H2P-Br2 What is the electron dot structure

H2P-Br2 What is the electron dot structure

The Correct Answer and Explanation is:

The electron dot structure for the molecule H₂P-Br₂ (which I assume refers to dihydrogen phosphine dibromide) involves understanding the bonding between hydrogen (H), phosphorus (P), and bromine (Br). Here’s how to draw it and explain the bonding:

Step-by-Step Process:

1. Count the Total Number of Valence Electrons:
   • Hydrogen (H): Each hydrogen atom has 1 valence electron, so for 2 hydrogens, this gives 2 electrons.
   • Phosphorus (P): Phosphorus has 5 valence electrons.
   • Bromine (Br): Each bromine atom has 7 valence electrons, so for 2 bromines, this gives 14 electrons.
   Total valence electrons = 2 (from H) + 5 (from P) + 14 (from Br) = 21 electrons.
2. Determine the Bonding:
   • Phosphorus (P) will form single bonds with two hydrogen atoms and two bromine atoms.
   • Each single bond consists of 2 electrons, so 4 electrons are used in the P-H and P-Br bonds.
3. Place the Electrons:
   • Start by placing the P atom in the center, as it is the least electronegative.
   • Connect the two hydrogen atoms to phosphorus with single bonds (P-H).
   • Connect the two bromine atoms to phosphorus with single bonds (P-Br).
4. Distribute the Remaining Electrons:
   • After forming the bonds, you’ll have 21 total electrons, 4 electrons already used in the bonds.
   • This leaves you with 17 electrons to distribute.
   • Place 6 electrons (3 lone pairs) around each bromine atom to complete their octets.
   • Finally, place the remaining electrons as lone pairs around the phosphorus atom. Since phosphorus only needs 8 electrons (but it can have more in its valence shell), any leftover electrons go as lone pairs on phosphorus.

Electron Dot Structure:

 H  H
 \ /
  P
 / \
Br  Br

Each bond represents a pair of electrons, and the lone pairs of electrons are not shown in this structure, but they exist around the phosphorus and bromine atoms. Phosphorus, in this case, has an expanded octet, meaning it can accommodate more than 8 electrons.

Explanation:

In H₂P-Br₂, the phosphorus atom uses its 5 valence electrons to form bonds with hydrogen and bromine. The hydrogens each provide one electron, while each bromine provides 7. The remaining electrons around the bromines and phosphorus ensure that each atom achieves a stable configuration (hydrogen with 2 electrons, and bromine and phosphorus with 8 or more electrons). This structure fits the rules of chemical bonding, taking into account the octet rule and the ability of phosphorus to expand its valence shell.