2. Given their electron configurations, identify the following elements and specify in what group of the periodic table do they belong: (a) [A13d104s24p4(b) [Rn]7s²(c) [Kr]4d10(d) [A]4s²3d8 3. Group the species that are isoelectronic: Be2+, F, Fe2+, N³-, He, S2', Co3+, Ar. 4. Two atoms have the electron configurations 1s2s2p6 and 1s22s2p63s1. The first ionization energy of one is 2080 kJ/mol, and that of the other is 496 kJ/mol. Pair each ionization energy with one of the given electron configurations. Justify your choice. 5. The bonds in beryllium hydride (BeH2) molecules are polar, and yet the dipole moment of the molecule is zero. Explain. 6. Predict and draw the molecular geometries (show bond angles) for these molecules: a. BH3 b. BrCl3 c. CF4

Identify each element below, and give the symbols of the other elements in its group:(a) [He] 2s²2p²(b) [Ar] 4s²³d³(c) [Ne] 3s²3p³

Valence electrons in an atom of phosphorus are closer to the nucleus than the valence electrons ofaluminum because: (A) P has a greater effective nuclear charge and a greater shielding than Al.(B) P has a greater effective nuclear charge with the same shielding as Al.(C) P has the same effective nuclear charge with greater shielding than Al.(D) P has the same effective nuclear charge and the same shielding as Al.

Describe and explain each of the following atomic properties of the representative group of elements in the periodic table: (a) The trends of atomic size left-to-right across period and top-to-bottom down the group; (b) The trends of ionization energy left-to-right across period and top-to-bottom down the group