If you have allergies, pregnancy can make your symptoms worse. But you're right to worry about taking allergy medicine during pregnancy. Pregnant women shouldn't take some allergy drugs. Certain antihistamines, however, are safe.
free radical. (chemistry). An atom or a diatomic or polyatomic molecule which possesses one unpaired electron. Also known as a radical.ree radical. in chemistry, a molecule or atom that contains an unpaired electron but is neither positively nor negatively charged. Free radicals are usually highly reactive and unstable.
It is the chemistry of radioactive elements such as the actinides, radium and radon together with the chemistry associated with equipment (such as nuclear reactors) which are designed to perform nuclear processes.uclear chemistry is the subfield of chemistry dealing with radioactivity, nuclear processes, such as nuclear transmutation, and nuclear properties.