Boron is a metalloid chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in both the Solar system and the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals.
Read key information and facts about element Boron
|Group in Periodic Table||13|
|Group Name||boron family|
|Period in Periodic Table||2|
|Block in Periodic Table||p-block|
|Electronic Configuration||[He] 2s2 2p1|
|Melting Point||2075 °C|
|Boiling Point||4000 °C|
|Electronic Shell Structure||[2, 3]|
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 5 to find Boron 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 Boron on periodic table look for cross section of group 13 and period 2 in the modern periodic table.
The element Boron was discovered by Joseph Louis Gay-Lussac in year 1808 in France and United Kingdom . Boron derived its name from borax, a mineral
The table below shows the abundance of Boron in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
|Ppb by weight (1ppb =10^-7 %)|
|Abundance in Universe||1×10-7%|
|Abundance in Sun||2×10-7%|
|Abundance in Meteorites||1.6e-06|
|Abundance in Earth's Crust||8.6e-06|
|Abundance in Oceans||4.4e-06|
|Abundance in Humans||7e-07|
The solid state structure of Boron is Simple Trigonal.
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.
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)
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||R_ 3m|
|Space Group Number||166|
|Crystal Structure||Simple Trigonal|
Boron atoms have 5 electrons and the electronic shell structure is [2, 3] with Atomic Term Symbol (Quantum Numbers) 2P1/2.
|Number of Electrons (with no charge)||5|
|Number of Protons||5|
|Number of Neutrons||6|
|Shell structure (Electrons per energy level)||[2, 3]|
|Electron Configuration||[He] 2s2 2p1|
|Valence Electrons||2s2 2p1|
|Atomic Term Symbol (Quantum Numbers)||2P1/2|
Shell Structure of Boron - Electrons per energy level
The ground state electronic configuration of Neutral Boron atom is [He] 2s2 2p1. The portion of Boron configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [He]. 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 2s2 2p1, electrons in the outermost shell that determine the chemical properties of the element.
Complete ground state electronic configuration for the Boron atom, Unabbreviated electronic configuration
1s2 2s2 2p1
Boron atomic radius is 87 pm, while it's covalent radius is 82 pm.
87 pm (0.87 Å)
|Atomic Volume||4.39471544715 cm3|
|Covalent Radius||82 pm (0.82 Å)|
|Van der Waals Radius||N/A|
|Neutron Cross Section||755 σa/barns|
The electron affinity of Boron is 26.7 kJ/mol
Refer to table below for Ionization energies of Boron
|Ionization energy number||Enthalpy - kJ/mol|
Refer to below table for Boron Physical Properties
|Molar Volume||4.39471544715 cm3|
|Bulk Modulus||320 GPa|
|Mohs Hardness||9.3 MPa|
|Vickers Hardness||4.9×104 MPa|
Boron is Insulator of electricity. Refer to table below for the Electrical properties of Boron
|Electrical Conductivity||0.0001 S/m|
|Resistivity||10000 m Ω|
|Thermal Conductivity||27 W/(m K)|
|Thermal Expansion||6×10-6 K-1|
|Mass Magnetic Susceptibility||-8.7×10-9|
|Molar Magnetic Susceptibility||-9.41×10-11|
|Volume Magnetic Susceptibility||-2.14e-05|
|Speed of Sound||1.62×104 m/s|
Refer to table below for Thermal properties of Boron
|Melting Point||2348 K (2075 °C)|
|Boiling Point||4273 K (4000 °C)|
|Heat of Fusion||50 kJ/mol|
|Heat of Vaporization||507 kJ/mol|
|Heat of Combustion||N/A|
Isotopes of rhodium. Naturally occurring Boron has 2 stable isotope - 10B, 11B.
|Isotope||Isotope Mass||% Abundance||T half||Decay Mode|
|DOT Hazard Class||N/A|
|NFPA Fire Rating||3|
|NFPA Health Rating||2|
|NFPA Reactivity Rating||0|
List of unique identifiers to search the element in various chemical registry databases
|CAS Number - Chemical Abstracts Service (CAS)||CAS7440-42-8|
|Alkali Metals||Alkaline Earth Metals|
|Transition Metals||Post-Transition Metals|