C14
Mendeleev example
Carbon-14: a nuclear clock
Carbon-14 decay can be used to estimate the age of once-living material within its useful range.
Mendeleev
Start with the particle story: which protons, electrons or nuclei are changing? Then connect that story to the property you observe.
1
Identify the particles or structure involved.
2
Predict the direction of the effect.
3
Check the explanation against the periodic table or a measured property.