Metal_and_Resistance

A material's ability to conduct electricity is linked to the form of chemical bonding between the atoms of the material. For example, the atoms of silicon are held together through a 3 dimensional lattice of covalent bondingsharing of electrons between the atoms. This means that there are no free electrons to carry charge through therefore silicon is a good insulator. The atoms in a metals are hold together in a similar manner but through metallic bonding. However, metallic bonding creates a sea of 'delocalised' electrons which are free to move about the positive nuclei. This is because the electrons on the outer shells of the atoms could not fill the entire shell . For example, copper has 29 electrons2 in the first shell, 8 in the second shell, 18 in the third shell, and only 1 in the fourth shell. When influenced by a electric field, the lone electrons will easily be forced to move in the opposite direction to the electric field, effectively producing a current (Andriessen, Pentland, Gaut, McKay, & Tacon, 2008, p. 214). This is why metals are good conductors of electricity. This form of metallic bonding also explains why metals are malleable and The electrons in a conductor are constantly moving, at about 1.6 * 10^6 ms^-1, as explained by the Kinetic Theory (Shadwick, 2002). Because of this motion is random, there is no net movement of charge therefore no current. When a voltage is applied the electrons will drift towards the positive terminal. However, electrons do not travel in straight lines, they might bump into nuclei and even move backwards due to the collision. The average speed of the electrons moving through a conductor is known as their drift velocity, which is only about 10-3 ms-1 (Williams & Pemberton, 2004). The ability of conductors to hinder the movement of electrons is called electrical resistance. When the temperature of a conductor increases the atoms have more energy therefore the lattice vibrates more. Hence the electrons are more likely to run into nuclei thus increasing the resistance. If the width of a conductor increases, there will be more room for the electrons to move therefore decreasing the resistance. Impurities within a conductor distorts the lattice structure and offer more resistance. It is logical to think that if a conductor is made of a metal with high purity and decrease its temperature until there is no vibration in the lattice, the conductor will become a perfect conductor, or a superconductor.