Chemistry, atoms, ions, bonds / principles and exploration
Ionic compound ratios — principles and investigation
The chemical formula of an ionic substance indicates the number ratio in which the charges of positive and negative ions cancel out as a whole. Change the type and number of ions to find a combination that results in a total charge of 0. In the process of matching the charges and reducing them to the minimum integer ratio, the subscripts of the chemical formula are determined.
How does it work?
If you divide the number ratio where the charge becomes 0 by the greatest common divisor, you get the minimum integer ratio chemical formula.
Positive charge × number − negative charge size × number = 0
Try this investigation
- Change the number of positive and negative ions and check the total charge. First check whether the charge is 0, and then reduce the number ratio to the smallest.
- Execute and record the 1:1 conditions for MgO and 2:3 conditions for Al₂O₃, respectively.
- Check whether MgO's 2:2 and 1:1 are the same minimum ratio, and compare it with MgCl₂'s 1:2.
Interpreting your results
If the charges of 2 Mg²⁺ and 2 O²⁻ are 0, what is the chemical formula?
Chemical formulas use the minimum whole number ratio. If you reduce 2:2 to 1:1, you get MgO.
Assumptions and limitations
It is a charge coefficient model that only deals with Na⁺·Mg²⁺·Al³⁺ and Cl⁻·O²⁻. The pictures represent numbers, not actual crystal lattices or individual molecular shapes. Binding energy and crystal stability are not calculated.