A formula unit is an empirical formula.
What you write for an ionic compound is called the formula unit, but the formula unit is almost always the same as the empirical formula. The answer to your question could not be the molecular formula because an ionic compound is not a molecule.
A formula unit
That's not a valid empirical formula. Assuming you meant aluminum chloride and just didn't know the real formula, it's AlCl3 with four atoms per formula unit.
The gram molecular mass of the molecule must be measured by some independent method such as freezing point depression or boiling point elevation. Then the factor by which to multiply all of the subscripts in the empirical formula to get the molecular formula is the closest integer to the ratio of gram molecular mass to the gram molecular mass of a single unit of the empirical formula.
Formula: Be(NO2)2
A formula unit is an empirical formula.
A formula unit includes the correct number of each kind of atoms present in a molecule of a covalently bonded compound, but an empirical formula does not necessarily do so. An empirical formula is reliable with respect to the ratios between each kind of atom, but the molecule may contain any positive integral number of empirical formulas, including one.
In this instance, the empirical formula is the same as the formula unit: NaNO3
An empirical formula refers to the chemical formula that indicates the simplest ratio of atoms in a compound. Two different compounds may have the same empirical formula.
This is the chemical formula (empirical formula) or the formula unit of this compound.
an empirical formula For an ionic compound, the empirical formula is called a formula unit.
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What you write for an ionic compound is called the formula unit, but the formula unit is almost always the same as the empirical formula. The answer to your question could not be the molecular formula because an ionic compound is not a molecule.
For sodium oxide, the empirical formula is the same as the formula unit, Na2O. (If any formula unit or molecular formula contains an atomic symbol with no following subscript, the empirical and actual formulas will be the same.)
A formula unit
The formula unit for an ionic compound is similar to an empirical formula in that both give the simplest whole-number ratio of atoms of each element in a compound.
Emperical formula give the smallest whole number ratio of atoms in a compound