Eh. No.
Magic and Mentalism are related, but separate genres of performance art. There are two very significant and important differences between them -
1) Magic encourages the suspension of disbelief, willing or unwilling. Mentalism creates belief.
The difference here is that magic is basically watched with an unspoken social contract that everyone involved knows there's tricks going on, and it's fun to just let that happen and enjoy the show. The very best magicians create moments of borderline belief, but in general everyone knows it's just all fun.
Mentalism creates belief. No matter what your claim is - whether you're claiming to be a telepath, clairvoyant, psychologist, or intuitive - you perform it as if it was real. The very best mentalists use premises and methods that seem just real enough to make people question whether they really are tricks. There are so many people that think Derren Brown is genuinely doing what he claims to be doing, even though he always says he's not.
2) Magicians perform tricks, mentalists employ systems.
Because of that unspoken social contract that it's all tricks, magic is expected to succeed. The magician is the all powerful god character, who, eventually, will always win. The journey through that challenge can be really beautiful and fun, but the end result is generally known as soon as the performance begins. That's a big part of why audiences always know it's tricks. Tricks always work. Mentalists employ systems - sometimes systems don't work out. That's why mentalists don't mind the occasion miss or failure. It can be leveraged to make everything seem more real, and create more belief.
Mentalism is much more character and presentation focused than magic is.
Because of that, you can't just "put a little mentalism" in a show. You can do mentalism, or you can do magic - I don't honestly believe you can do both in the same show - it will tip one way or the other. That's a more nuanced discussion for another time, though.
So, if you do things that are clearly impossible - like change a written guess into the actual card selected - you're doing magic with a mental theme, which is mental magic. A mentalist would do it in such a way that it seems genuinely possible - having the actual card in an envelope that's been in plain view the whole time, or writing a prediction detailing the actions that will be taken, or just showing the correct card out of the deck rather than drawing and changing it - depending on the premise of the mentalist's powers.