Multiple Choice
Which of the following best describes the Lewis dot structure for the NH_2^- ion?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Ions
Multiple Choice
Which of the following correctly describes the Lewis dot structure for the BeH2 molecule?
A
Beryllium is bonded to two hydrogen atoms with single bonds, and there are two lone pairs on each hydrogen.
B
Beryllium is bonded to two hydrogen atoms with double bonds, and there are two lone pairs on beryllium.
C
Beryllium is bonded to two hydrogen atoms with single bonds, and there are no lone pairs on beryllium.
D
Beryllium is bonded to one hydrogen atom with a single bond and has three lone pairs.
Verified step by step guidance1
Step 1: Determine the total number of valence electrons in the BeH2 molecule. Beryllium (Be) has 2 valence electrons, and each hydrogen (H) has 1 valence electron, so total valence electrons = 2 + 2(1) = 4.
Step 2: Arrange the atoms with beryllium as the central atom bonded to two hydrogen atoms. Since Be is less electronegative, it will be the central atom.
Step 3: Form single bonds between beryllium and each hydrogen atom. Each single bond consists of 2 electrons, so 2 bonds use 4 electrons, which accounts for all valence electrons.
Step 4: Check for lone pairs on each atom. Since all 4 valence electrons are used in bonding, there are no lone pairs on beryllium or hydrogen atoms.
Step 5: Confirm the octet rule or duet rule. Hydrogen atoms follow the duet rule and have 2 electrons each from the single bond, and beryllium has only 4 electrons around it, which is typical for Be in such compounds.
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