Because ancient people are dumb.

In Avatar: The Last Airbender, Lightning is part of Firebending.

In Chinese culture its actually: 金木水火土

There is apparantly 5 elements. And Metal (金) and Earth (土) are separate elements. In this universe Toph Beifong is not an Earthbender, but can only do Metalbending. Lolol.

There should be a 电 （Electricity）

Funny how Air isn’t even in the Chinese version of the elements, so:

金木水火土电 and 气

Metal Wood Water Fire Earth Electricity Air

7 Elements to conquer the world?

Might as well just pull up the periodic table lmao.