Question

true or false question
true or false: atomic mass does not always increase from left to right in the periodic table.

○ true

○ false

Explanation:

In the periodic table, while atomic number (number of protons) always increases from left to right across a period, atomic mass (which depends on protons and neutrons) does not always increase. For example, argon (Ar, atomic mass ~39.95) comes before potassium (K, atomic mass ~39.10), and cobalt (Co, atomic mass ~58.93) comes before nickel (Ni, atomic mass ~58.69). So atomic mass does not always increase from left to right.

Answer:

True