Question

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wk. #2
directions - use your periodic table and the chart above. if given the name: write the formula,
if given the formula: write the name of the following covalent compounds.

a. diphosphorus pentoxide

b. boron trichloride

c. dinitrogen tetroxide

d. n₂o

e. pf₅

f. cbr₄

directions – write the formulas of the ionic compounds produced from the listed ions.

	no₃¹⁻	s²⁻	aso₄³⁻	cn⁻
fr⁺
ga³⁺
nh₄⁺

Explanation:

Part 1: Covalent Compounds

a. Diphosphorus pentoxide

Step1: Identify elements and prefixes. "Di-" means 2 for P, "penta-" means 5 for O.
Formula: $P_2O_5$

b. Boron trichloride

Step1: "Tri-" means 3 for Cl, B has 1 (no prefix).
Formula: $BCl_3$

c. Dinitrogen tetroxide

Step1: "Di-" (2 N), "tetra-" (4 O).
Formula: $N_2O_4$

d. $N_2O$

Step1: 2 N (dinitrogen), 1 O (monoxide, "mono-" often omitted for first element).
Name: Dinitrogen monoxide (or nitrous oxide)

e. $PF_5$

Step1: P (phosphorus), F (fluorine) with "penta-".
Name: Phosphorus pentafluoride

f. $CBr_4$

Step1: C (carbon), Br (bromine) with "tetra-".
Name: Carbon tetrabromide

Part 2: Ionic Compounds (Using Criss-Cross Method)

For $Ba^{2+}$:

• With $NO_3^{1-}$: Charge ratio 2:1, formula $Ba(NO_3)_2$
• With $S^{2-}$: Charge ratio 2:2 (simplify to 1:1), formula $BaS$
• With $AsO_4^{3-}$: Charge ratio 2:3, formula $Ba_3(AsO_4)_2$
• With $CN^-$: Charge ratio 2:1, formula $Ba(CN)_2$

For $Fr^+$:

• With $NO_3^{1-}$: Charge ratio 1:1, formula $FrNO_3$
• With $S^{2-}$: Charge ratio 1:2, formula $Fr_2S$
• With $AsO_4^{3-}$: Charge ratio 1:3, formula $Fr_3AsO_4$
• With $CN^-$: Charge ratio 1:1, formula $FrCN$

For $Ga^{3+}$:

• With $NO_3^{1-}$: Charge ratio 3:1, formula $Ga(NO_3)_3$
• With $S^{2-}$: Charge ratio 3:2, formula $Ga_2S_3$
• With $AsO_4^{3-}$: Charge ratio 3:3 (simplify to 1:1), formula $GaAsO_4$
• With $CN^-$: Charge ratio 3:1, formula $Ga(CN)_3$

For $NH_4^+$:

• With $NO_3^{1-}$: Charge ratio 1:1, formula $NH_4NO_3$
• With $S^{2-}$: Charge ratio 1:2, formula $(NH_4)_2S$
• With $AsO_4^{3-}$: Charge ratio 1:3, formula $(NH_4)_3AsO_4$
• With $CN^-$: Charge ratio 1:1, formula $NH_4CN$

Answer:

Part 1 (Covalent Compounds):

a. $P_2O_5$
b. $BCl_3$
c. $N_2O_4$
d. Dinitrogen monoxide (nitrous oxide)
e. Phosphorus pentafluoride
f. Carbon tetrabromide

Part 2 (Ionic Compounds Table):

	$NO_3^{1-}$	$S^{2-}$	$AsO_4^{3-}$	$CN^-$
$Fr^+$	$FrNO_3$	$Fr_2S$	$Fr_3AsO_4$	$FrCN$
$Ga^{3+}$	$Ga(NO_3)_3$	$Ga_2S_3$	$GaAsO_4$	$Ga(CN)_3$
$NH_4^+$	$NH_4NO_3$	$(NH_4)_2S$	$(NH_4)_3AsO_4$	$NH_4CN$