INTRODUCTION
We have learnt earlier that the p-block elements are placed in groups 13 to 18 of the periodic table. Their valence shell electronic configuration is ns2 np1–6 (except He which has 1s 2 configurations). The properties of p-block elements similar to others are greatly influenced by atomic sizes, ionisation enthalpy, electron gain enthalpy and electronegativity. The absence of d- orbitals in the second period and the presence of d or d and f orbitals in heavier elements (starting from the third period onwards) causes considerable effects on the properties of elements. In addition, the presence of all three types of elements; metals, metalloids and non-metals brings diversification in the chemistry of these elements. We have already learnt the chemistry of elements of Groups 13 and 14 of the p-block of the periodic table in Class XI, you will learn the chemistry of the elements of subsequent groups in this Chapter.
Group 15 includes nitrogen, phosphorus, arsenic, antimony, bismuth and moscovium. As we move down the group, there is a shift from non-metallic to the metallic character through metalloids character. Nitrogen and phosphorus are non-metals, arsenic and antimony metalloids, and bismuth and moscovium are metals. Molecular nitrogen comprises 78% by the volume of the atmosphere. In the earth’s crust, it occurs as sodium nitrate, NaNO3 and potassium nitrate. It is found in the form of proteins in plants and animals. Phosphorus occurs in minerals
The p-Block Elements of the apatite family, Ca9 (PO4 )6. CaX2 (X = F, Cl or OH) (e.g., fluorapatite Ca9 (PO4 )6. CaF2) which are the main components of phosphate rocks. Phosphorus is an essential constituent of animal and plant matter. It is found in bones as well as in living cells. Phosphoproteins are present in milk and eggs. Arsenic, antimony and bismuth are found mainly in the form of sulphide minerals. Moscovium is a synthetic radioactive element. Its symbol is Mc, atomic number 115, atomic mass 289 and electronic configuration [Rn] 5f 146d 107s 2 7p 3. Due to its very short half-life and availability in very little amount, its chemistry is yet to be studied.
CONTENT
Group 13 Elements: General introduction, electronic configuration, occurrence, variation of properties, oxidation states, trends in chemical reactivity, anomalous properties of the first element of the group, Boron – physical and chemical properties.
Group 14 Elements: General introduction, electronic configuration, occurrence, variation of properties, oxidation states, trends in chemical reactivity, anomalous behaviour of first elements. Carbon-catenation, allotropic forms, physical and chemical properties. Phosphorus Halides
ICSE Class XII Chemistry Chapter 7 p-block elements