Question

The atomic number of cesium (Cs) is 55. If an atom of cesium has 78 neutrons, what is the atomic mass of cesium?

Answer 1

The atomic number of cesium = 55

So number of electron in cesium = 55

While number of protons in cesium = 55

Atomic mass of cesium= number of protons + number of neutrons

Number of neutrons in cesium is given as 78

Atomic mass of cesium= number of protons + number of neutrons

Atomic mass of cesium=55 + 78

= 133

So, atomic weight of cesium is 133