The lewis structure of ash3 shows __ nonbonding electron pair(s) on as.
The Correct Answer and Explanation is:
The Lewis structure of AsH₃ (arsine) shows 1 nonbonding electron pair on arsenic (As).
Explanation:
The Lewis structure represents the arrangement of atoms and electrons in a molecule, showing how atoms are bonded together and how the valence electrons are distributed. To understand the number of nonbonding electron pairs on arsenic in AsH₃, let’s break down the process step-by-step:
- Valence Electrons of Arsenic and Hydrogen:
- Arsenic (As) is in Group 15 of the periodic table, so it has 5 valence electrons.
- Hydrogen (H) is in Group 1 and each hydrogen atom has 1 valence electron.
- Total Valence Electrons:
The total number of valence electrons in AsH₃ is calculated as follows:
- Arsenic: 1 × 5 = 5 electrons
- Hydrogen: 3 × 1 = 3 electrons
Total = 5 (from As) + 3 (from H) = 8 valence electrons.
- Electron Distribution in the Lewis Structure:
- In the Lewis structure of AsH₃, arsenic will be the central atom because it is less electronegative than hydrogen.
- Three single bonds are formed between arsenic and the three hydrogen atoms. Each bond uses two electrons, totaling 6 electrons (3 bonds × 2 electrons).
- After forming the bonds, 2 electrons remain. These 2 electrons will be placed as a nonbonding pair (lone pair) on arsenic.
- Resulting Lewis Structure:
- The structure has arsenic in the center with three hydrogen atoms bonded to it via single bonds.
- Arsenic will have one lone pair of electrons and will not have a full octet (it will have 8 electrons in its valence shell: 6 from the three bonds and 2 from the lone pair).
- Each hydrogen atom forms a single bond with arsenic and has a full valence shell (2 electrons each).
Thus, in the Lewis structure of AsH₃, arsenic has one nonbonding electron pair.
This results in a trigonal pyramidal molecular geometry, similar to ammonia (NH₃), where the lone pair on arsenic pushes the bonds slightly downward, giving the molecule its 3D shape.