{"id":23110,"date":"2022-01-17T18:48:57","date_gmt":"2022-01-17T13:18:57","guid":{"rendered":"https:\/\/infinitylearn.com\/surge\/?p=23110"},"modified":"2022-04-25T23:34:21","modified_gmt":"2022-04-25T18:04:21","slug":"the-p-block-elements-class-12-notes-chemistry-chapter-7","status":"publish","type":"post","link":"https:\/\/infinitylearn.com\/surge\/study-materials\/the-p-block-elements\/class-12\/notes-chemistry\/chapter-7\/","title":{"rendered":"The p-Block Elements Class 12 Notes Chemistry Chapter 7"},"content":{"rendered":"

I Group 15 Elements: The Nitrogen Family<\/strong><\/p>\n

1.<\/strong> In group 15 of the Periodic Table, the elements, nitrogen (7<\/sub>N), phosphorus (15<\/sub>P), arsenic (33<\/sub>As), antimony (51<\/sub>Sb) and bismuth (83<\/sub>Bi) are present.
\n2.<\/strong> (a) The elements of this group can exhibit various oxidation states ranging between -3 to+ 5.
\n(b) Maximum covalency of Nitrogen is four because it does not have d- orbitals to expand its covalence.
\n3.<\/strong> The atomic (covalent) and ionic radii (in a particular oxidation state) of the elements of the nitrogen family (group 15) are smaller than the corresponding elements of the carbon family (group 14).
\nThere is a considerable increase in covalent radius from N to P. However, from As to Bi, only a small increase is observed.
\n4.<\/strong> Nitrogen displays a great tendency to form p\u03c0-p\u03c0 multiple bonds with itself as well as with carbon and oxygen. The tendency to exhibit p\u03c0-p\u03c0 multiple bonding decreases as we move down the group.
\n5.<\/strong> Group 15 elements are more electronegative than group 14 elements. Electronegativity decreases on moving down the group from N to Bi.
\n6.<\/strong> All elements of group 15 form gaseous hydrides of the type MH3<\/sub>.
\n(\u0430) The basic strength of the hydrides decreases as we down the group. Thus, NH3<\/sub> is the strongest base.
\nNH3<\/sub> > PH3<\/sub> > ASH3<\/sub> > SbH3<\/sub>
\n(b) The thermal stability of the hydrides decreases as the atomic size increases,
\n7.<\/strong> N cannot form NX5<\/sub> because of the non-availability of d-orbitals. Bi cannot form a BiX5<\/sub> because of the reluctance of 6s electrons of Bi to participate in bond formation.
\n8.<\/strong> Nitrogen several of oxides. The rest of the members (P, As, Sb and Bi) of the group form two types of oxides: E2<\/sub>03<\/sub> and E2<\/sub>05<\/sub>.<\/p>\n

II Group 16 Elements<\/strong>
\n9.<\/strong> In group 16 of the Periodic Table, elements, oxygen (8<\/sub>O), sulphur (16<\/sub>S), selenium (34<\/sub>Se), tellurium (52<\/sub>Te) and polonium (84<\/sub>Po) are present.
\n10.<\/strong> The elements have the electronic configuration ns2np4 for their valence shells. The first element of the group 16 differs in its chemical behaviour from that of other members of the group due to its small size and high electronegativity.
\n11.<\/strong> The metallic character increases with an increase in atomic number. The first four elements are non-metallic. Non-metallic character is strongest in O and S, weaker in Se and Te while Po is metallic.
\n12.<\/strong> Atomic and ionic radii increase from top to bottom, due to an increase in the number of shells.
\n13.<\/strong> Ionisation enthalpy decreases down the group, due to an increase in size. Elements of group 16 have lower ionisation enthalpy values as compared to group 15 in the corresponding periods. This is because group 15 elements have extra stable half-filled p-orbital electronic configurations.
\n14.<\/strong> Oxygen has less negative electron gain enthalpy than sulphur due to the compact nature of the oxygen atom.
\n15.<\/strong> Next to F, O has the highest electronegativity value among the elements. Within the group, electronegativity decreases with an increase in atomic number.
\n16.<\/strong> The tendency for catenation decreases as we go down the group.
\n17.<\/strong> All the elements of the group form volatile, hydrides.
\n(a) The volatility increases from water to hydrogen sulphide and then declines.
\nThis is evident in their boiling point. Increasing order-of boiling points of hydrides is H2<\/sub>S < H2<\/sub>Se < H2<\/sub>Te < H2<\/sub>0. Down 27. the group boiling point increases because of an increase in molecular weight which increases the van der Waal\u2019s forces by 28. interaction. H2<\/sub>0 has abnormally high b.p. due to hydrogen bonding.
\n(b) The thermal stability of the hydrides decreases in the order: H2<\/sub>0>H2<\/sub>S>H2<\/sub>Se>H2<\/sub>Te>H2<\/sub>Po.
\n(c) The strength of the hydrides as acids increases in the order: H2<\/sub>0<H2<\/sub>S<H2<\/sub>Se<H2<\/sub>Te.
\n18.<\/strong> All the elements of group 16 form binary halides.
\n19.<\/strong> (a) S, Se and Te form several oxo-acids. Among the oxo-acids of S, sulphuric acid is the most important.
\n(b) Sulphurous acid (H2<\/sub>S03<\/sub>) and thiosulfiiric acid (H2<\/sub>S2<\/sub>03<\/sub>) are unstable and cannot be isolated. They exist only in aqueous solutions or in the form of their salts.<\/p>\n

III Group 17 Elements<\/strong>
\n20.<\/strong> group 17 of the Periodic Table contain fluorine (9<\/sub>F), chlorine (17<\/sub>Cl), bromine (35<\/sub>Br), iodine (53<\/sub>I) and astatine (55<\/sub>At).
\n21.<\/strong> Electronic configuration is ns2<\/sup> np5<\/sup> for valence shells.
\n22.<\/strong> Halogens have the smallest atomic radii in their respective periods due to maximum effective nuclear change.
\n23.<\/strong> The first ionisation energies are relatively high but decreases down the group. Iodine can lose an electron and form an I+<\/sup> ion.
\n24<\/strong>. Electron affinity varies as Cl > F > Br > I
\n25.<\/strong> F is the, most electronegative element known. Electronegativity decreases down the group. Halogens are good oxidising agfents. The oxidising power decreases down the group.
\n27.<\/strong> (a) Reactivity varies as F2<\/sub> > Cl2<\/sub> > Br2<\/sub> > I2<\/sub>
\n(b) Order of ionic character in M \u2013 X bond is M-F>M-Cl>M-Br>M-I
\n28.<\/strong> Strength of hydrohalic acids varies as HF<HCl<HBr<HI
\nThe order of B.P is HCl < HBr < HI < HF
\n29.<\/strong> (a) Hypohalous acids are all weak acids and exist in solution only. Acid strength decreases down the group. HOCl > HOBr > HOI
\n(b) Acid strength increases as the number of O-atoms increases for a given halogen atom. HOCl < HClO2<\/sub> < HClO3<\/sub> < HClO4<\/sub><\/p>\n

IV Group 18 Elements: The Noble Gases<\/strong>
\n30.<\/strong> In group 18 of the Periodic table, elements helium (2<\/sub>He), neon (10<\/sub>Ne), argon (18<\/sub>Ar), krypton (36<\/sub>Kr), xenon (54<\/sub>Xe) and radon (86<\/sub>Rn) are present. They are collectively called noble gases.
\n31.<\/strong> Noble gases are located at the end of each period. Their valence shell orbitals are fully occupied.
\n32.<\/strong> They are monoatomic and are sparingly soluble in water.
\n33.<\/strong> Xe forms fluorides XeF2<\/sub>, XeF4<\/sub> and XeF6<\/sub>.
\n34.<\/strong> Xe03<\/sub> is trigonal pyramidal in shape whereas XeOF4<\/sub> is square pyramidal.
\n35. Uses:<\/strong>
\n(a) He is a non-inflammable gas, lighter than air, therefore, used in filling balloons for meteorological observations.
\n(b) Ar is used to provide an inert atmosphere.<\/p>\n","protected":false},"excerpt":{"rendered":"

I Group 15 Elements: The Nitrogen Family 1. In group 15 of the Periodic Table, the elements, nitrogen (7N), phosphorus […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_focuskw":"","_yoast_wpseo_title":"The p-Block Elements Class 12 Notes Chemistry Chapter 7","_yoast_wpseo_metadesc":"CBSE Class 12 Chemistry Chapter 7 Notes: P- Block Elements. The elements from the group 13 to 18 in the periodic table are p-Block elements. They have a valence shell electronic configuration","custom_permalink":"study-materials\/the-p-block-elements\/class-12\/notes-chemistry\/chapter-7\/"},"categories":[92,27,29,21],"tags":[],"table_tags":[],"acf":[],"yoast_head":"\nThe p-Block Elements Class 12 Notes Chemistry Chapter 7<\/title>\n<meta name=\"description\" content=\"CBSE Class 12 Chemistry Chapter 7 Notes: P- Block Elements. 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