Atomic Structure: Make Elements from Particles
Understand that the number of protons (the atomic number) decides the element, that protons plus neutrons give the mass number, and that an atom becomes an ion only by gaining or losing electrons.
Before you try
What if you added one more proton to a carbon atom? Would it still be carbon?
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What happened?
Move a control to see what changes and why.
Electrons are drawn in neat shells. Real electrons follow no fixed path: they are better pictured as a cloud of likely positions.
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Try these ideas
- Build carbon-12, then add two neutrons to make carbon-14.
- Start from neutral sodium and remove one electron to make Na⁺.
- Press Build this and match the target element, isotope and charge.
Why it works
Every atom has a tiny nucleus of protons and neutrons, surrounded by electrons. The proton count, called the atomic number Z, is the atom’s identity: six protons is always carbon, seven is always nitrogen. Change the neutron count and you get a different isotope of the same element, such as carbon-12 and carbon-14. Change the electron count and the charges no longer balance, so you get an ion.
In this simulator you set each particle count and watch the nucleus, the electron shells and the element symbol update. Electrons fill shells in the familiar 2, 8, 8, 2 pattern used in school chemistry, and a rough rule flags nuclei whose neutron count is far from the usual, marking them as likely radioactive. Real atoms are described by orbitals, and stability depends on more than a simple count.
Check your understanding
Question 1 of 4
What decides which element an atom is?
An atom has 11 protons, 12 neutrons and 10 electrons. What is it?
Carbon-12 and carbon-14 differ in what way?
How does a neutral atom become a positive ion?
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
What will you discover next?
Try Balancing Chemical Equations: Match Every Atom next.
For parents & teachers
- Find sodium and chlorine on a periodic table and compare their proton counts.
- Ask why carbon-14 is useful for dating ancient wood and bone.
- Discuss how table salt forms when sodium gives an electron to chlorine.