Group 13: Boron Family

Group 13 elements are members of the boron family. This group includes Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), Thallium (Tl), and Nihonium (Nh). Boron is a semimetal and forms borides, borates and boronates. The chemistry of Group 13 elements is also influenced by their position on the Periodic Table. It is first group in the p-block. These elements have 3 electrons in their valence shell (Liao, Huang & Chen, 2010).


1. Electronic Configuration

General electronic configuration of group 13 is ns2 np1 while the electronic configuration of Group 13 members is as follows (Jones, 2011).


B [5] 1s2 2s2 2p1 or [He] 2s2 2p1
Al [13] 1s2 2s2 2p6 3s2 3p1 or [Ne] 3s2 3p1
Ga [31] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 or [Ar] 3d10 4s2 4p1
In [49] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p1 or [Kr] 5s2 4d10 5p1
Tl [81] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p1 or [Xe] 6s2 4f14 5d10 6p1
Nh [113] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p1 or [Rn] 7s2 5f14 6d10 7p1


2. Characteristics of Group 3 elements


2.1. Oxidation state of Group 3 elements

Group 13 elements have three electrons in the valence shell. The np1 oxidized condition is represented by 1 of such electrons, while the s-orbital states are occupied by the others 2. The s orbital is reluctant to bond, but is drawn closer to the nucleus by the nuclear charge. Compared to the +3 oxidized position, the +1 oxidative regime is the greater robust option. The inactive pairing phenomenon elucidates the phenomenon. This effect causes a tendency to form +1 ions. It is more pronounced in thallium. It also affects the heavier members of the group. Members of grouping 13 may take on oxidized numbers of either one, three, or two. Complex ions of Ga(II) are in a +2 oxidation state, but unstable due to kinetic factors (Van, et al., 2013).


2.2. Inert pair effect

Among the heavier p-block elements, group 13 elements exhibit the inert pair effect. This phenomenon refers to the reluctance of the outermost shell s- electrons to participate in chemical bonding. It is also the reason for the formation of lower oxidation states of elements in this group. The idle pairing mechanism is responsible for creating the oxidized levels of grouping 13 substances. As a result, their ionized sensitivity rises. However, the magnitude of this increase is not consistent with the general trend of the periodic table.


3. Covalent character

The group 13 elements form both ionic and covalent compounds. Several Group 13 elements form covalent compounds. These elements have a +1 oxidation state and are relatively higher in electronegativity. They react at high temperatures to form trioxides. They tend to form trihalides that usually contain Lewis bases. The s orbiting is pulled forward towards these nuclei as the functional nuclear charges rises. This causes the size of an atom to increase. That’s also the cause of such observed rise in valence electrons density. The actual nuclear charge increases by 32 from indium to thallium (Liao, Huang & Chen, 2010).


4. Anomalous behavior of Boron

Among the elements in the group 13, Boron exhibits anomalous behavior. The reasons behind its unusual behavior is that boron has a relatively small atomic size and is very hard. Besides, it is chemically inert at room temperature. In addition, it has a high boiling and melting point. Boron’s anomalous behavior is based on its diagonal relationship with other elements in the same group. This relationship is also reflected in the way it reacts with other elements. Boron also exhibits allotropy, which is the tendency for an element to have a +1 oxidation state when compared to the other elements of the same group. This tendency increases as the group progresses down the periodic table. It also explains the tendency for elements in the group to combine with certain metals at elevated temperatures (Jones, 2011).


5. Trend in the physical properties

Although their atomic radii are much smaller than those of group II elements, group 13 elements show a similar trend in their ionization enthalpies. Melting and boiling point of this group also show a different behavior (Van, et al., 2013).


5.1. Atomic and ionic radii

Atomic and ionic radius of group 13 elements increases gradually from boron to thallium while ionic and atomic radii of nihonium is unknown.

Atomic radius group 13 periodic table


Figure 1: Atomic radius of Group 13 elements


Ionic radius group 13 periodic table


Figure 2: Ionic radius of Group 13 elements


5.2. Ionization energy

First ionization energies of this group elements are lower than group II elements.
Ionization energy of group 13 elements show irregular behavior from boron to Thallium. First ionization energy of nihonium is not known. Ionization energy of group 13 elements in kilo joule per mole

First ionization energy group 13 periodic table


Figure 3: First Ionization Energy of the Group 13 elements

5.3. Electronegativity

Electronegativity of group 13 elements increase from Al to Tl except boron which has highest electronegativity than other member of its group. Electronegativity of nihonium is not known.


B     2.0

Al    1.5

Ga   1.6

In    1.7

Tl    1.8

5.4. Electrpositivity

Electropositivity is the tendency of an atom to lose electrons
Electropositive elements tend to give away their electrons in chemical reactions. Compared to group 2 and group 1, group 13 elements are relatively less electropositive and have lower ionization enthalpy. Electropositive group 13 elements have a tendency to form a +1 ion. Group 13 elements are icosahedral. Their trihalides are potent Lewis acids. They also react with Lewis bases to form a Lewis acid-base adduct. These compounds are thermodynamically stable. They form trioxides and trihalides at high temperatures.


5.5. Melting and boiling point

The boiling points of the substances comprising cluster 13 fall through highest to lowest, while their melting points behave irregularly.


melting and boiling points group 13 periodic table


Figure 4: Melting and Boiling Points of the Group 13 elements


You want to know about all the Groups of the Periodic Table?


6. Chemical properties

Boron does not interact with water, but only metals to form borides. Boron also acts as a non-metal chemically. The basic character of the oxides of group 13 elements increases with decreasing group. Their acidic character also decreases (Van, et al., 2013).


6.1. Reaction with oxygen

Group 13 elements react with oxygen and form corresponding oxides.Boron react with oxygen at very high temperature.

Reaction of Group 13 elements with Oxygen

Scheme 1: Reaction of Group 13 elements with Oxygen


6.2. Reaction with water

Aluminum reacts with water and form aluminum hydroxide. While other members of group 13 do not react with water.

Reaction of Group 13 elements with water

Scheme 2: Reaction of Group 13 elements with water


6.3. Reaction with halogens

Group 13 elements react with halogens and form corresponding trihalides.

Reaction of Group 13 elements with halogens

Scheme 3: Reaction of Group 13 elements with halogens



Among the long periodic table of elements Group 13 contains the Alkali metals and Boron family. These elements are found in nature and in various industries. Extremely reactive, these elements combine together water to generate potent alkalis. They are also used in ceramics. They are also reactive with halogens. They have a lustrous appearance and high boiling points. The elements of this group have three valence electrons and are reactive. They are used in ceramics, colored compounds, ductile metals, and malleable metals. They can react with halogens and hydrogen. They are also found in nature.



1. Asay, M., Jones, C., & Driess, M. (2011). N-Heterocyclic carbene analogues with low-valent group 13 and group 14 elements: syntheses, structures, and reactivities of a new generation of multitalented ligands. Chemical reviews, 111(2), 354-396.
2. Liao, Y. F., Chiu, Y. T., Huang, C. S., Ko, E. W. C., & Chen, Y. R. (2010). Presurgical orthodontics versus no presurgical orthodontics: treatment outcome of surgical-orthodontic correction for skeletal class III open bite. Plastic and reconstructive surgery, 126(6), 2074-2083.
3. Van Nood, E., Vrieze, A., Nieuwdorp, M., Fuentes, S., Zoetendal, E. G., de Vos, W. M. & Keller, J. J. (2013). Duodenal infusion of donor feces for recurrent Clostridium difficile. New England Journal of Medicine, 368(5), 407-415.