About Oxygen

Chemical Sing: O  
Sequence Number: 8
Atomic Weight: 15.9994
Temperature of Melting: -218.4
Temperature of Boiling: -182.962  
Electrons by Layers: 2:6
Isotopes: 8  
Atomic Radius: 0.65

Brief History: Oxygen is a Group 16 element. While about one fifth of the atmosphere is oxygen gas, the atmosphere of Mars contains only about 0.15% oxygen. Oxygen is the third most abundant element found in the sun, and it plays a part in the carbon-nitrogen cycle, one process responsible for stellar energy production. Oxygen in excited states is responsible for the bright red and yellow-green colours of the aurora. About two thirds of the human body, and nine tenths of water, is oxygen. The gas is colourless, odourless, and tasteless. Liquid and solid oxygen are pale blue (see picture above) and strongly

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About Hydrogen

Chemical Sing: H
Sequence Number: 1
Atomic Weight: 1.00794
Temperature of Melting: -255.34
Temperature of Boiling: -252.87
Electrons by Layers: 1
Isotopes: 3
Atomic Radius: 0.79

Brief History: Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about about 90% of the universe by weight. Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. Hydrogen gas was used in lighter-than-air balloons for transport but is far too dangerous because of the fire risk (Hindenburg).

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Edison’s vacuum tube.

what he needed to rectify alternating radio signals into DC signals required tooperate headphones. By hooking up Edison’s vacuum tube to a receiving antenna, the tube worked like a diode. When the signal voltage increased in one direction, it made the plate positive (+), and the signal got through. When the signal voltage increased in the other direction of the AC cycle, applying a negative (–) charge to the plate, the signal stopped.

The vacuum tube, also called the electron tube, required a source of electrons to function. In Edison’s original electron tube, the electron source, called the cathode, was the filament that, when heated red-hot, emitted electrons that flew off into the vacuum toward the positively charged plate, called the anode. The effect of heating the cathode to activate the electrons was called thermionic. Other electron tubes used  ligh voltage to pull the electrons out of a cold cathode. Electronic emission also occurred by applying light energy to a photosensitive cathode. Tubes using this effect were called photoelectronic vacuum tubes. Although a variety of methods existed to remove electrons from the cathode, the thermionic vacuum tubes were the most widely used. The cathode was either heated by resistors within or used a separate source of power for heating. The vacuum tube consisted of a glass or metal enclosure with electrode leads brought out through the glass to metal pins molded into a plastic base (Fig. 1.5).

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