There are 7 periods. These describe number of shells.
Usually at the top ... and classically written in Roman numerals.Yes, there are numbers at the top of a periodic table, although they are for the groups/families on the periodic table. Usually the period numbers are found to the left of the periodic table.
The period to which the element belongs
Copper is located in period 4 of the periodic table.
Helium is in the first period of the periodic table.
No. Xenon is not the first period of the periodic table. It is placed in the 5th period of periodic table.
Argon is in the third period of the modern periodic table.
Oxygen is in Period 2 , Group 16 ( VI A) of periodic table
The atomic number of sodium is 11. Other numbers are 3rd period and column 1.
Caesium is a Period 6 element.
No , Iodine is placed in period-5 of the periodic table.
Sulfur (S, element number 16) is on the third period of the periodic table.
A period on the periodic table is a row.This is the horizontal section of the periodic table.