Question

periodic properties of 3a group

Answer 1

Organic Chemistry Glossary

Search Search

 

Sign in

 Expand/collapse global hierarchy

 Home 

 

 Bookshelves 

 

 Inorganic Chemistry 

 

 Supplemental Modules (Inorganic Chemistry) 

 

 Descriptive Chemistry 

 

 Elements Organized by Block 

 

 p-Block Elements 

 

 Group 13: The Boron Family 

 Expand/collapse global location

Group 13: Physical Properties of Group 13

Last updatedMay 15, 2017

Group 13: Chemical Reactivity

Chemistry of Boron (Z=5)

picture_as_pdf

LMS

Donate

The boron family contains the semi-metal boron (B) and metals aluminum (Al), gallium (Ga), indium (In), and thallium (Tl).

Properties and Periodic Trends

These elements are found in Group 13 (XIII) of the p block in the Periodic Table of Elements. Aluminum, gallium, indium, and thallium are metallic. They each have three electrons in their outermost shell (a full s orbital and one electron in the p orbital) with the valence electron configuration ns2np1. The boron family adopts oxidation states +3 or +1. The +3 oxidation states are favorable except for the heavier elements, such as Tl, which prefer the +1 oxidation state due to its stability; this is known as the inert pair effect. The elements generally follow periodic trends except for certain Tl deviations:

Atomic radius increases down the group (Tl has the largest atomic radius.)

Electrode potential increases down the group (reactivity decreases down the group)

Ionization Energy decreases going down the group (because the electrons are farther from the core and therefore are easier to remove; Tl does not fit this trend)*

Table 1: Properties & Trends of Group 3 ElementsBoronB510.8112076-801AluminumAl1326,9815660-1.68578GalliumGa3169.72329.8-0.56558IndiumIn49114.8181560.34558ThalliumTh81205.383303+0.72589

Boron

Boron is the first element of Group 13 and is the only metalloid of the group. Its chemical symbol is B, and it has an atomic number of 5. Boron has the electron configuration [He] 2s22p1and prefers an oxidation state of +3. Boron has no natural elemental form; it forms compounds which are abundant in the Earth's crust. Boron is an essential nutrient for plants. There are a few locations where boron ores, known as borax, are found in great concentrations. Due to its lack of a complete octet, boron is a Lewis acid. It tends to forms hydrides, the simplest of which is diborane, B2H6B2H6. Boron hydrides are used to synthesize organic compounds. One of the main compounds used to form other boron compounds is boric acid, which is a weak acid and is formed in the following two-step reaction:

B2O3(s)+3H2O(l)→2B(OH)3(aq)(1.1)(1.1)B2O3(s)+3H2O(l)→2B(OH)3(aq)

B(OH)3(aq)+2H2O(l)→H3O+(aq)+B(OH)−4(aq)(1.2)(1.2)B(OH)3(aq)+2H2O(l)→H3O(aq)++B(OH)4(aq)−

Boron can be crystallized from a solution of hydrogen peroxide and borax to produce sodium perborate, a bleach alternative. The bleaching ability of perborate is due to the two peroxo groups bound to the boron atoms.

Aluminum

Aluminum is the most important metal in the boron family, with the chemical symbol Al and atomic number 13. It is used in lightweight alloys and is an active metal. It has the electron configuration [Ne] 2s22p1, and usually adopts a +3 oxidation state. This element is the most abundant metal in the Earth's crust (7.5-8.4%). Even though it is very abundant, before 1886 aluminum was considered a semiprecious metal; it was difficult to isolate due to its high melting point. Aluminum is very expensive to produce, because the electrolysis of one mole of aluminum requires three moles of electrons:

Al3++3e−→Al(l)(1.3)(1.3)Al3++3e−→Al(l)

Aluminum is a soft, malleable metal that is silver or gray in color. It is highly reactive, and therefore found in nature in compounds. Aluminum does not appear to react with water because it is aluminum is protected by a layer of Al2O3; this effect is known as anodizing. The thickness of the Al2O

Answer 2

The above answer is correct check that answer ok