![]() ![]() Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. Interest in silver helped initiate widespread extraction and use of lead in ancient Rome. Galena is a principal ore of lead which often bears silver. Since lead is easily extracted from its ores, prehistoric people in the Near East were aware of it. Like the lighter members of the group, lead tends to bond with itself it can form chains and polyhedral structures. Exceptions are mostly limited to organolead compounds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. ![]() Its weak metallic character is illustrated by its amphoteric nature lead and lead oxides react with acids and bases, and it tends to form covalent bonds. ![]() Lead is a relatively unreactive post-transition metal. Lead is toxic, even in small amounts, especially to children. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. It tarnishes to a dull gray color when exposed to air. When freshly cut, lead is a shiny gray with a hint of blue. Lead is soft and malleable, and also has a relatively low melting point. It is a heavy metal that is denser than most common materials. Therefore, there are various non-equivalent definitions of atomic radius.Lead is a chemical element with the symbol Pb (from the Latin plumbum) and atomic number 82. However, this assumes the atom to exhibit a spherical shape, which is only obeyed for atoms in vacuum or free space. The atomic radius of a chemical element is a measure of the distance out to which the electron cloud extends from the nucleus. It must be noted, atoms lack a well-defined outer boundary. The atomic radius of Gold atom is 136pm (covalent radius). Note that, each element may contain more isotopes, therefore this resulting atomic mass is calculated from naturally-occuring isotopes and their abundance. The atomic mass is carried by the atomic nucleus, which occupies only about 10 -12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. The atomic mass or relative isotopic mass refers to the mass of a single particle, and therefore is tied to a certain specific isotope of an element. Mass numbers of typical isotopes of Gold are 197. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.įor stable elements, there is usually a variety of stable isotopes. Neutron number plus atomic number equals atomic mass number: N+Z=A. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10 -19 coulombs. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. Gold is a chemical element with atomic number 79 which means there are 79 protons in its nucleus. Atomic Number – Protons, Electrons and Neutrons in Gold ![]()
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