Boron Chemical Properties (25 Facts You Should Know)

Boron chemical properties refer to the characteristic properties of a particular element that set it apart from other elements in the periodic table. The definition is as follows:

The chemical properties of Boron are the characteristic properties of the element that are not observed in any other element. It exists in various allotropes forms that can range from crystalline to amorphous. It is also the only non-metallic element in its group and exhibits various unique properties.

In this article, let us discuss the various chemical properties of Boron, like its position in the periodic table, electronegativity, and magnetic properties.

1. Boron Symbol

The chemical symbol for Boron is the alphabet B.

2. Boron Group in Periodic Table

Boron is placed in group 13, or III A, of the modern periodic table. Boron contains three valence electrons. Thus, it belongs to the same group as Aluminum, Gallium, Indium, and Thallium i.e. the “Boron group.”

3. Boron Period in Periodic Table

B is placed in the second period of the modern periodic table. B contains two atomic orbits. Thus, it belongs to the same period as Lithium, Beryllium, Carbon, Nitrogen, Oxygen, Fluorine, and Neon.

4. Boron Block in Periodic Table

B belongs to the ‘p-block’ of the periodic table.

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Symbol of Boron

5. Boron Atomic Number

The atomic number of B is 5. 

6. Boron Atomic Weight

The atomic weight of B is 10.811u.

7. Boron Electronegativity according to Pauling

The electronegativity of B, according to the Pauling scale is 2.04. 

8. Boron Atomic Density

The atomic density of B (in liquid state) is 2.08 g/cm3.

9. Boron Melting Point

The melting point of B is 2349 K ​(2076 °C, ​3769 °F).

10. Boron Boiling Point

The boiling point of B is 4200 K ​(3927 °C, ​7101 °F).

11. Boron van der Waals Radius

The Van der Waal’s radius of B is 192 pm. 

12. Boron Covalent Radius

The covalent radius of Boron is 84±3 pm. 

13. Boron Isotopes

Isotopes are atoms of the same element that have same atomic number but different mass number due to the different number of neutrons present in each type of atom. Lets us discuss the different isotopes of Boron:

B has fifteen types of isotopes, out of which only two types of isotopes are stable and naturally occurring: 11B and 10B

Isotope SymbolNo. of NeutronsAbundance Half-Life
7B2Unstable570(14) ys
8B3Unstable771.9(9) ms
9B4Unstable800(300) zs
10B519.9%Stable
11B680.1%Stable
12B7Unstable800(300) zs
13B8Unstable17.16(18) ms
14B9Unstable12.36(29) ms
15B10Unstable10.18(35) ms
16B11Unstable> 4.6 zs
17B12Unstable5.08(5) ms
18B13Unstable< 26 ns
19B14Unstable2.92(13) ms
20B15Unstable912.4 ys
21B16Unstable5.08(5) ms
Boron Isotope Table

14. Boron Electronic Shell

Electronic shell, or commonly termed as atomic orbit, is the space surrounding the nucleus of an atom that contains the electrons. Let us discuss the electronic shells in boron atom.

B has two electronic shells – K shell (1st electronic shell) and L shell (2nd electronic shell) – with 2 and 3 electrons, respectively.

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Image: Boron Electronic Shells by Greg Robson (CC BY-SA 2.0)

15. Boron Energy of First Ionisation

The first ionisation energy of B is 800.6 kJ/mol.

16. Boron Energy of Second Ionisation

The second ionisation energy of B is 2427.1 kJ/mol.

17. Boron Energy of Third Ionisation

The third ionisation energy of B is 3659.7 kJ/mol.

18. Boron Oxidation States

The oxidation states of Boron are −5, −1, 0, +1, +2, and +3. Boron is mildly acidic, i.e., it forms a mildly acidic oxide when coming in contact with/reacting with oxygen.

19. Boron Electron Configuration

Electronic configuration tells how electrons are distributed in the shell. Let us see the electronic configuration of Boron.

The electronic configuration of Boron is [He] 2s² 2p¹ where [He] signifies the electronic configuration of noble gas Helium, i.e., 1s². 

20. Boron CAS Number

The CAS registry number of Boron is 7440-42-8

21. Boron ChemSpider ID

The ChemSpider ID for Boron is 4575371.

22. Boron Allotropic Forms

Allotropes are physical form of the same element that have same physical state but differ in the arrangement of atom. Let us discuss the different allotropic forms of Boron:

Boron exists in both amorphous and crystalline states. Crystalline boron exhibits four allotropic forms: 

  • α-rhombohedral (α-R)
  • β-rhombohedral (β-R)
  • β-tetragonal (β-T)
  • γ-orthorhombic (γ)

23. Boron Chemical Classification

  • Boron exists in both amorphous and crystalline forms.
  • Boron in crystalline form can be distinguished by its dark, lustrous, and brittle appearance.
  • In its amorphous state, Boron resembles a brown powdery substance.
  • Elemental Boron is extremely rare and its found in low abundance on the earth’s crust. 

24. Boron State at Room Temperature

Boron is classified as a metalloid and exists in a solid state at room temperature.

25. Is Boron Paramagnetic?

Paramagnetic property is the property of an element to get weakly attracted toward an externally applied magnetic field. Let us check Boron’s electromagnetic property.

Boron is paramagnetic in nature. Boron’s electronic configuration is [He] 2s² 2p¹, i.e., it has one unpaired electron in the outermost ‘p-orbital’ of the atom. It can become diamagnetic by losing one unpaired electron from the atom’s outermost shell (B+).

Conclusion

Boron is an electron-deficient metalloid that appears brittle and dark in crystalline form and brown powder in amorphous form. Its properties are similar to those of carbon, forming covalently bonded molecular networks. Boron is commonly used as an additive in polymers, an intermediate in organic synthesis, and a semiconductor dopant.