Periodic Table

On the periodic table it is separated based on certain trends with the elements. There are different blocks that mark off the different electrons that the element can hold on different levels. Here is an image that shows the location of the blocks: 

Here is a website that explains what the different blocks and letters mean:http://www.gordonengland.co.uk/elements/blocks.htm

Here is another link to a video that identifies the blocks and their use: https://youtu.be/hJ0WwAGSjlc