Video Question #3 What do elements in the same period have in common?
a
they were all discovered around the same time
b
they all have the same number of energy shells
c
they all have similar properties
d
they all have the same number of valence electrons
b
they all have the same number of energy shells
The correct answer is b) they all have the same number of energy shells.
Elements in the same period of the periodic table share a common characteristic - they all have the same number of electron shells or energy levels. Periods in the periodic table are determined by the number of electron shells that an element's atoms have. As you move from left to right across a period, the number of shells increases by one.