During the time of Maxwell and Faraday, concerns came about for electropositive and electronegative activities. All of these forms are strongly electropositive and thus lanthanide ions are hard Lewis acids. Caesium is the most electropositive chemical element. It is malleable, ductile, slightly paramagnetic, strongly electropositive and a poor electrical conductor. Cerium is a highly electropositive metal and reacts with water. Organometallic compounds of electropositive metals are superbases, but they are generally strong nucleophiles. Thorium is a highly reactive and electropositive metal. Holmium is quite electropositive and is generally trivalent. They can reduce metal cations that are less electropositive. Therefore, the alkali metals are most electropositive of all. The X ligand is attracted to highly electropositive metals. They all form X ions when reacting with electropositive metals. As calcium is less electropositive than sodium, no calcium will be deposited at the cathode. A silicide is a compound that has silicon with (usually) more electropositive elements. Oxides of more electropositive elements tend to be basic.