The number of protons and neutrons combined in an atom is called the mass number.
55.8 grams Would be the answer
1st level = s
<span>2nd level = s,p </span>
<span>3rd level = s,p,d </span>
<span>4th level = s,p,d,f</span>
Answer:
An atom gets larger as the number of electronic shells increase; therefore the radius of atoms increases as you go down a certain group in the periodic table of elements. In general, the size of an atom will decrease as you move from left to the right of a certain period.
Explanation:
