Question

1. Please use the periodic table located below to help you formulate your answers. On the table, locate

the elements barium, phosphorus, and oxygen and then answer the questions below.
List the number of valence electrons each element has and explain how you know. Barium: 2, Phosphorus:
5, Oxygen: 6
b) Based on the number of valence electrons, write the monatomic lon (symbol with charge) each element may
form.
c) Phosphorus and oxygen can bond to form a polyatomic ion. Write the formula of for this lon and be sure to
include the ion charge.
d) Using the monatomic ions you listed above in (b), the polyatomic ion from (c), write the formulas for the
three ionic compounds these ions could form.

Answer 1

a) Barium has 2 valence electrons because it is in group 2 of the periodic table and all elements in this group have 2 valence electrons. Phosphorus has 5 valence electrons because it is in group 15 and all elements in this group have 5 valence electrons. Oxygen has 6 valence electrons because it is in group 16 and all elements in this group have 6 valence electrons.

b) Based on the number of valence electrons, the monatomic ions that each element may form are:

• Barium: Ba2+

• Phosphorus: P3-

• Oxygen: O2-

c) The polyatomic ion formed by phosphorus and oxygen is the phosphate ion, which has the formula PO4 3-.

d) Using the monatomic ions listed above and the phosphate ion, the formulas for the three ionic compounds that these ions could form are:

• Barium phosphate: Ba3(PO4)2

• Phosphorus oxide: P4O6

• Oxygen barium: O2Ba