Question

inorganic nomenclature ~ naming inorganic compounds
every compound has its own chemical formula and its own name. the nomenclature (naming systems) for ionic and covalent compounds are different.
ionic compounds:
these consist of any positive ion (except h⁺) combined with any negative ion. (if h⁺ is the positive ion, the compound is an acid, as we will see later on page 6.)
the positive ion (cation) may be a metal ion (such as na⁺) or a polyatomic ion (such as nh₄⁺)
the negative ion (anion) may be a non - metal ion (such as cl⁻) or a polyatomic ion (such as so₄²⁻ or no₃⁻)
when writing formulas for ionic compounds, the net charge of the formula unit must be zero.
ex: ca⁺² and cl⁻¹
2 cl⁻¹ and 1 ca⁺² together have a net charge of zero
so the formula is cacl₂
case 1. ionic compounds: representative metal + non - metal
examples: kbr potassium bromide alcl₃ aluminum chloride li₃n lithium nitride
note 1: metal is always first (name unchanged), non - metal second (the ending of the non - metal is dropped, and the - ide ending is added).
note 2: the name does not indicate how many of each are in the formula unit..
exercise: write formulas for the following cations:
barium ion ___ aluminum ion _ potassium ion _ radium ion ___
exercise: write formulas for the following anions:
bromide ___ nitride _ iodide _ oxide _ sulfide ___
exercise: name the following:
naf ____________________
mgs ____________________
sri₂ ____________________
ca₃n₂ ____________________
k₂o ____________________
al₂o₃ ____________________
ba₃n₂ ____________________
na₃p ____________________
exercise: give formulas for the following compounds (refer to periodic table only).
cesium phosphide ________ calcium iodide ______ barium fluoride ________
magnesium nitride ________ aluminum bromide ______ sodium selenide ________

Explanation:

Step1: Recall metal - ion charges

Metals in Group 1 have a +1 charge, Group 2 have a +2 charge, and Group 13 have a +3 charge. Barium is in Group 2 so its ion is $Ba^{2 +}$, aluminum in Group 13 so its ion is $Al^{3+}$, potassium in Group 1 so its ion is $K^{+}$, radium in Group 2 so its ion is $Ra^{2+}$.

Step2: Recall non - metal ion charges

Non - metals in Group 15 have a - 3 charge, Group 16 have a - 2 charge, and Group 17 have a - 1 charge. Bromide ($Br^{-}$) from Group 17, nitride ($N^{3 -}$) from Group 15, iodide ($I^{-}$) from Group 17, oxide ($O^{2 -}$) from Group 16, sulfide ($S^{2 -}$) from Group 16.

Step3: Name ionic compounds

For $NaF$, sodium is the metal and fluorine is the non - metal, so it is sodium fluoride. For $MgS$, magnesium is the metal and sulfur is the non - metal, so it is magnesium sulfide. For $SrI_{2}$, strontium is the metal and iodine is the non - metal, so it is strontium iodide. For $Ca_{3}N_{2}$, calcium is the metal and nitrogen is the non - metal, so it is calcium nitride. For $K_{2}O$, potassium is the metal and oxygen is the non - metal, so it is potassium oxide. For $Al_{2}O_{3}$, aluminum is the metal and oxygen is the non - metal, so it is aluminum oxide. For $Ba_{3}N_{2}$, barium is the metal and nitrogen is the non - metal, so it is barium nitride. For $Na_{3}P$, sodium is the metal and phosphorus is the non - metal, so it is sodium phosphide.

Step4: Write formulas for compounds

Cesium is in Group 1 with a +1 charge and phosphorus in Group 15 with a - 3 charge, so cesium phosphide is $Cs_{3}P$. Calcium in Group 2 with a +2 charge and iodine in Group 17 with a - 1 charge, so calcium iodide is $CaI_{2}$. Barium in Group 2 with a +2 charge and fluorine in Group 17 with a - 1 charge, so barium fluoride is $BaF_{2}$. Magnesium in Group 2 with a +2 charge and nitrogen in Group 15 with a - 3 charge, so magnesium nitride is $Mg_{3}N_{2}$. Aluminum in Group 13 with a +3 charge and bromine in Group 17 with a - 1 charge, so aluminum bromide is $AlBr_{3}$. Sodium in Group 1 with a +1 charge and selenium in Group 16 with a - 2 charge, so sodium selenide is $Na_{2}Se$.

Answer:

barium ion: $Ba^{2+}$
aluminum ion: $Al^{3+}$
potassium ion: $K^{+}$
radium ion: $Ra^{2+}$
bromide: $Br^{-}$
nitride: $N^{3 -}$
iodide: $I^{-}$
oxide: $O^{2 -}$
sulfide: $S^{2 -}$
$NaF$: sodium fluoride
$MgS$: magnesium sulfide
$SrI_{2}$: strontium iodide
$Ca_{3}N_{2}$: calcium nitride
$K_{2}O$: potassium oxide
$Al_{2}O_{3}$: aluminum oxide
$Ba_{3}N_{2}$: barium nitride
$Na_{3}P$: sodium phosphide
cesium phosphide: $Cs_{3}P$
calcium iodide: $CaI_{2}$
barium fluoride: $BaF_{2}$
magnesium nitride: $Mg_{3}N_{2}$
aluminum bromide: $AlBr_{3}$
sodium selenide: $Na_{2}Se$