EasyChemistryHigh School (9–10)GeneralStructure of the Atom › Isotopes and IsobarsNumericalConceptualBoard Exam
Calcium-40 has Z = 20, and argon-40 has Z = 18…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Calcium-40 has , and argon-40 has .
- Find the protons, neutrons and electrons in a neutral atom of each.
- How many more neutrons does argon-40 have?
- Are they isotopes or isobars?
Need a reminder? The key ideaShow
Isotopes are atoms of the same element, with the same and a different . They have the same electrons, so the same chemical properties. Isobars are atoms of different elements with the same and a different . The mass of a molecule is the sum of the masses of its atoms.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Calcium-40. protons, neutrons, electrons.
Step 2. Argon-40. protons, neutrons, electrons.
Step 3. (b) more neutrons in argon-40.
Step 4. (c) Same mass number, different atomic numbers: isobars.
Answer: (a) and . (b) . (c) isobars.
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