Discovered : by Sir William Ramsay in London, and independently by P.T. Cleve and N.A. Langlet in Uppsala, Sweden in 1895.
Origin : The name is derived from the Greek ‘helios’,sun.
Description :A colourless, odourless gas that is totally unreactive. It is extracted from natural gas wells, some of which contain gas that is 7% helium. It is used in deep sea diving for balloons and, as liquid helium, for low temperature research. The Earth’s atmosphere contains 5 parts per million by volume, totalling 400 million tons, but it is not worth extracting it from this source at present.
Atomic No:2 MAss No:4
- Protein Design: Automated protein discovery and synthesis
In this paper I describe (theoretically) the method(s) of automated protein discovery and synthesis.
- What are Compound Microscopes?
Most of the microscopes used today are compound. A compound microscope features two or more lenses. A hollow cylinder called the tube connects the two lenses. The top lens, the one people look through, is called the eyepiece. The bottom lens is known as the objective lens. Below the two lenses is...
- What's In Your Beverage? How to Ensure Quality Control with CO2 Analytical Support
Calibration standards, performance audits, and the FDA's never-ending safety, labeling, and inspection requirements are just the tip of the iceberg when it comes to dealing with the increasingly stringent quality control standards of the beverage industry. As these quality standards become...
- Features of the Scanning Tunneling Microscope
The scanning tunneling microscope (STM) invented by Heinrich Rohrer and Gerd Binnig in the 1980s still manages to do a great job today and competes with more advanced microscope types. The scanning tunneling microscope is used for studying the surface atoms that are found on various materials. The...
- Chemical Safety
People use chemicals every day for a wide array of purposes, which can include work and house hold duties. Many of us fail to realize that we are actually handling potentially deadly chemicals when we simply clean the bathroom or wash the car. This brings to mind the reason why chemical safety is...
A gas formed by boiling or evaporating a liquid.
A rare metallic element found in gadolinite and forming compounds resembling those of yttrium. Symbol: Yb, at. wt.: 173.04, at. no.: 70, sp. gr.: 6.96. Cf."rare-earth element."
A substance whose aqueous solutions do not conduct electricity.
Compounds that contain only carbon and hydrogen.
Differential Thermal Analysis (DTA)
A technique for observing the temperature, direction, and magnitude of thermally induced transitions in a material by heating/cooling a sample and comparing its temperature with that of an inert reference material under similar conditions.
Covalent bond in which electron density is symmetrically distributed.
Water containing Fe3+, Ca2+, and Mg2+ ions, which forms precipates with soap.
Physical properties of solutions that depend upon the number but not the kind of solute particles present.
A system in which controlled nuclear fisson reactions generate heat energy on a large scale, which is subsequently converted into electrical energy.
Process of reducing the concentration of a solute in solution, usually simply by mixing with more solvent.
Compounds containing predominantly covalent bonds.
A device used to measure optical activity.
Ability to conduct electricity.
The rate at which a particular substance will vapourize (evaporate) when compared to the rate of a known substance such as ethyl ether. This term is especially useful for health and fire-hazard considerations.
H3P04, Colorless liquid or rhombic crystals, decomposes before it will boil. Used mostly in the metal etchant. Used in cleaning operations to remove encrusted surface matter and mineral scale found on metal equipment such as boilers and steam producing equipment. Also used to brighten metals and remove rust.
Classification of liquid substances that will burn on the basis of flash points. A combustible liquid means any liquid having a flash point at or above 37.8°C (100°F) but below 93.3°C (200°F), except any mixture having components with flash points of 93.3°C (200°F) or higher, the total of which makes up 99 percent or more of the total volume of the mixture.
An algebraic increase in the oxidation number, may correspond to a loss of electrons.
A subatomic particle having a mass of 0.00054858 amu and a charge of 1-.
Protection of a metal (making ir a cathode) against corrosion by attaching it to a sacrifical anode of a more easily oxidized metal.
Nuclear Binding Energy
Energy equivalent of the mass deficiency, energy released in the formation of an atom from the subatomic particles.