4) Let's consider the electronic structure of the CBr4 molecule. Its central atom, C, has 4 electrons in its valence shell (you can see this from the Periodic Table, 2s22p2). Therefore, when four bromines share their four electrons with carbon, carbon atom has four electron pairs in the valence shell ( 4 pairs shared with bromines). In VSEPR notation, this molecule is described as AX4, where A is the central atom (carbon) and X is the atom linked to the central atom (four bromines). The electron-domain geometry of AX4 is tetrahedral. For this geometry, the angle is equal to 109.5°.
5) Let's consider the electronic structure of the TeBr4 molecule. Its central atom, Te, has 6 electrons in its valence shell (you can see this from the Periodic Table, 5s25p4). Therefore, when four bromines share their four electrons with tellurium, tellurium atom has five electron pairs in the valence shell ( 4 pairs shared with bromines and 1 non-bonding pair). In VSEPR notation, this molecule is described as AX4E, where A is the central atom (tellurium), X is the atom linked to the central atom (four bromines) and E is the lone pair ( 1 electron pair in this case). The electron-domain geometry of AX4E is trigonal bipyramidal (more exactly, seesaw).
Answer: 4)CBr4: tetrahedral electron-domain geometry with 0 non-bonding pairs on C.We confidently predict 109.5 degrees angles.
5)TeBr4: trigonal bipyramidal (more exactly, seesaw) electron-domain geometry with 1 non-bonding pair on Te will cause the bond angles to deviate from ideal values.