For a metal rod and
a wooden rod of the same length, which one conducts heat faster? Why? (Extension)
One of the differences between metals and non-metals is that metals can conduct
heat much faster than non-metals. What makes them different in conducting heat?
It is because one has electrons moving freely inside the body and the other
Structure of matter
What is electron? All matters (solids, liquids and gases) are made up of very
tiny things called atoms. Each atom has a nucleus with some electrons moving
around; some electrons are more loosely held by the nucleus and different materials
have different number of electrons at their atoms (Fig a).
Fig a In an atom of a certain material, some electrons
moving around a nucleus.
Fig b Atoms are closely packed inside a solid metal.
In solids, atoms are packed close together (Fig b). For metals, those loosely
held electrons of atoms would no longer be bounded by any atom; they move freely
inside the solid metal. These freely moving electrons are called free
electrons. For non-metals, most electrons are bounded by the atoms.
What do free electrons do
when metals are heated?
When an end of a metal rod is heated, both atoms and free electrons at the hotend
gain energy; atoms vibrate vigorously and free electrons move at a highspeed.
When these high-energy atoms or free electrons collide with their neighbouring
atoms with lower energy, they would lose energy to neighbouringatoms. Since
free electrons are present in metals, metal atoms are hit morefrequently than
non-metal atoms when heated. Hence, metals can be heated muchfaster than non-metals.