Question

1. zinc phosphide, zn₃p₂, is often used as a rat poison. phosphorus has 5 valence electrons. how many valence electrons does each zinc atom lose?

o 1
o 2
o 3
o 4

1. lithium nitride has the chemical formula li₃n. rubidium is in the same chemical family as lithium. what is the formula of rubidium nitride?

o rbn
o rbn₃
o rb₃n
o rb₂n₃

Explanation:

Step1: Determine phosphorus' charge

Phosphorus has 5 valence electrons and wants to gain 3 electrons to achieve a stable - 8 - electron configuration. So, the charge of the phosphide ion ($P^{3 - }$). In $Zn_3P_2$, there are 2 phosphorus atoms, so the total negative charge from phosphorus is $2\times(- 3)=-6$.

Step2: Determine zinc's charge

In a neutral compound $Zn_3P_2$, the total positive charge from zinc must balance the total negative charge from phosphorus. Since the total negative charge is - 6 and there are 3 zinc atoms, the charge on each zinc atom is + 2. So each zinc atom loses 2 valence electrons.

Step3: Analyze the charge of rubidium

Lithium is in Group 1 of the periodic table and has a + 1 charge in compounds. Rubidium, being in the same group as lithium, also has a + 1 charge in compounds. Nitrogen has 5 valence electrons and gains 3 electrons to achieve a stable - 8 - electron configuration, so the nitride ion has a charge of $N^{3 - }$.

Step4: Determine the formula of rubidium nitride

To balance the charges, we need 3 rubidium ions ($Rb^+$) for every 1 nitride ion ($N^{3 - }$). So the formula of rubidium nitride is $Rb_3N$.

Answer:

1. 2
2. C. $Rb_3N$