Answer: PCl₃O
Explanation:
1) The chemical formula tells the composition of a compound in terms of the ratio of number of atoms of each element that consitutes such compound.
2) You use the chemical symbol for each kind of atom (element) and subscripts to the right of each symbol to tell the number of atoms of each element.
3) For example, O₂ means two atoms of oxygen. Al₂O₃ means two atoms of aluminum and 3 atoms of oxygen.
4) Therefore, PCl₃O means a ratio 1 : 3 : 1 for phosphorus, chlorine, and oxygen.
Hence, PCl₃O is the chemical formula of your compound.
The molecules or atoms that are formed by gain or loss of one or more valence electrons are said to be ions.
When atom loss one or more valence electrons, results in formation of cation whereas when atom gain one or more valence electrons, then formation of anion occurs. Cations carry positive charge and anions carry negative charge.
In general, cations are smaller than the neutral atoms from which they are formed and anions are larger than the neutral atoms.
As cations are smaller than the related neutral atoms because the valence electrons are lost which are farthest away from the nucleus. After that, taking more electrons distant from the cation results in reduction of radius of the ion.
Thus, aluminium cation consist of few electrons which results in fewer occupied energy levels by the electrons further results in reduction of radius i.e. smaller size.
Hence, given statement is true i.e. aluminium atom is larger than the aluminium cation as cation has fewer occupied energy levels.