How to Calculate Protons Neutrons and Electrons Worksheet

Subatomic Particle Calculator

Determine Protons, Neutrons, and Electrons instantly

The number of protons (found on Periodic Table)

Total sum of protons and neutrons

Use 0 for neutral atoms, +1, -2, etc., for ions

Calculation Results

–

Protons

–

Neutrons

–

Electrons

function calculateParticles() { var z = parseInt(document.getElementById('atomicNumber').value); var a = parseInt(document.getElementById('massNumber').value); var c = parseInt(document.getElementById('netCharge').value); if (isNaN(z) || isNaN(a)) { alert("Please enter valid numbers for Atomic Number and Mass Number."); return; } if (z > a) { alert("Mass Number (A) must be greater than or equal to Atomic Number (Z)."); return; } if (isNaN(c)) { c = 0; } var protons = z; var neutrons = a – z; var electrons = z – c; document.getElementById('resProtons').innerHTML = protons; document.getElementById('resNeutrons').innerHTML = neutrons; document.getElementById('resElectrons').innerHTML = electrons; var summary = "Summary: This atom/ion has an atomic number of " + z + ", meaning it is element #" + z + ". "; summary += "Because the mass number is " + a + ", we subtract the protons to find " + neutrons + " neutrons. "; if (c === 0) { summary += "As a neutral atom (charge 0), the number of electrons equals the number of protons (" + electrons + ")."; } else if (c > 0) { summary += "With a positive charge of +" + c + ", it has lost " + c + " electron(s), resulting in " + electrons + " total electrons."; } else { summary += "With a negative charge of " + c + ", it has gained " + Math.abs(c) + " electron(s), resulting in " + electrons + " total electrons."; } document.getElementById('particleSummary').innerHTML = summary; document.getElementById('particleResult').style.display = 'block'; }

How to Calculate Protons, Neutrons, and Electrons: A Step-by-Step Guide

Understanding the internal structure of an atom is fundamental to chemistry. Every atom is composed of three primary subatomic particles: protons, neutrons, and electrons. Whether you are working on a chemistry worksheet or studying for an exam, mastering these calculations is essential.

The Three Golden Rules

1. Protons: The number of protons is always equal to the Atomic Number (Z). This number defines the identity of the element.
2. Neutrons: To find neutrons, subtract the Atomic Number from the Mass Number (A). Formula: N = A - Z.
3. Electrons: In a neutral atom, electrons equal protons. If the atom is an ion, subtract the Charge (C) from the Atomic Number. Formula: E = Z - C.

Key Definitions for Your Worksheet

Before using the calculator above, ensure you understand these terms:

• Atomic Number (Z): Found on the periodic table above the element symbol. It tells you exactly how many protons are in the nucleus.
• Mass Number (A): The total count of protons and neutrons. Note: This is usually a whole number provided in the problem (e.g., Carbon-14), not the decimal atomic weight found on the periodic table.
• Ions: Atoms that have gained or lost electrons, giving them a net positive or negative charge.

Example Calculations

Element/Ion	Atomic # (Z)	Mass # (A)	Charge	P / N / E
Carbon-12	6	12	0	6 / 6 / 6
Sodium Ion (Na+)	11	23	+1	11 / 12 / 10
Chlorine-37	17	37	0	17 / 20 / 17

Common Mistakes to Avoid

Many students confuse the Atomic Mass (the decimal on the periodic table) with the Mass Number. Always use the specific mass number given for the isotope you are calculating. Also, remember that a positive charge means you subtract electrons, while a negative charge means you add them.

© Subatomic Particle Worksheet Tool – Designed for Chemistry Students