Final answer:
The emitted electron during the decay of carbon-14 into nitrogen-14 is known as a beta particle, which occurs during beta decay.
Step-by-step explanation:
When carbon-14 decays into nitrogen-14, a neutron within the carbon nucleus changes into a proton and an electron. The electron that is emitted as radiation during this process is known as a beta particle. The beta particle is symbolized by the Greek letter β and can also be represented as e- with a charge of -1. The emission of the beta particle during the decay of carbon-14 into nitrogen-14 is an example of beta decay, a process that does not change the overall mass number of the atom but increases the atomic number by one due to the addition of a proton.