Question

atomic mass
the atomic mass of elements increases moving ? each group and ? across each period.
answer bank
up
down
left
right

Explanation:

In the periodic table, the atomic mass of elements increases as we move down each group (because more electron - shells and more protons, neutrons are added). Also, the atomic mass increases as we move right across each period (due to an increase in the number of protons and neutrons).

Answer:

DOWN, RIGHT