How many elements do we find in the third period of the period table?
Third period has 8 elements. They have 3 electron shells.
What period on the periodic table of elements contains radioactive elements and what are they called?
The first period in which you'll find 18 elementS is the fourth (4th) period: going from 19-K (potassium) to 36-Kr (Krypton). Maybe this is the answer to the question you didn't ask but probably meant to ask. (It is impossible for one element to contain 18 elements, you see!) The element with 18 electrons in the 3rd period (= row) of the periodic table is Argon In the first period of the periodic table there…
The periodic table of elements is an arrangement of the elements on a table that allows us to quickly find out some things about a given element and its chemistry. Use the link below to get the full scoop on why the periodic table is arranged the way it is. It's the Related question, "In the periodic table what are the elements arranged by?"
To find the period of an element on the periodic table, you look at the end of the row and see what number is there. For example, if your were trying to find the period of Oxygen, you would look all the way to the right or left side of the table and see what number there is, and you would find that oxygen is in period 2.
Lanthanides and actinides are under period six and seven eventhough they were part of period six and seven. the best way to find Lanthanides and actinides is to find period six or seven. If you go to Barium or Radium, you will have a line that connects that elements and goes down and leads to a another two lines with names of elements. The top one is Lanthanides and bottom is the actinides.
You use a Periodic Table to find the group, period, and the material of the 115 elements. You can find the the number of protons/electrons on the bottom of the symbols(which is arranged in oder). You can the mass number on the VERY bottom of the element's block. You can find out the number of neutrons by subtracting the number of protons/electrons from the mass number.