The periodic table has changed a lot over time. It has adapted to include new discoveries and make it more accurate. Let's break it down:

1. Early Development

   • In 1869, a scientist named Dmitri Mendeleev organized 63 known elements based on their atomic mass. He even guessed some properties of elements that hadn’t been discovered yet.

2. Atomic Number

   • In 1913, another scientist, Henry Moseley, introduced the idea of atomic number. This meant that elements could be arranged differently, and now we recognize over 118 elements!

3. Periodic Law

   • Nowadays, we follow the modern periodic law. This means that the properties of elements depend on their atomic numbers and repeat in a certain way.

4. New Discoveries

   • Scientists have created synthetic elements, which has helped grow the periodic table. We now know about elements past uranium (atomic number 92), and element 118, called oganesson, has been confirmed.

5. Organization

   • The periodic table is organized into groups and periods. There are 7 periods which match the levels of electron shells around an atom.

This evolution of the periodic table helps us better understand the building blocks of our world!