Ch 9Elements of Group 13, 14 and 15 — Class 11 Chemistry, concept-first.

In the p-block elements, the last (differentiating) electron enters an outer p-orbital, and since a p-subshell can hold at most six electrons across three p-orbitals, this generates six groups, groups…

The general outer electronic configuration of group 13 elements is ns²np¹, of group 14 elements is ns²np², and of group 15 elements is ns²np³.

Physical and atomic properties vary widely within these three groups because each group spans nonmetals, metalloids and metals.

Oxidation state, the type of bonding formed, and reactivity towards air, water and halogens are the primary chemical properties that describe how the elements of groups 13, 14 and 15 behave.

Oxidation state is the primary chemical property used to classify how these elements bond. The highest oxidation state shown by any p-block element equals the total number of valence electrons (s-elec…

The lighter elements of groups 13, 14 and 15 have small atomic radii and high ionization enthalpies, so removing electrons to form simple cations is energetically expensive; instead they form covalent…

Reactivity towards air or oxygen follows a distinct pattern in each group. Group 13 elements, on heating in air or oxygen, form an oxide of type E2O3 (4E(s) + 3O2(g), heated, → 2E2O3(s)) and can likew…

Most elements of groups 13, 14 and 15 are unaffected by water under ordinary conditions. Aluminium is an exception: on heating it reacts with water to form aluminium hydroxide and hydrogen gas, 2Al(s)…

All group 13 elements react directly with halogens to form trihalides, EX3 (2E(s) + 3X2(g) → 2EX3(s)); thallium is the one exception, forming monohalides (TlX) instead, consistent with its preference…

Catenation is the property by which atoms of the same element link to one another through covalent bonds to form chains and rings.

When a solid element can exist in more than one crystalline form, each with its own physical properties such as colour, density and melting point, the phenomenon is called allotropy, and the individua…

Diamond, graphite, fullerenes, carbon nanotubes and graphene are all allotropes of carbon, differing only in how their carbon atoms are bonded to one another.

Phosphorus exists in several allotropic forms, of which white (or yellow) phosphorus and red phosphorus are the most important.

Because the lighter elements of groups 13, 14 and 15 have small atomic radii and high ionization enthalpies, they do not readily lose electrons to form simple cations; instead they form covalent compo…

Boron trichloride, BCl3, is a covalent molecule in which the central boron atom is sp2 hybridised, using its three hybrid orbitals to form three B-Cl sigma bonds while leaving one unhybridised p-orbit…

In aluminium chloride, AlCl3, the aluminium atom is likewise sp2 hybridised with one vacant, unhybridised p-orbital, exactly analogous to boron in BCl3.

Orthoboric acid, also called boric acid, H3BO3, has a central boron atom bonded to three -OH groups, giving each individual molecule a trigonal planar B(OH)3 shape.

In diborane, B2H6, each boron atom is sp3 hybridised, even though boron itself supplies only three valence electrons.

Silicon dioxide, commonly called silica, is a covalent, three-dimensional network solid rather than a discrete molecule: every silicon atom is covalently bonded, in a tetrahedral arrangement, to four…

Nitric acid, HNO3, is a strong, oxidising mineral acid whose central nitrogen atom is sp2 hybridised. Its bonding cannot be captured by a single Lewis structure: the nitrogen-oxygen bonding is delocal…

Phosphorus forms a whole family of oxyacids, of which orthophosphoric acid (or simply phosphoric acid), H3PO4, is the most important.

Having looked at the general trends and representative molecular structures of groups 13, 14 and 15, this closing section examines the chemistry — preparation, properties and uses — of three specific,…

Borax, Na2B4O7, is one of the most important compounds of boron. The crystalline solid is usually written as Na2B4O7.10H2O, though its structural formula is more accurately given as Na2[B4O5(OH)4].8H2…

Silicones are organosilicon polymers built from a repeating R2SiO unit, where R is typically a methyl (CH3) or phenyl (C6H5) group, the units linked to each other through Si-O-Si bonds; because this…

Ammonia, NH3, occurs naturally in small amounts in air and soil, formed by the decomposition of nitrogenous organic matter such as urea: NH2CONH2 + 2H2O → (NH4)2CO3, which decomposes to 2NH3 + H2O + C…