Name each of the following ionic compounds containing a polyatomic ion. Spell out the full name of the compound.
Ba (OH)2
NH4BR
NaClO4
FEPO4
CoCrO4
KClO4
The correct answer and explanation is :
Here are the correct names for the given ionic compounds:
- Ba(OH)₂ → Barium hydroxide
- NH₄Br → Ammonium bromide
- NaClO₄ → Sodium perchlorate
- FePO₄ → Iron(III) phosphate
- CoCrO₄ → Cobalt(II) chromate
- KClO₄ → Potassium perchlorate
Explanation:
When naming ionic compounds that contain polyatomic ions, follow these key rules:
- Identify the cation (positive ion): The cation is usually a metal or the ammonium ion (NH₄⁺).
- Determine the polyatomic ion (negative ion): Polyatomic ions are groups of atoms that carry a charge and act as a single unit.
- Use the correct naming conventions:
- Metals in Groups 1 and 2, along with aluminum, zinc, and silver, have fixed charges and do not require Roman numerals.
- Transition metals can have variable charges, so Roman numerals indicate the metal’s oxidation state.
- Polyatomic ions have specific names that must be memorized.
Now, let’s break down the compounds:
- Barium hydroxide (Ba(OH)₂)
- Barium (Ba²⁺) is from Group 2, so it has a fixed charge (+2).
- Hydroxide (OH⁻) is a known polyatomic ion.
- Ammonium bromide (NH₄Br)
- Ammonium (NH₄⁺) is a polyatomic cation.
- Bromide (Br⁻) is a monatomic anion.
- Sodium perchlorate (NaClO₄)
- Sodium (Na⁺) is from Group 1, so it has a fixed charge (+1).
- Perchlorate (ClO₄⁻) is a polyatomic ion.
- Iron(III) phosphate (FePO₄)
- Phosphate (PO₄³⁻) has a charge of -3.
- Since iron must balance the charge, it has a +3 charge (Fe³⁺), hence “Iron(III)”.
- Cobalt(II) chromate (CoCrO₄)
- Chromate (CrO₄²⁻) has a charge of -2.
- Cobalt must balance the charge with +2, so it is “Cobalt(II)”.
- Potassium perchlorate (KClO₄)
- Potassium (K⁺) is from Group 1, so it has a fixed charge (+1).
- Perchlorate (ClO₄⁻) is a polyatomic ion.
These rules help ensure accurate naming of ionic compounds.