I'm 17, can I claim my brother as a dependent on my taxes if my mom has been unemployed and I have been providing everything he needs?

[Tiki]

If your mother is not claiming you or your brother, you may be able to claim him as a qualifying child. Please ensure you meet the guidelines listed in the link below and that he is younger than you. If you can claim your brother, you would enter him as if he were your child. 

https://www.irs.gov/Credits-&-Deductions/Individuals/Earned-Income-Tax-Credit/Qualifying-Child-Rules