![]() ![]() ![]() Both of these isotopes are stable and no radioactive decay can be observed. 4He is the most abundant form among them and its abundance is given as 99%. Since helium is a noble gas, it only shows zero oxidation state. This is because helium is an inert gas that will not undergo chemical reactions. In the periodic table of elements, helium is categorized as an s block element but is placed in the right side corner of the table. This makes it a gas for a wider range of temperatures. The boiling point of helium is given as -268 oC. The melting point of helium is about -272.2 oC, which is a very low value. It exists as a monoatomic gas.įigure 1: Chemical Structure of Helium Atom Helium is considered as the second most abundant element in the universe. At room temperature and pressure, helium is a colorless and odorless gas. Therefore, the atomic mass of helium is 4.002602 amu. An atom of helium is composed of 2 protons and 2 neutrons in the nucleus along with 2 electrons in its 1s orbital. The electron configuration of helium is 1s 2. Helium is an element that has the atomic number 2 and is a gaseous substance. Key Terms: Atomic Mass, Atomic Number, Deuterium, Helium, Hydrogen, Isotopes of Helium, Protium, Tritium What is the Difference Between Helium and Hydrogen What are the Similarities Between Helium and HydrogenĤ. – Properties, Isotopes, Reactions, and Applicationsģ. The main difference between helium and hydrogen is that helium atom exists as a monoatomic gas in the atmosphere whereas hydrogen exists as a diatomic gas in the atmosphere. Due to the very light weight of these gases, they are used to fill air balloons. Due to the characteristic features of hydrogen and helium, there are many applications of these gases in industry. Therefore, they are the smallest and lightest atoms on earth. Relative Atomic Mass of Chlorine: 35.Hydrogen and Helium are the first two elements that are found in the periodic table of elements. Relative Atomic Mass of Neon: 20.1797 amu Relative Atomic Mass of Uranium: 238.0289 amu Relative Atomic Mass of Cesium: 132.905429 amu Relative Atomic Mass of Cupper: 63.546 amu Relative Atomic Mass of Oxygen: 15.9994 amu Relative Atomic Mass of Carbon: 12.0000 amu Relative Atomic Mass of Hydrogen: 1.008 amu The relative atomic mass of some important elements are as follows: Since such an extremely small mass cannot be measured by any balance, this is why relative atomic masses are used. The masses of the atoms vary from 10 -24 to 10 -23 grams. The relative atomic mass of C is 12.0000 amu whereas that of H is 1.008. It is the 1/12th of the mass of one atom of 12C. The relative atomic mass is expressed in atomic mass unit (amu). The mass of one atom of magnesium is two times the mass of one atom of carbon, therefore relative atomic mass of magnesium would be 24. “The mass of one atom of an element compared with the mass of one atom of carbon taken as 12 is called relative atomic mass of the element.” Lithium, for example, has three protons and four neutrons, giving it a mass number of 7. This example may lead you to believe that atoms have the same number of protons and neutrons, but a further examination of the table above will show that this is not the case. Since 2+2=42+2=4, we know that the mass number of the helium atom is 4.įinally, the helium atom also contains two electrons, since the number of electrons must equal the number of protons. Its atomic number is 2, so it has two protons in its nucleus. ![]() The mass number (represented by the letter A) is defined as the total number of protons and neutrons in an atom.Ĭonsider the element helium. ![]()
0 Comments
Leave a Reply. |