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

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

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.