Here's how to determine how much greater the mass of a bromine atom is compared to a helium atom:

1. Find the atomic masses:

* Bromine (Br): 79.904 atomic mass units (amu)

* Helium (He): 4.0026 atomic mass units (amu)

2. Calculate the ratio:

Divide the atomic mass of bromine by the atomic mass of helium:

79.904 amu / 4.0026 amu ≈ 19.96

Answer: A bromine atom is approximately 19.96 times greater in mass than a helium atom.