Question

1. when you select an atom, it will be sitting on the balance which shows you the mass. click on h. note the mass number. click on he. note the mass number. describe the change in the mass number of the atoms as you go from left to right in period 1. the mass number stays the same as you go from left to right in a period 1. the mass number decreases as you go from left to right in a period 1. the mass number increases as you go from left to right in period 1.

Explanation:

Hydrogen (\(H\)) has a mass number of \(1\). Helium (\(He\)) has a mass number of \(4\). As we move from left (\(H\)) to right (\(He\)) in period \(1\) of the periodic table, the mass number increases.

Answer:

The mass number increases as you go from left to right in period 1.