1. What is Atomic Mass Number?

The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It determines the isotope of an element.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( A \) — Mass number (dimensionless)
• \( p \) — Number of protons (atomic number)
• \( n \) — Number of neutrons

Explanation: The mass number is simply the sum of protons and neutrons in the nucleus of an atom.

3. Importance of Mass Number

Details: The mass number is fundamental in chemistry and physics as it identifies isotopes of an element and is used in nuclear equations and calculations of atomic mass.

4. Using the Calculator

Tips: Enter the number of protons (must be ≥1) and neutrons (must be ≥0). The calculator will sum these values to give the mass number.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between mass number and atomic mass?
A: Mass number is the count of nucleons (integer), while atomic mass is the weighted average mass of isotopes (usually a decimal).

Q2: Can mass number be less than atomic number?
A: No, mass number must be ≥ atomic number (proton count) since neutron count can't be negative.

Q3: How does mass number relate to isotopes?
A: Isotopes of an element have the same proton count but different neutron counts (different mass numbers).

Q4: Why isn't electron mass included?
A: Electron mass is negligible compared to nucleons (about 1/1836th of a proton's mass).

Q5: What's the typical range for mass numbers?
A: From 1 (hydrogen-1) to about 300 for superheavy elements, though most stable isotopes are below 210.