1) Chemical property 
In chemistry, a tetravalence is the state of an atom with four electrons available for covalent chemical bonding in its valence (outermost electron shell). An example is methane (CH4): the tetravalent carbon atom forms a covalent bond with four hydrogen atoms. The carbon atom is called tetravalent because it forms 4 covalent bonds. A carbon atom h...
• (n.) The quality or state of being tetravalent; quadrivalence.
Te·trav'a·lence noun (Chemistry) The quality or state of being tetravalent; quadrivalence.