Atomic number defines the element
Changing neutron count creates an isotope. Changing electron count creates an ion. But changing proton count changes the element itself.
Start with the idea
Changing neutron count creates an isotope. Changing electron count creates an ion. But changing proton count changes the element itself.
A concrete example
11 protons means sodium. 12 protons means magnesium. This remains true regardless of isotope or electric charge.
Mendeleev’s tip
Do not start with a formula. Identify what changes, what stays constant and which quantity you are trying to explain or calculate.
Go one step deeper
Carbon-12 and carbon-14 both have 6 protons. Their neutron counts differ, but both remain carbon.
A trend or model is not an exceptionless law. Always check the quantity’s definition and the conditions being compared.
Check your understanding
Can you explain the phenomenon in your own words before looking at an equation?