Solutions to Practice Problems Week 3

1. Classify as a metal, nonmetal or metalloid: Cs, Os, Ge, He, I, Al

 

2. Determine the number of protons, electrons and neutrons for the following:

 

3. Show both nl^x and “boxes and arrows” electron configurations for each of the following: P, Fe, Tc

                                                  

                                                  

Note: There are discernible spaces between the boxes for s, p and d orbitals. These spaces are necessary to distinguish the identity of the electrons (the arrows). Without the spaces, the display cannot be interpreted.

 

4. For each of the following, give (a) the electron configuration using nl^x notation, (b) the number of unpaired electrons and (c) the orbital from which the first electron would be lost: sulfur, zinc, niobium (Nb) and tellurium (Te)

 

5. Give the family name (or group #) and the number of valence electrons in an atom of each of the following: Cs, Ge, At, Xe

 

• Cs: alkali metals (IA), one valence electron
• Ge: carbon group (IVA), four valence electrons
• At: the halogens (VIIA), seven valence electrons
• Xe: the rare gases (VIIIA), either zero or eight valence electrons

 

6. Circle the incorrect configurations below and then correct them.

 

Given	Correct
F: 1s22s22p5	OK
Mn: [Ar]4s24d5	Mn: [Ar]4s23d5
Rb: [Kr]5s1	OK
N: 1s22s22p	N: 1s22s22p3