Genetic relationships among inorganic compounds
“Genetic relationship” in chemistry means that substances of different classes can be converted into one another through suitable reactions. It describes chemical origin and transformation, not biological inheritance.
Learning goals
- Connect elements, oxides, bases, acids, and salts in reaction chains.
- Select reagents and conditions for each conversion.
- Write and balance equations that support a proposed route.
- Recognize when solubility, activity, gas formation, or heating is required.
Two central pathways
Typical metal pathway: $Ca\rightarrow CaO\rightarrow Ca(OH)_2\rightarrow CaCl_2$. Typical nonmetal pathway: $S\rightarrow SO_2\rightarrow H_2SO_3\rightarrow Na_2SO_3$. These are models; not every oxide reacts with water, so actual chemistry must be checked.
Building a valid route
- Name the starting and target classes.
- Choose a known reaction pattern.
- Check special conditions: oxygen, water, acid, base, heat, solubility, or activity.
- Write correct formulas and balance coefficients.
- Confirm a driving force such as precipitate, gas, water, or oxidation.
| Conversion | Possible method | Example |
|---|---|---|
| element → oxide | reaction with oxygen | $2Ca+O_2\rightarrow2CaO$ |
| basic oxide → base | water, when oxide is suitable | $CaO+H_2O\rightarrow Ca(OH)_2$ |
| base → salt | neutralization | $Ca(OH)_2+2HCl\rightarrow CaCl_2+2H_2O$ |
| salt → insoluble base | precipitation | $CuSO_4+2NaOH\rightarrow Cu(OH)_2\downarrow+Na_2SO_4$ |
| insoluble base → oxide | heating | $Cu(OH)_2\xrightarrow{\Delta}CuO+H_2O$ |