Atom Calculator

How to use the atom calculator

What this calculator does

This calculator converts three nuclear-notation inputs into particle counts for one isotope or ion. Atomic number identifies the element and proton count, mass number determines neutrons, and signed ion charge determines electrons. The results are exact arithmetic identities for the supplied integers; they do not predict isotope stability, radioactive half-life, electron configuration, or the naturally averaged atomic weight on a periodic table. For evaluated element identities and atomic data, see the NIST Periodic Table of the Elements.

When to use it

Use it to translate isotope notation into subatomic-particle counts, check chemistry exercises, distinguish a neutral atom from an ion, or compare isotopes of one element. Isotopes retain the same proton count while changing neutron count; ions retain the same nucleus while changing electron count.

How to calculate

1. The calculator opens with chlorine-37 at charge – 1, so meaningful results and a validated example workbook are immediately available.
2. Replace Atomic number (Z) with an integer from 1 to 118.
3. Enter a whole Mass number (A) at least as large as Z.
4. Enter Ion charge (z) as positive, negative, or zero.
5. Read the notation, result cards, and particle table; then use Download Excel for the current state.
6. Reset clears the sample and results. Export stays disabled until all three required fields are valid again.

Input guide

Atomic number (Z) is a required plain integer from 1 through 118. It equals proton count and uniquely determines the element. The sample value 17 means chlorine. Raising Z changes the element and normally changes electrons too. Do not enter an element symbol, decimal, or average atomic weight.

Mass number (A) is a required positive whole number equal to protons plus neutrons. The sample value 37 means 37 nucleons. A must be at least Z, because a negative neutron count is impossible. Increasing A while holding Z fixed adds neutrons and describes another isotope. Do not use the decimal atomic weight printed on a periodic table; the CIAAW standard atomic-weight table explains those averaged values.

Ion charge (z) is a required signed integer. Enter – 1 for one extra electron, +2 for two missing electrons, or 0 for a neutral atom. The convention is z = protons – electrons, so e = Z – z. A charge greater than Z is rejected because it would imply a negative electron count. A common mistake is reversing the sign: negative charge increases electrons.

Output guide

Isotope / ion notation combines A, Z, the element symbol, and charge. Protons equals Z, Neutrons equals A – Z, and Electrons equals Z – z. The Element, Nucleons, and Net charge pills repeat the key identity. The table's Electrical charge, Location, and Formula columns explain each particle. A zero neutron count can be arithmetically valid when A = Z, but existence and stability are separate nuclear-physics questions.

Worked example

For Z = 17, A = 37, and z = – 1: p = 17; n = 37 – 17 = 20; and e = 17 – ( – 1) = 18. Atomic number 17 identifies chlorine, so the calculator displays ³⁷₁₇Cl⁻. The same 17, 20, and 18 values appear in the result cards, table, accessible summary, and workbook.