Build an atom
Put together atoms, isotopes and ions from protons, neutrons and electrons. Solve the tasks or build freely.
0 of 14 solved
Task 1/14: Build a neutral hydrogen atom (¹H).
- Element
- No element without protons
- Mass number
- 0
- Charge
- 0
- Notation
- ⁰?
What you need to know for this exercise
An atom consists of a tiny nucleus surrounded by electron shells. The protons and the neutrons sit in the nucleus. Protons carry a positive charge, neutrons are uncharged. The electrons move in these shells and carry a negative charge.
The number of protons determines the element. It is called the atomic number. An atom with six protons is always carbon, no matter how many neutrons it has. The mass number is the sum of protons and neutrons, because electrons are almost massless in comparison.
Atoms of the same element with different numbers of neutrons are called isotopes. Carbon-12 and carbon-14 both have six protons, but six and eight neutrons respectively. Some isotopes are stable, others decay over time.
A neutral atom has as many electrons as protons. If it gains or loses electrons, it becomes an ion. With too few electrons it is a positive cation, with too many a negative anion. The charge is the number of protons minus the number of electrons. In the notation ²³Na⁺ the mass number is at the top left, the symbol in the middle and the charge at the top right.
The electrons fill the shells from the inside out. The first shell holds two electrons, and in this simple rule the second and the third hold eight each. From the 19th electron on, the fourth shell begins, and the simple 2-8-8-2 picture only holds up to calcium (Z = 20). Build atoms and ions in the exercise and check your result.