Question

draw lewis structure for nh₄⁺, showing formal charges.

Explanation:

Step1: Count valence electrons

N has 5 valence - electrons and each H has 1 valence - electron. For $NH_{4}^{+}$, the total number of valence electrons is $5 + 4\times1-1=8$ (subtract 1 for the positive charge).

Step2: Determine the central atom

N is the central atom as H can only form one bond.

Step3: Connect atoms and distribute electrons

Connect the N atom to 4 H atoms with single bonds. Each single bond uses 2 electrons, so 8 electrons are used in 4 N - H single bonds.

Step4: Calculate formal charges

The formal charge on an atom is given by the formula $FC = V - N_{l.p.}- \frac{1}{2}N_{b.p.}$, where V is the number of valence electrons of the free atom, $N_{l.p.}$ is the number of non - bonding (lone pair) electrons, and $N_{b.p.}$ is the number of bonding electrons.
For N: $V = 5$, $N_{l.p.}=0$, $N_{b.p.}=8$. So, $FC = 5-0 - \frac{8}{2}=+ 1$.
For each H: $V = 1$, $N_{l.p.}=0$, $N_{b.p.}=2$. So, $FC = 1-0-\frac{2}{2}=0$.

The Lewis structure of $NH_{4}^{+}$ has N in the center with 4 single bonds to 4 H atoms. The formal charge on N is + 1 and on each H is 0.

Answer:

The Lewis structure of $NH_{4}^{+}$ has a nitrogen atom in the center bonded to four hydrogen atoms with single bonds. The formal charge on the nitrogen atom is + 1 and the formal charge on each hydrogen atom is 0.