Key idea
Isotopes
N = A − Z
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Their chemistry is very similar, while their masses and nuclear stability can differ.
Isotopes
The key idea
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Their chemistry is very similar, while their masses and nuclear stability can differ.
Why it matters
One element can therefore have several nuclear versions without changing its place in the periodic table.
A useful mental picture
Key idea
Isotopes
+
Guided example
Isotopes
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Their chemistry is very similar, while their masses and nuclear stability can differ.
Put it into practice
Isotopes
Choose a concrete case linked to Isotopes. Write down the known information, what you are trying to find, and the units. Then state the rule, model or trend you will use. If a calculation is involved, keep the units visible at every line; if it is conceptual, state what changes and what remains fixed.
Check your answer
A strong answer contains four things: the starting situation, the variable that changes, the direction or numerical result, and one check. The check can be a unit, an order of magnitude, a limiting case or a comparison with a familiar example.