Cadmium is a soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. In nuclear industry cadmium is commonly used as a thermal neutron absorber due to very high neutron absorption cross-section of 113Cd. 113Cd has specific absorption cross-section.
Protons and Neutrons in Cadmium
Cadmium is a chemical element with atomic number 48 which means there are 48 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 Cadmium are 108, 110-112, 114.
Main Isotopes of Cadmium
Cadmium occurs in 8 natural isotopes: 106Cd, 108Cd, 110Cd, 111Cd, 112Cd, 113Cd, 114Cd and 116Cd. 113Cd is very slightly radioactive, decaying by beta decay with a half-life of 7.7×1015 years. 114Cd is the most common isotope, having a natural abundance of approximately 28%.
Cadmium-106 is composed of 48 protons, 58 neutrons, and 48 electrons.
Cadmium-108 is composed of 48 protons, 60 neutrons, and 48 electrons.
Cadmium-110 is composed of 48 protons, 62 neutrons, and 48 electrons.
Cadmium-111 is composed of 48 protons, 63 neutrons, and 48 electrons.
Cadmium-112 is composed of 48 protons, 64 neutrons, and 48 electrons.
Cadmium-113 is composed of 48 protons, 65 neutrons, and 48 electrons.
Cadmium-114 is composed of 48 protons, 66 neutrons, and 48 electrons.
Cadmium-116 is composed of 48 protons, 68 neutrons, and 48 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 Cadmium is 48. 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 Cadmium is [Kr] 4d10 5s2.
Possible oxidation states are +2.
Most Common Application of Cadmium
Cadmium is primarily consumed for the production of rechargeable nickel cadmium batteries. In 2009, 86% of cadmium was used in batteries, predominantly in rechargeable nickel-cadmium batteries.
A fully charged Ni-Cd cell contains:
- a nickel(III) oxide-hydroxide positive electrode plate
- a cadmium negative electrode plate
- a separator, and
- an alkaline electrolyte (potassium hydroxide).
|Number of protons||48|
|Number of neutrons (typical isotopes)||108, 110-112, 114|
|Number of electrons||48|
|Electron configuration||[Kr] 4d10 5s2|
Properties of other elements