Element Information, Facts, Properties, Trends, Uses, Comparison with other elements
Actinium is a radioactive chemical element with symbol Ac (not to be confused with the abbreviation for an acetyl group) and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated. Polonium, radium and radon were observed before actinium, but they were not isolated until 1902.
It belongs to group of the periodic table having trivial name .
Read key information and facts about element Actinium
|Group in Periodic Table||-|
|Period in Periodic Table||period 7|
|Block in Periodic Table||f -block|
|Electronic Configuration||[Rn] 6d1 7s2|
|Electronic Shell Structure (Electrons per shell)||2, 8, 18, 32, 18, 9, 2|
|Melting Point||1323 K|
|Boiling Point||3473 K|
How to Locate Actinium on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 89 to find Actinium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Actinium on periodic table look for cross section of group - and period 7 in the modern periodic table.
The element Actinium was discovered by F. O. Giesel in year 1902 in France. Actinium was first isolated by F. O. Giesel in 1902. Actinium derived its name from the Greek aktis, 'ray'.
Giesel obtained from pitchblende a substance that had properties similar to those of lanthanum and named itemanium. André-Louis Debiernehad previously reported the discovery of a new element actinium that was supposedly similar to titanium and thorium; the elements were mistakenly identified as being identical and Debierne's name was chosen, even though in retrospect Debierne's substance could not have included much actual element 89.
Actinium Presence: Abundance in Nature and Around Us
The table below shows the abundance of Actinium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
|ppb by weight (1ppb =10^-7 %)||ppb by atoms (1ppb =10^-7 %)|
|Abundance in Universe||-||-|
|Abundance in Sun||-||-|
|Abundance in Meteorites||-||-|
|Abundance in Earth's Crust||-||-|
|Abundance in Oceans||-||-|
|Abundance in Humans||-||-|
Crystal Structure of Actinium
The solid state structure of Actinium is Face Centered Cubic.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
Unit Cell Parameters
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)
|567 pm||567 pm||567 pm|
and the angles between them Lattice Angles (alpha, beta and gamma).
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. 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.
|Space Group Name||Fm_ 3m|
|Oxidation States||Space Group Number||225|
|Crystal Structure||Face Centered Cubic|
Actinium Atomic and Orbital Properties
Actinium atoms have 89 electrons and the electronic shell structure is [2, 8, 18, 32, 18, 9, 2] with Atomic Term Symbol (Quantum Numbers) 2D3/2.
|Number of Electrons (with no charge)||89|
|Number of Protons||89|
|Number of Neutrons||138|
|Shell structure (Electrons per energy level)||2, 8, 18, 32, 18, 9, 2|
|Electron Configuration||[Rn] 6d1 7s2|
|Valence Electrons||6d1 7s2|
|Main Oxidation States||3|
|Oxidation States||2, 3|
|Atomic Term Symbol (Quantum Numbers)||2D3/2|
Bohr Atomic Model of Actinium - Electrons per energy level
Ground State Electronic Configuration of Actinium - neutral Actinium atom
Abbreviated electronic configuration of Actinium
The ground state abbreviated electronic configuration of Neutral Actinium atom is [Rn] 6d1 7s2. The portion of Actinium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Rn]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 6d1 7s2, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Actinium
Complete ground state electronic configuration for the Actinium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 6d1 7s2
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.
Atomic Structure of Actinium
Actinium atomic radius is 195 pm, while it's covalent radius is - .
|Atomic Radius Calculated|
195 pm (1.95 Å)
|Atomic Radius Empirical|
195 pm (1.95 Å)
|Atomic Volume||22.5422 cm3/mol|
|Van der Waals Radius||-|
|Neutron Cross Section||810|
|Neutron Mass Absorption||0.079|
Atomic Spectrum of Actinium
Actinium Chemical Properties: Actinium Ionization Energies and electron affinity
The electron affinity of Actinium is - .
Ionization Energy of Actinium
Refer to table below for Ionization energies of Actinium
|Ionization energy number||Enthalpy - kJ/mol|
Actinium Physical Properties
Refer to below table for Actinium Physical Properties
|Molar Volume||22.5422 cm3/mol|
Hardness of Actinium - Tests to Measure of Hardness of Element
Actinium Electrical Properties
Actinium is Conductor of electricity. Refer to table below for the Electrical properties ofActinium
Actinium Heat and Conduction Properties
|Thermal Conductivity||12 W/(m K)|
Actinium Magnetic Properties
|Mass Magnetic Susceptibility||-|
|Molar Magnetic Susceptibility||-|
|Volume Magnetic Susceptibility||-|
Optical Properties of Actinium
Acoustic Properties of Actinium
|Speed of Sound||-|
Actinium Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Actinium
|Melting Point||1323 K (1049.85°C, 1921.73 °F)|
|Boiling Point||3473 K (3199.85°C, 5791.73 °F)|
Enthalpies of Actinium
|Heat of Fusion||14 kJ/mol|
|Heat of Vaporization||400 kJ/mol|
|Heat of Combustion||-|
Actinium Isotopes - Nuclear Properties of Actinium
Actinium has 31 isotopes, with between 206 and 236 nucleons. Actinium has 0 stable naturally occuring isotopes.
Isotopes of Actinium - Naturally occurring stable Isotopes: -.
|Isotope||Z||N||Isotope Mass||% Abundance||T half||Decay Mode|