Question

fill in the systematic names of the following chemical compounds.
note: for compounds containing hydrogen, you may give the common name instead.

molecular formula	name of compound
$n_2f_4$	$\square$
$p_3s_4$	$\square$
$nf_3$	$\square$
$h_2o$	$\square$

Explanation:

To determine the systematic names of the given molecular compounds, we use the rules for naming molecular (covalent) compounds: prefixes are used to indicate the number of each atom (1: mono, 2: di, 3: tri, 4: tetra, 5: penta, 6: hexa, 7: hepta, 8: octa, 9: nona, 10: deca). The first element is named with a prefix (except if there's only one atom, then "mono" is omitted), and the second element ends with "-ide" and also has a prefix.

1. For $\boldsymbol{P_4S_7}$

• First element: $P$ (phosphorus). Number of $P$ atoms: 4 → "tetra".
• Second element: $S$ (sulfur). Number of $S$ atoms: 7 → "hepta", and end with "-ide" → "sulfide".
• Name: tetraphosphorus heptasulfide

2. For $\boldsymbol{N_2F_4}$

• First element: $N$ (nitrogen). Number of $N$ atoms: 2 → "di".
• Second element: $F$ (fluorine). Number of $F$ atoms: 4 → "tetra", and end with "-ide" → "fluoride".
• Name: dinitrogen tetrafluoride

3. For $\boldsymbol{P_3S_4}$

• First element: $P$ (phosphorus). Number of $P$ atoms: 3 → "tri".
• Second element: $S$ (sulfur). Number of $S$ atoms: 4 → "tetra", and end with "-ide" → "sulfide".
• Name: triphosphorus tetrasulfide

4. For $\boldsymbol{NF_3}$

• First element: $N$ (nitrogen). Only 1 $N$ atom → no prefix (or "mono" is omitted).
• Second element: $F$ (fluorine). Number of $F$ atoms: 3 → "tri", and end with "-ide" → "fluoride".
• Name: nitrogen trifluoride

5. For $\boldsymbol{H_2O}$ (common name is water, but systematic name follows covalent rules)

• First element: $H$ (hydrogen). Number of $H$ atoms: 2 → "di".
• Second element: $O$ (oxygen). Number of $O$ atoms: 1 → "mono" (but "mono" is often omitted for oxygen in common names, but systematic name: "dihydrogen monoxide" (though "water" is more common)).

Final Table (with systematic names):

Molecular Formula	Name of Compound
$N_2F_4$	Dinitrogen tetrafluoride
$P_3S_4$	Triphosphorus tetrasulfide
$NF_3$	Nitrogen trifluoride
$H_2O$	Dihydrogen monoxide (or Water)

(Note: For $H_2O$, "water" is the common name, while "dihydrogen monoxide" is the systematic covalent name, though it’s rarely used in practice.)

Answer:

To determine the systematic names of the given molecular compounds, we use the rules for naming molecular (covalent) compounds: prefixes are used to indicate the number of each atom (1: mono, 2: di, 3: tri, 4: tetra, 5: penta, 6: hexa, 7: hepta, 8: octa, 9: nona, 10: deca). The first element is named with a prefix (except if there's only one atom, then "mono" is omitted), and the second element ends with "-ide" and also has a prefix.

1. For $\boldsymbol{P_4S_7}$

• First element: $P$ (phosphorus). Number of $P$ atoms: 4 → "tetra".
• Second element: $S$ (sulfur). Number of $S$ atoms: 7 → "hepta", and end with "-ide" → "sulfide".
• Name: tetraphosphorus heptasulfide

2. For $\boldsymbol{N_2F_4}$

• First element: $N$ (nitrogen). Number of $N$ atoms: 2 → "di".
• Second element: $F$ (fluorine). Number of $F$ atoms: 4 → "tetra", and end with "-ide" → "fluoride".
• Name: dinitrogen tetrafluoride

3. For $\boldsymbol{P_3S_4}$

• First element: $P$ (phosphorus). Number of $P$ atoms: 3 → "tri".
• Second element: $S$ (sulfur). Number of $S$ atoms: 4 → "tetra", and end with "-ide" → "sulfide".
• Name: triphosphorus tetrasulfide

4. For $\boldsymbol{NF_3}$

• First element: $N$ (nitrogen). Only 1 $N$ atom → no prefix (or "mono" is omitted).
• Second element: $F$ (fluorine). Number of $F$ atoms: 3 → "tri", and end with "-ide" → "fluoride".
• Name: nitrogen trifluoride

5. For $\boldsymbol{H_2O}$ (common name is water, but systematic name follows covalent rules)

• First element: $H$ (hydrogen). Number of $H$ atoms: 2 → "di".
• Second element: $O$ (oxygen). Number of $O$ atoms: 1 → "mono" (but "mono" is often omitted for oxygen in common names, but systematic name: "dihydrogen monoxide" (though "water" is more common)).

Final Table (with systematic names):

Molecular Formula	Name of Compound
$N_2F_4$	Dinitrogen tetrafluoride
$P_3S_4$	Triphosphorus tetrasulfide
$NF_3$	Nitrogen trifluoride
$H_2O$	Dihydrogen monoxide (or Water)

(Note: For $H_2O$, "water" is the common name, while "dihydrogen monoxide" is the systematic covalent name, though it’s rarely used in practice.)