What is a free electron? Explain conducting and non-conducting materials in terms of it.

In atoms, electrons move around the nucleus where protons remain bound. In some material like metals, under normal circumstances, the attractive force between the valence electrons (outermost ones) and nucleus is comparatively very small.

During the formation of metallic materials, these electrons get separated from their parent atom and move in a random manner. Such electrons are known as Free electrons.

These free electrons are responsible for their electricity conducting property.