Lead is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point. Lead is widely used as a gamma shield. Major advantage of lead shield is in its compactness due to its higher density. Lead has the highest atomic number of any stable element and concludes three major decay chains of heavier elements.
Protons and Neutrons in Lead
Lead is a chemical element with atomic number 82 which means there are 82 protons in its nucleus. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs.
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. Neutron number plus atomic number equals atomic mass number: N+Z=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.
For stable elements, there is usually a variety of stable isotopes. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Mass numbers of typical isotopes of Lead are 204-208.
Main Isotopes of Lead
Lead occurs in 4 natural isotopes: 204Pb, 206Pb, 207Pb and 208Pb. 208Pb is the most common isotope, having a natural abundance of approximately 52%.
Lead-204 is composed of 82 protons, 122 neutrons, and 82 electrons.
Lead-206 is composed of 82 protons, 124 neutrons, and 82 electrons.
Lead-207 is composed of 82 protons, 125 neutrons, and 82 electrons.
Lead-208 is composed of 82 protons, 126 neutrons, and 82 electrons.
Electrons and Electron Configuration
The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. Therefore, the number of electrons in neutral atom of Lead is 82. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.
Electron configuration of Lead is [Hg] 6p2.
Possible oxidation states are +2,4.
Most Common Application of Lead
Lead is widely used for car batteries, pigments, ammunition, cable sheathing, weights for lifting, weight belts for diving, lead crystal glass, radiation protection and in some solders. The largest use of lead in the early 21st century is in lead–acid batteries. The lead in batteries undergoes no direct contact with humans, so there are fewer toxicity concerns. In the late 19th century, lead’s toxicity was recognized, and its use has since been phased out of many applications.
|Number of protons
|Number of neutrons (typical isotopes)
|Number of electrons