[Physics] Can atoms lose electrons by themselves

Question

I know atoms lose or gain electrons through ionic bonding but when they are by themselves do they lose electrons? I read in a book on metallic bonding which involves free electrons(the lost ones) and the ions itself.

Answer 1

If the atom is capable of $\beta$ + decay, then an electron might be lost after the event because the number of protons in the nucleus would have decreased by one. The tunneling to freedom idea in the comments is impossible because tunneling only happens when there is a finite potential barrier.