wordplay - These Riddles Again?

With the beginning, I can make you totally emotionless

Add a few letters to it and you can even find a special kind of school

In the middle, a special kind of energy awaits you

Something that flows in every living thing, they say

The ending is quite a short one

But it is actually what you do to this riddle

What am I?

Hint (Usefulness Level : 0)

This word is not commonly used in daily conversations

Hint (Usefulness Level : 1)

This word consists of 13 letters

Hint (Usefulness Level : 1 again)

You need to use mathematics when doing (The word)

Hint (Usefulness Level : 2)

The special school in the second line was created a very long time ago (BC)

Hint (Usefulness Level : 2)

The word is actually a part of a subject at school

Hint (Usefulness Level : 2)

What I meant by few letters in the second line was 3 letters exactly

Note :

Will add more hints if no one gets it after a while

Answer

I think I may be getting somewhere here :)

Stoichiometry

Prefix:

Stoic (emotionless) and stoicism (the school)

Infix (thanks to @Duck and @PerpetualJ):

Chi

Suffix

Try (what you do to this riddle)

All the hints add up as well

13 letters, involves math, is part of a subject (chemistry), three letters to turn stoic in stoicism