When electron clouds overlap, electrons can move into electron cloud of adjoining atoms. ... Copper is chosen because it can be drawn into long thin wires very easily (it is ductile) and because it is a good conductor of electricity. ... Metals are lustrous or have a silvery surface but this may be easily tarnished by corrosive oxidation in air and water. ... Aluminium is very strong and can be beaten into very thin sheets. ...

• Word Count: 2699
• Approx Pages: 11
• Grade Level: High School

In addition - and this is what the dopant does - charge carriers in the form of extra electrons or -holes- have to be injected into the material. ... Though the resulting material was highly crystalline and of regular structure, it was a black, air-sensitive, infusible and insoluble powder. Ziegler-Natta polymerisation was developed for polymerising alkenes such as ethylene by inserting an unsaturated molecule into the carbon-titanium bond of the growing macromolecule. ...

• Word Count: 6720
• Approx Pages: 27
• Grade Level: High School

Substances are diverse: air, water, rock and wood are all substances. Most substances can be broken down into other substances by chemical means. Any substance that cannot be broken down into other substances by ordinary chemical means is called an element. ... If we divide an atom of gold into smaller subunits, we get electrons, neutrons and protons. ...

• Word Count: 10700
• Approx Pages: 43
• Grade Level: High School