What is the molecular geometry (shape) if you have 3 single bonds and 1 lone pair around the central atom?
Like NH3. trigonal pyramidal
To determine the molecular geometry (shape) in this case, you need to follow a few steps:
Step 1: Determine the central atom. In this case, as you stated, the central atom has 3 single bonds and 1 lone pair.
Step 2: Count the total number of electron pairs around the central atom. Since there are 3 single bonds and 1 lone pair, the total number of electron pairs will be 3 + 1 = 4.
Step 3: Determine the electron pair geometry. To do this, use the VSEPR (Valence Shell Electron Pair Repulsion) theory. According to this theory, electron pairs, whether bonding or lone pairs, repel each other and try to be as far apart as possible to minimize repulsion. In this case, with 4 electron pairs, the electron pair geometry will be tetrahedral.
Step 4: Determine the molecular geometry (shape) by considering both the bonding and lone pairs. Since there is 1 lone pair, it will take up more space than the bonding pairs due to greater repulsion. Therefore, it will push the bonded electron pairs closer together, resulting in a change in the molecular geometry.
Based on this, the molecular geometry (shape) will be trigonal pyramid. The three single bonds will be arranged in a triangular plane, while the lone pair will occupy a position above or below this plane, resulting in a pyramid-like shape.