Type an element or an ion, such as Na, Fe2+ or Cl-. Free, no sign-up, and it runs in your browser.
The drawing updates as you change anything.
A Bohr model draws an atom as a nucleus with electrons on circular shells. Oxygen has atomic number 8, so eight protons and, in a neutral atom, eight electrons: two in the first shell and six in the second. Those six in the outer shell are its valence electrons, the ones involved in bonding.
It is a simplification. Electrons do not really circle the nucleus like planets, but the model is still a clear way to see how many electrons an atom has and how they are shared out between shells.
Simple rules for filling shells break down after calcium, so neutral atoms here use their measured ground-state configuration. Iron is 2, 8, 14, 2, rather than the pattern you might expect.
Ions are worked out the way they actually form. Positive ions lose electrons from the highest shell first, so Fe²⁺ empties its fourth shell before touching the third. Negative ions gain electrons in the next free places, so Cl⁻ fills its third shell to eight.
Yes. It is free, with no account and no limit, and it runs in your browser.
It starts from the element’s main or longest-lived isotope. Change the mass number to draw another one, and the neutron count follows.
Yes, all 118, along with a range of positive and negative ions for each.