Hydrogen and Helium
HELIUM
CONTENTS
INTRODUCTION………………….….……………………
PROPERTIES……………………………….………………
OCCURRENCE……………………………………………
USES………………..………………………………………
BIBLIOGRAPHY……...……………………………………
INTRODUCTION
Heliums name comes from the Greek word “helios”, meaning sun. Helium is odourless and colourless and remains as a gas at room temperature; this chemical element is abbreviated as He. Helium has two protons in its nucleus whereas the atomic number of helium is 2 and is listed in group VIII of the periodic table. As a noble gas helium is almost chemically inert, unreactive. After hydrogen, helium is the most abundant element in the universe.
During an eclipse in 1868, French astronomer Pierre Janssen discovered helium. After Helium was proven to be an element it was named by a British chemist Sir Edward Frankland and British astronomer Sir Joseph Norman Lockyer. British chemist Sir William Ramsay, who discovered it in cleveite mineral containing uranium, isolated the gas from the outside world in 1895. Later in 1907 British physicist Sir Ernest Rutherford showed that the nuclei of the helium atoms contained positively charged nuclear particles also known as alpha particles.
PROPERTIES
Besides hydrogen, helium is the lightest of all gases. The atomic weight of helium is 4.0026. In phase helium I: Helium becomes a liquid at -268.9°C, phase helium II: below
-270.98°C becomes a superfluid. Helium becomes solid at -272.2°C at pressures above 26 atmospheres, helium boils at -268.9°C and has a density of 0.1664 g/litre at 20°C and one atmosphere.
The stable isotopes of helium are a rare form of helium-3 and the most common form of helium-4. Isotopes from helium-5 to helium-10 are unstable and rapidly decay, these are only known from certain nuclear reactions and experiments with particle accelerators.
Because helium’s’ electron shell is always full, making reactions with other elements is difficult and the resulting compounds would be unstable. However
CONTENTS
INTRODUCTION………………….….……………………
PROPERTIES……………………………….………………
OCCURRENCE……………………………………………
USES………………..………………………………………
BIBLIOGRAPHY……...……………………………………
INTRODUCTION
Heliums name comes from the Greek word “helios”, meaning sun. Helium is odourless and colourless and remains as a gas at room temperature; this chemical element is abbreviated as He. Helium has two protons in its nucleus whereas the atomic number of helium is 2 and is listed in group VIII of the periodic table. As a noble gas helium is almost chemically inert, unreactive. After hydrogen, helium is the most abundant element in the universe.
During an eclipse in 1868, French astronomer Pierre Janssen discovered helium. After Helium was proven to be an element it was named by a British chemist Sir Edward Frankland and British astronomer Sir Joseph Norman Lockyer. British chemist Sir William Ramsay, who discovered it in cleveite mineral containing uranium, isolated the gas from the outside world in 1895. Later in 1907 British physicist Sir Ernest Rutherford showed that the nuclei of the helium atoms contained positively charged nuclear particles also known as alpha particles.
PROPERTIES
Besides hydrogen, helium is the lightest of all gases. The atomic weight of helium is 4.0026. In phase helium I: Helium becomes a liquid at -268.9°C, phase helium II: below
-270.98°C becomes a superfluid. Helium becomes solid at -272.2°C at pressures above 26 atmospheres, helium boils at -268.9°C and has a density of 0.1664 g/litre at 20°C and one atmosphere.
The stable isotopes of helium are a rare form of helium-3 and the most common form of helium-4. Isotopes from helium-5 to helium-10 are unstable and rapidly decay, these are only known from certain nuclear reactions and experiments with particle accelerators.
Because helium’s’ electron shell is always full, making reactions with other elements is difficult and the resulting compounds would be unstable. However
Bibliography: Encyclopedias //encarta.msn.com/artcenter_0/Encyclopedia_Articles.html#tcsel //en.wikipedia.org/wiki/Main_Page Microsoft student Books Helium and its uses Websites //au.images.search.yahoo.com/images //www.fotosearch.com/photos-images/helium.html