorine atoms are pushed in, even more, when the lone pair is added. This results in a Square Pyramidal form for the BrF5.
So, we can say that the molecular geometry of BrF5 has a square pyramidal and an octahedral electronic structure as a result.
The polarity of compounds and factors affecting polarity
Polarity of BrF5
When we examine a compound’s structure and properties in-depth, the compound’s polarity is a significant topic of discussion.
The separation of electric charge that results in one negatively charged and one positively charged end is known as polarity. Because of the difference in the electronegativity values of the involved atoms, this charge separation causes a net dipole moment on the overall molecule.
The strength with which a molecule attracts a shared pair of electrons towards itself is determined by the value of its net dipole moment, which can be positive or negative.
BrF5 is a polar molecule because of its asymmetric structure, which causes an unequal charge distribution around atoms, making it harder to cancel out the dipole along with five Br-F bonds, leading to a net dipole moment. As a result, BrF5 has a polar structure.
Factors Affecting Polarity:
The stronger the atom’s ability to attract bound electrons, the higher its electronegativity. As a result, the difference between the electronegativity of atoms is precisely proportional to the polarity of a molecule.
The dipole moment is a measurement used to determine the level of polarity. A molecule’s polarity increases as its dipole moment increase.
A molecule’s polarity and dipole moment are proportional
A molecule’s geometrical shape plays a significant role in defining its polarity. The molecules that have a symmetrical form have a dipole moment of zero. If a molecule contains a polar bond, the dipole moment of the molecules cancels out, resulting in a nonpolar molecule.
Hybridization of BrF5
The orbitals involved and the bonds produced during the interaction of bromine and fluorine molecules will be examined to determine the hybridization of bromine pentafluoride.
Hybridization in BrF5 is sp3d2 because one 4s, three 4p, and two 4d orbitals participate in mixing and overlapping, resulting in new hybrid orbitals. Some of the valence electrons in bromine shift to the 4d orbitals to acquire a pentavalent position.
Because of the two unpaired p orbitals, the bromine atom becomes excited. It is at this point that the hybridization process begins. With the help of sigma bonds, the bromine atom’s remaining five valence electrons connect with the five fluorine atoms, leaving a lone pair of electrons in one of the newly formed hybrid orbitals.
When hybridization process occurs?
It is essential to realize that hybridization occurs when atomic orbitals of a similar energy mix and overlap like that of an s orbital with a p orbital or a s orbital with a d orbital.
Within a molecule, energy redistribution occurs among similar energy orbitals of individual atoms, resulting in the creation of new hybrid orbitals of equivalent energy.
Characteristics of BrF5
|Boiling point||106°F at 760 mmHg|
|Vapour pressure||328 mmHg|
|Solubility in Water||Reacts with water violently|
Chemical Characteristics of BrF5
- BrF5 is colourless in the liquid state
- It has a pungent odour
- It is highly toxic and corrosive.
- BrF5 is a colourless gas at temperatures above boiling point.
Uses of BrF5
- BrF5 is used in uranium processing as a fluorinating agent
- It is used as an oxidizer in some rocket propellants.
- BrF5 is used to make fluorocarbons.
Hazards of BrF5
- Hazards to Health
- Bromine pentafluoride is active and poisonous and is extremely harmful to the skin.
- The fumes irritate the eyes, skin, and mucous membranes severely.
- Nephrosis and hepatitis can develop as a result of long-term exposure. A few drops in the mouth can cause serious corrosion and burns.
- Hazards of fire
- Bromine pentafluoride is a highly reactive chemical.
- When it comes into contact with water, it explodes, releasing deadly and caustic gases.
- When it comes into contact with acids, it decomposes, releasing deadly Bromine and fluorine gases.
- When using concentrated nitric or sulfuric acid, the reaction is extremely violent.
- Organic compounds such as carboxylic acids, alcohols, ethers, hydrocarbons, grease, wax, and cellulose react aggressively with bromine pentafluoride.
- When these or any other organic substance is mixed with them, spontaneous burning and/or explosion might occur.
- Explosions can occur when metals are in powder form and/or when they are heated. Ignition occurs when the temperature is below freezing.
The article is about the Lewis structure of BrF5 and its importance in chemistry. It is revealed that there is an abnormality in the bromine atom in this case. The abnormality is that its octet has been expanded to accommodate 12 valence electrons instead of 8. As a result, the 5 fluoride atoms may form a single covalent link with the bromine atom, leaving a lone pair of electrons behind.
This lone pair modified the molecular geometry of BrF5 (Bromine pentafluoride) to square pyramidal form octahedral. It is critical to recognize that electron geometry is an octahedron, and there is no reason to mix the two.
Furthermore, bromine hybridization in BrF5 is sp3d2 because one 4s, three 4p, and two 4d orbitals participate in the mixing and overlapping, resulting in new hybrid orbitals.
Finally, the presence of a net dipole moment, mainly due to a lone pair of electrons on the bromine atom, makes the bromine pentafluoride molecule polar. Different factors can affect the polarity of the molecule or atom. BrF5 can be hazardous to health because of its explosive and reactive nature.
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