![]() ![]() All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct. The symmetry properties of the crystal are described by the concept of space groups. The positions of the atoms inside the unit cell are described by the set of atomic positions ( x i, y i, z i) measured from a reference lattice point. The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c) aĪnd the angles between them Lattice Angles (alpha, beta and gamma). The long process of radioactive alpha decay of uranium and thorium forms the element Helium. It gets its name from the Greek god Helios, the god of the sun. It exists as a colorless, odorless, tasteless, and non-toxic gas. The unit Cells repeats itself in three dimensional space to form the structure. Helium (He) is an inert gas and belongs to the noble gases, Group 18, of the periodic table. The Crystal structure can be described in terms of its unit Cell. Helium is used in lighter than air balloons and while heavier. particles are doubly ionised helium atoms, He 2+. Helium is the second most abundant element in the universe after hydrogen. Helium is available in pressurised tanks. Helium gas is an unreactive, colourless, and odourless monoatomic gas. (Greek helios, sun), symbol He, inert, colorless, odorless gaseous element. Find Periodic table of elements helium stock images in HD and millions of other royalty-free stock photos, illustrations and vectors in the Shutterstock. Krypton and xenon are used in photographic flash units and in lighthouses, as running an electric current through either element generates a very bright light.The solid state structure of Helium is Face Centered Cubic. Helium is one of the so-called noble gases. Neon is used in sign tubing because it glows bright red when electricity is passed through it. ![]() Helium is also used to inflate the tires of large aircraft, weather balloons, and blimps because it is nonflammable. Helium is used for diluting the pure oxygen in deep-sea diving tanks because the helium has a low solubility in human blood. Argon is used in arc welding and in common light bulbs, as it does not react with the metal at high temperatures. The noble gases are used in industry in arc welding, to dilute the oxygen in deep-sea divers' gas tanks, and to fill light bulbs. Krypton will form a solid with fluorine, and xenon will form a variety of compounds with oxygen and fluorine. The other noble gases will react on a limited scale under very specific conditions. Of the noble gases, only helium and neon are truly inert. In fact, the name of the element helium was derived from the Greek word Helios, used to refer to the sun. They are extremely rare in nature, and none was known until helium was discovered to exist on the sun. These gases were not discovered until the last five years of the 1800s. The elements in this group are helium, neon, argon, krypton, xenon, and radon. This periodic table is created by Dr Kaisa Helttunen and. This means that they do not react with other elements because they already have the desired eight total s and p electrons in their outermost (highest) energy level. Helium 4.002602: 3 Li Lithium 6.94: 4 Be Beryllium 9.0121831: 5 B Boron 10.81: 6 C Carbon 12.011: 7 N. As helium has the same properties (like that of neon, argon, krypton, xenon and radon), it is placed along with these elements (in group 18) and not in group 2. Helium element do not react with other elements and hence it is chemically inert. The group of elements at the far right of the table (Group 18) is known commonly as the noble gases. Helium shows the very similar physical and chemical properties as that of the group 18 elements. Let's look at the other side of the periodic table now. ![]()
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