In BH 3, the total number of valence electrons is 6. But we can easily calculate it by just dividing a total number of valence electrons by two which will give the valence electrons pairs. The total number of valence electrons pairs for a molecule is equal to the addition of sigma bonds, pi bonds, and lone pairs present at the valence shells. Determine the total number of Valence electron pairs for BH 3 molecule.To determine the total number of valence electrons present in the BH 3 molecule has a total of 3 + 3*1=6 valence electrons. Similarly, the valence electron of hydrogen is 1, as hydrogen lies in the first group. Total of six valence electrons are found in the BH 3 molecule in which one boron atom share 3 valence electrons with three hydrogen atom sharing 3 valence electrons.īoron has a total of 3 valence electrons as it lies in the 13th group of the periodic table. Count the total number of valence electrons present on each atom of BH 3.A formula can be used to compute formal charge:ī = Number of bonded electrons Steps for drawing Lewis dot structure of BH 3 The Lewis diagram is more stable when the formal charge of an atom is lower. The formal charge is the result of when the number of valence electrons in the neutral atom subtracts the non-bonding electrons and then subtracting the number of bonds connected to that atom in the Lewis structure. There are some elements like Boron, Beryllium, Aluminum, Hydrogen, Helium, and Lithium that do not complete octet in their valence shell and become stable without eight electrons.Į.g.: Boron and Aluminum become stable with only six electrons on their valence shell. Hydrogen and helium are subject to the duplet rule. By gaining, losing, or sharing electrons, the atoms acquire the electronic configuration of the nearest noble gas. Hence this tendency of elements to form a chemical combinations and get stability. Similarly, hydrogen has only one electron in its outermost shell i.e one valence electron.Įlements having incomplete octets in their valence shell try to get inert gas configuration by transfer or mutual sharing of valence electrons. For example, boron has three electrons in its outermost shell which means boron has three valence electrons. They are either transferred or shared (completely or partially) for the bond formation. Valence electrons are those electrons that are present in the outermost shell of an atom and take part in chemical bonding. The central boron atom is surrounded by three hydrogen atoms to form a covalent bond. The electronegativity of the boron atom (2.04) is lower than the hydrogen atom (2.20) and it acts as a central atom. In a BH 3 molecule in which one boron atom shares valence electrons with three hydrogen atoms. A dot represents a lone pair of electrons and a straight line represents a bond pair of electrons. It provides information about the bond pair and lone pair of electrons in a molecule. It is a simple diagrammatic representation of molecule atoms bonding. The Lewis structure of the molecule is also known as the electron dot structure. Hence, in this stage BH 3 molecule is highly unstable and dimerized (B 2H 6) and gets stability. As a result, boron atom fails to complete its octet. So boron covalently combines with three hydrogens and share electrons with each other gains extra three electrons on boron fills six electrons in its outermost shell. Similarly, hydrogen has only one valence electron on its outermost shell. As we know that boron is the central atom and has only 3 electrons on outermost shell. In BH 3 molecule, Boron atom has an incomplete octet which can be understood by counting the valence electron of boron atom. Why borane is a highly unstable and reactive substance?
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |