Reactivity of Group 13 Towards Oxygen

Group 13 elements belong to the boron family. These elements start with the p block. The following elements are present in this group: 

• Boron (B)

• Aluminium (Al)

• Gallium (Ga)

• Indium (In)

• Thallium (Tl),

• Nihonium (Nh)

In this group of elements, boron represents anomalous behaviour, whereas aluminium has metallic properties but is similar to boron. Other elements, i.e. gallium, indium, and thallium are metallic. Sometimes this group is referred to as the boron group family. In this article, we will learn about group 13 reactivity with oxygen and other similar properties. 

Electronic configuration of group 13

• Group 13 outer shell electronic configuration is ns²np¹. 

• Noble gas cores have aluminium and boron present in them.

• Noble gas cores have plus 10 d electrons. 

• There are 14 f electrons plus 10 d- electrons present in thallium noble gas cores. 

• Due to this difference in electronic cores, these elements have different chemical properties and chemistry.

• p block elements show maximum oxidation property which is equal to the total number of valence electrons. 

• The oxidation state of these elements increases when they move towards the right side of the periodic table. 

Existence of these elements 

• Boron 

Boron does not exist in the free state. This element was first discovered by three chemists. It is one of the rare elements which occur as borates, orthoboric acid, and borax. Boron is also sourced from kernite. In India, this element can be found in Sambhar Lake ( Rajasthan) and Puga valley ( Ladakh). Boron shows two types of isotopic forms, ¹⁰B (19%) and ¹¹B (81%). 

• Aluminium 

Aluminium also doesn’t exist in the free state. But it is one of the most abundant elements (8.3% in terms of mass) found in nature after Oxygen (45.5%) and Silicon ( 27.7%). Cryolite and bauxite are some of the important minerals of aluminium. In India, one can find aluminium in the form of mica. 

• Gallium, indium, and thallium

These three elements are less available in nature. And thallium is considered to be a highly toxic element of this group 13. 

Periodic properties of group 13

1. Atomic radii

• As we move down the periodic table of group 13, each element adds an extra shell of electrons. And due to this, the atomic radii increase from top to bottom. 

• But there is a difference between the two elements of the group. Gallium has fewer atomic radii than aluminium. ( Al is 142 pm whereas Ga is 135 pm) . 

• This is due to the variation in the inner core of the electronic configuration. 

• The noble gas core is present in aluminium, but gallium has more than 10 d electrons. Because of these 10 d electrons, there is poor screening for outer electrons. There is also an increased presence of nuclear charge in gallium. 

2. Ionisation enthalpy (IE or ∆ H) 

• Ionisation enthalpy is also irregular in group 13 elements. The enthalpy decreases as we move from AI to TI. 

• 10 d- electrons are present in the inner electronic configuration. It shields the nuclear charge less than p and s electrons. 

3. Electronegativity 

As we move down group 13, the electronegativity decreases. The electronegativity is lesser as we move towards AI from B. There is a decrease due to differences in the atomic sizes of the elements. 

Chemical properties of group 13 elements 

To detach from group 13 elements, elements require loads of energy. This is because all the compounds formed by group 13 elements with oxygen are inert thermodynamically. Boron is the only element in the family that is metalloid. 

• Reactivity of group 13 towards Oxygen 

There is a high amount of reactivity of group 13 towards oxygen. All the elements in this group react with oxygen to form trioxides M2O3. 

4M(s) + O2 (g) → 2M2O3(s)

Thallium can produce Tl2O along with Tl2O3. The reactivity of group 13 elements also increases as we move from one element to another down the group. Whereas boron shows a unique behaviour towards oxygen and doesn’t react. When boron is heated, the amorphous boron reacts with oxygen thus forming B2O3. 

Aluminium, in fact, should react with oxygen thermodynamically, but it is stable. This is because Al2O3 forms a protective coat on the metal surface, making it inert. 

• Reactivity of group 13 towards alkalis and acids

At high temperatures, boron reacts with strong oxidising acids, but it doesn’t react with non oxidising acids such as HCl. But it is reactive towards a hot concentrated mixture composed of H2SO4 and HNO3 to produce boric acid. 

B(s) + 3HNO3 (aq) → H3BO3 (aq) + 3NO2 (g)

This element is also resistant to alkalis ( NaOH and KOH) up to 773 K. After that, boron forms borates. 

2B(s) + 6KOH(s) → 2K3BO3(s) + 3H2(g)

All other elements present in group 13 do react with both oxidising acids, thus releasing hydrogen gas. 

• Reactivity of group 13 towards halogens

Elements in this group react with halogens to form trihalides MX3. But thallium produces TlCl3.

2M(s) + 3X2 (g) → 2MX3

• Acid-base characteristics

Group 13 acid properties decrease as we move down the group. On the other hand, the basic character increases. 

Conclusion

We have learnt about group 13 elements, what makes them unique and their reactivity towards oxygen. This group is usually identified by the three valence electrons. This article also tells you about the significance of compounds of group 13 elements.