The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

Can you believe the periodic table has been around for over 150 years? Take this quiz to see if you can find the elements. What information do we collect from this quiz? What is the periodic table?

Across a period from left to right, the covalent radius decreases. As you move from left to right across the periodic table, atoms have more electrons in their outer energy level and more protons ...