IB Chemistry HL S2.1 The ionic model questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

Type
Multiple choiceWritten
Difficulty
EasyMediumHard

Question 1

Multiple choiceEasy1 mark

A calcium fluoride crystal has the empirical formula CaF₂. Which description of its ionic lattice is consistent with this formula?

Show answer and explanation

Answer: B. An ionic empirical formula gives the simplest whole-number ratio of ions in the lattice. In CaF₂, one Ca²⁺ balances the charge of two F⁻ ions, giving a ratio of 1:2.

A: reverses the subscripts, giving a ratio of 2:1.
C: assigns calcium a +1 charge, so the stated ratio is not charge-balanced.
D: uses equal numbers of ions, leaving the charges unbalanced.

Remember: ionic formulas give ratios of ions in a lattice, not discrete molecules.