The p-block elements are located in groups 13 to 18 of the periodic table. Their valence shell electronic configuration is ns2np1−6 (except Helium, which has 1s2). The properties of p-block elements are significantly influenced by factors such as atomic size, 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) also play a crucial role in determining their properties.
Group 15 includes nitrogen, phosphorus, arsenic, antimony, and bismuth. As we move down the group, the elements exhibit a gradual shift from non-metallic to metallic character. Nitrogen and phosphorus are non-metals, arsenic and antimony are metalloids, and bismuth is a metal. Nitrogen makes up about 78% of the Earth's atmosphere by volume, while phosphorus is found in minerals such as fluorapatite.
Property | N | P | As | Sb | Bi |
---|---|---|---|---|---|
Atomic number | 7 | 15 | 33 | 51 | 83 |
Atomic mass (g/mol) | 14.01 | 30.97 | 74.92 | 121.75 | 208.98 |
Electron configuration | [He]2s22p3 | [Ne]3s23p3 | [Ar]3d104s24p3 | [Kr]4d105s25p3 | [Xe]4f145d106s26p3 |
Ionisation enthalpy (kJ/mol) | 1402 | 1012 | 947 | 834 | 703 |
Electronegativity | 3.0 | 2.1 | 2.0 | 1.9 | 1.9 |
Covalent radius (pm) | 70 | 110 | 121 | 141 | 148 |
Ionic radius (pm) | 171 | 212 | 222 | 76 | 103 |
Melting point (K) | 63 | 317 | 1089 | 904 | 544 |
Boiling point (K) | 77.2 | 554 | 888 | 1860 | 1837 |
Density (g/cm^3 at 298 K) | 0.879 | 1.823 | 5.778 | 6.697 | 9.808 |
The common oxidation states for Group 15 elements are -3, +3, and +5. The tendency to exhibit -3 oxidation state decreases down the group due to increased size and metallic character. Conversely, the stability of the +5 oxidation state decreases, and the +3 state becomes more stable due to the inert pair effect.
All Group 15 elements form hydrides of the type EH3 (E = N, P, As, Sb, Bi). The stability of these hydrides decreases from NH3 to BiH3.
Group 15 elements form two types of oxides: E2O3 and E2O5. The acidic character of these oxides decreases down the group.
These elements react with halogens to form two series of halides: EX3 and EX5. Nitrogen does not form pentahalides due to the absence of d-orbitals.
Did You Know? Nitrogen exhibits a maximum covalency of 4 due to the availability of only four orbitals (one s and three p) for bonding, unlike the heavier elements that can expand their covalency by using d orbitals.
NEET Tip: Focus on the Haber process conditions (pressure, temperature, and catalysts) as they are frequently asked in NEET.
Answers:
Common Misconception: Students often confuse the stability of the oxidation states in Group 15 elements. Remember that the stability of the +3 oxidation state increases down the group due to the inert pair effect.
Concept Connection: Relate the properties of Group 15 elements with their position in the periodic table and their electron configurations.
Group 16 elements include oxygen, sulfur, selenium, tellurium, and polonium. These elements are known as chalcogens. The valence shell electronic configuration is ns2np4.
The atomic and ionic radii increase from oxygen to polonium due to the addition of extra electron shells.
Ionisation enthalpy decreases down the group due to the increase in atomic size.
Electronegativity decreases down the group, with oxygen being the most electronegative element.
The melting and boiling points increase with an increase in atomic number. Oxygen and sulfur are non-metals, selenium and tellurium are metalloids, and polonium is a metal.
Did You Know? Oxygen forms 46.6% by mass of the Earth's crust, making it the most abundant element on Earth.
The elements exhibit oxidation states of -2, +2, +4, and +6. The stability of the +6 oxidation state decreases down the group, while the +4 state becomes more stable.
Group 16 elements form hydrides of the type H2E (E = O, S, Se, Te, Po). The acidic character of these hydrides increases from H2O to