Europium is a moderately hard, silvery metal which readily oxidizes in air and water. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3. Europium is one of the least abundant elements in the universe. Only about 5×10−8% of all matter in the universe is europium.
Protons and Neutrons in Europium
Europium is a chemical element with atomic number 63 which means there are 63 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 Europium are 153.
Main Isotopes of Europium
Europium occurs in 2 natural isotopes: 151Eu and 153Eu. 153Eu is the most common isotope, having a natural abundance of approximately 52%. Of these, 151Eu is very slightly radioactive, decaying by alpha decay with a half-life of 5×1018 years.
Europium-151 is composed of 63 protons, 88 neutrons, and 63 electrons.
Europium-153 is composed of 63 protons, 90 neutrons, and 63 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 Europium is 63. 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 Europium is [Xe] 4f7 6s2.
Possible oxidation states are +2,3.
Most Common Application of Europium
Europium is used in the printing of euro banknotes. It glows red under UV light, and forgeries can be detected by the lack of this red glow. Relative to most other elements, commercial applications for europium are few and rather specialized. Almost invariably, its phosphorescence is exploited, either in the +2 or +3 oxidation state. Europium is one of the elements involved in emitting red light in CRT televisions.
|Number of protons
|Number of neutrons (typical isotopes)
|Number of electrons
|[Xe] 4f7 6s2