The atomic mass of helium is significantly greater than its atomic number.
Understanding Atomic Number and Mass
Atomic Number
- The atomic number represents the number of protons in an atom's nucleus.
- For helium, the atomic number is 2, meaning it has two protons.
Atomic Mass (Mass Number)
- The atomic mass (or mass number) is the total number of protons and neutrons in an atom's nucleus.
- Helium has two protons and, as mentioned in the provided reference, also contains two neutrons.
- Therefore, the mass number of a typical helium atom is 2 + 2 = 4.
Comparison
| Feature | Helium |
|---|---|
| Atomic Number | 2 |
| Mass Number | 4 |
As shown in the table, the atomic mass of helium is twice the atomic number (4 compared to 2).
Key Takeaway
The atomic mass (mass number) of helium is a larger value than the atomic number. The atomic number is determined solely by the number of protons, while the mass number takes into account both protons and neutrons. The atomic mass is a count of total nucleons (protons + neutrons), and it directly reflects the weight of the atom's nucleus.
