How many atoms or sets of lone pairs surround the central atom in CH3NH2? State the name of its structure geometry.

In CH₃NH₂ (methylamine), the central atom is nitrogen (N). To determine how many atoms or sets of lone pairs surround the nitrogen atom, we need to consider its bonding.

The nitrogen atom is bonded to two hydrogen atoms from the amine group (NH₂) and one carbon atom (from the CH₃ group). Therefore, there are three bonding pairs of electrons. However, nitrogen also has one lone pair of electrons. Thus, the total number of ‘electron pairs’ around the nitrogen atom is four: three bonding pairs and one lone pair.

So, to summarize, the central nitrogen atom in CH₃NH₂ is surrounded by three atoms (two hydrogens and one carbon) and one lone pair. This configuration leads to a total of four electron pairs.

The geometry of this molecule is described as tetrahedral due to the four areas of electron density around the nitrogen atom. However, because one of these areas is a lone pair, the actual molecular geometry is called trigonal pyramidal.