Answer:
In the orthotellurate anion (TeO4^2-), the central atom is tellurium (Te). To determine the number of electron groups around the central tellurium atom, you should consider both the number of bonding pairs and lone pairs of electrons.
1. There are four oxygen atoms bonded to the central tellurium atom in the orthotellurate ion. Each bond consists of two electrons, one from tellurium and one from oxygen. So, there are 4 * 2 = 8 electrons from the bonding pairs.
2. Additionally, the orthotellurate ion has a 2- charge, indicating that it has gained two extra electrons. These electrons are represented as two lone pairs around the tellurium atom.
Therefore, there are 8 electrons from the bonding pairs and 2 electrons from the lone pairs, totaling 10 electron groups around the central tellurium atom in the orthotellurate ion.