In an atom why don’t the electrons float away ? The float around in the electron cloud but what keeps them from floating away ?

If an electron is in the electric field of a nucleus, the electron can occupy only certain energy levels. When it is sitting on one of these energy levels, it does not radiate, it does not loose energy.

Clouds are made of water droplets and ice crystals. A cloud's individual particles are so small, Also  that warm air rising from the earth's surface is able to keep them floating in the air.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme