I am a teenager girl and I wonder if chatting with boys on social media is considered a sin?

The matter is not restricted to this extent. The male-female relationship is based on chastity.

Communication between both sexes is allowed if the manners prescribed by shari'ah (Islamic law) are observed and it was for a purpose deemed valid by shari'ah, such as work, study and so forth. If a relationship exceeds these restrictions it becomes prohibited. In shari'ah, a woman is commanded to avoid anything that might make her an object of desire for men or an object for forbidden feelings.