Metallic bonding is the result the electrostatic attractive force that occurs between conduction electrons in the form of an electron cloud of delocalized electrons and positively charged metal ions. It may be described as the sharing of free electrons among a lattice of positively charged ions cations. Metallic bonding accounts for many physical properties of metals, such as strength, ductility, thermal and electrical resistivity and conductivity, opacity, and luster.
Metals contain free moving delocalized electrons. When electric voltage is applied, an electric field within the metal triggers the movement of the electrons, making them shift from one end to another end of the conductor. Electrons will move toward the positive side. Metal is a good conduction of heat. Conduction occurs when a substance is heated, particles will gain more energy, and vibrate more.
These molecules then bump into nearby particles and transfer some of their energy to them. This then continues and passes the energy from the hot end down to the colder end of the substance. The electrons in metal are delocalised electrons and are free moving electrons so when they gain energy heat they vibrate more quickly and can move around, this means that they can pass on the energy more quickly.
Silver has a larger atomic radius pm than gold pm , despite the fact that gold has more electrons that silver! For a reason for this see the comment below. Thermal conductivity is similar to electrical in that exciting atoms in one section works to excite and vibrate adjacent atoms. That motion or kinetic energy — not unlike rubbing your hands together to get warm — allows heat to move through the metal.
Alloys, which are a combination of different metallic elements, tend to offer a lower level of thermal conductivity than pure metals. Atoms of different size or atomic weight will vibrate at a different rate, which changes the pattern of thermal conductivity.
If there is less energy transfer between atoms, there is less conductivity. Pure silver and copper provide the highest thermal conductivity, with aluminum less so. Stainless steels provide low thermal conductivity. Some materials, including copper, will readily conduct both heat and electricity. While others, like glass, conduct heat but not electricity. As we have noted before, the selection of the metal for any application probably involves tradeoffs.
Since these other elements are a different size than the base element, they strain the lattice, decreasing conductivity. Even small alloying additions can have a large effect on conductivity. For example, adding 0. In many cases, precipitates decrease conductivity less than solid solution atoms, so one quick method of determining precipitation in metals is by checking its conductivity.
The fourth way that engineers can control conductivity is by changing grain boundaries. Grain boundaries are portions of a metal where two crystal arrangements with a different orientation come together. As you might expect from the other points, grain boundaries have lattice strain which interacts with electrons, reducing their mobility. Fewer grain boundaries means increase resistance.
Na basically steals an electron from Cl. When water experiences a potential change, however, the free-floating ions can move. The net flow of charged atoms is what causes electricity to flow through atoms. The electrons themselves are not actually moving. And yes, this means that pure water is not a good conductor.
Sea water is about a million times more conductive than pure water, and a hundred times more conductive than drinking water. However, since regular drinking water usually has ions dissolved in it from metal, or minerals , drinking water is still around 10, times more conductive than pure water. This sea of electrons occurs because of quantum mechanical effects that give metals no bandgap.
You also learned how engineers can influence the conductivity of a metal by changing the electron mobility. List of Partners vendors. Share Flipboard Email. Terence Bell. Metal Expert. Updated March 02, Featured Video. Cite this Article Format. Bell, Terence. Electrical Conductivity of Metals. Properties of Ionic and Covalent Compounds. Understanding Electrical, Thermal, and Sound Conductors.
Metallic Character: Properties and Trends.
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