1. Co₂O₃
2. V₂S₅
3. LiI (The third letter is I as in Iodine)
4. Pb₃N₂
5. AgBr
6. TiSe
7. CaF₂
8. GaCl₃
9. NaH
10. Mn₃As₇
Explanation:
Writing the formula of an ionic compound, you will need to know the charges of the atoms involved. We have the criss-cross method, which makes things easier.
1. Cobalt (III) oxide
Cobalt here has a charge of 3+ (the III tells the oxidation state of the metal)
Oxygen has a charge of 2-
So write that down:
Co³⁺ O²⁻
Next you will cross the charges and write them as subscript of the other.
Co₂O₃
2. Vanadium (V) sulfide
Vanadium here has a charge of 5+
Sulfur has a charge of 2-
Write it down:
V⁵⁺ S²⁻
V₂S₅
3. Lithium iodide
Lithium has a charge of 1+
Iodine has a charge of 1-
Li⁺ I⁻ (If the charge is 1 we do not need to write it down)
Li₁I₁
LiI
4. Lead (II) nitride
Lead has a charge of 2+
Nitrogen has a charge of 3-
*** The symbol of Lead is Pb, and it comes from the Latin word Plumbum***
Pb ²⁺ N³⁻
Pb₃N₂
5. Silver bromide
Silver has a charge of 1+
Bromine has a charge of 1-
***Silver also has multiple oxidation states, but since there is no Roman numeral in between, this means that the oxidation state is 1. Also the symbol is based on the Latin name of sliver Argentum, the symbol is Ag)
Ag¹⁺ Br¹⁻
AgBr
6. Titanium (II) Selenide
Titanium has a charge of 2+
Selenium has a charge of 2-
Ti²⁺ Se²⁻
Ti₂Se₂
*** When we write chemical formulas always write them in the lowest ratio***
Ti₂Se₂ = TiSe
7. Calcium fluoride
Calcium has a charge of 2+
Flourine has a charge of 1-
Ca²⁺ F¹⁻
Ca₁F₂
CaF₂
8. Gallium choride
Gallium has a charge of 4+
Chlorine has a charge of 1-
Ga3⁺ Cl⁻
GaCl₃
9. Sodium hydride
Sodium has a charge of 1+
Hydrogen technically has a charge of 1+ as well but you see, Hydrogen actually needs to fill in its outer shell of 2 only. So it will need 1 electron to fill it. So in this case, it will accept an electron of 1
Na¹⁺ H¹⁻
NaH
10. Manganese (VII) arsenide
Manganese has a charge of 7+
Arsenic has a charge of 3-
Mn⁷⁺ As³⁻
Mn₃As₇
