Chemistry UNIT 1 PDF

## UNIT-II CHEMICAL BONDING In this branch of chemistry we study about **Chemistry** **Chemical bonds** which forms between two atoms. There are some reasons for bond formation: - to obtain octet or duplet - to gain stability - to gain inertness ### *Covalent Bonding* - When two or more than two...

## UNIT-II CHEMICAL BONDING In this branch of chemistry we study about **Chemistry** **Chemical bonds** which forms between two atoms. There are some reasons for bond formation: - to obtain octet or duplet - to gain stability - to gain inertness ### *Covalent Bonding* - When two or more than two atoms Share their electrons to complete their octet or duplet then this type of bonding is called covalent bond. - eg. - H, He - **duplet** - rest all - **octet** ### #There are total 118 elements in the periodic table: - **S**: 2 - **P**: 6 - **d**: 10 - **f**: 14 | Shell no. | | |---|---| | n=1 | S | | n=2 | S, p | | n=3 | s, p, d | | n=4 | s, p, d, f | - eg. - **Hydrogen**(H) = 1s¹ - **Fluorine**(F) = 1s², 2s², 2p⁵ - **Phosphorous**(P) = 1s², 2s², 2p⁶, 3s², 3p³ ### Chemical Bonding - eg. - **H₂ molecule** - H-O-H OR H-H - **NH₃ (Ammonia)** - H - \ \ N / H O- H - OR H-N-H - **H₂O (water)** - H - O - H - OR H-O-H ### *Ionic Bonding* - In ionic bonding one atom transfer its one or more electrons to other atom. In this case electrostatic force of attraction occur between atoms. - eg. - **Na (11)** → 2, 8, 1 - **Cl (17)** → 2, 8, 7 - **Na⁺** → 2, 8 - **Cl⁻** → 2, 8, 8 - **Ionic compounds are strong in nature.** - **Ionic compounds are soluble in nature.** - eg. - **Mg (12)** → 2, 8, 2 - **Cl (17)** → 2, 8, 7 - **Cl (17)** → 2, 8, 7 - **Mg²⁺** → 2, 8 - **Cl⁻** → 2, 8, 8 - **Cl⁻** → 2, 8, 8 - "Electrostatic force of attraction" - eg. - **Al (13)** → 2, 8, 3 - **Cl (17)** → 2, 8, 7 - **Cl (17)** → 2, 8, 7 - **Cl (17)** → 2, 8, 7 - **Al³⁺** → 2, 8 - **Cl⁻** → 2, 8, 8 - **Cl⁻** → 2, 8, 8 - **Cl⁻** → 2, 8, 8 ### *Coordinate Bonding* - In this type of bonding one atom donate its lone pair to another atom. - Coordinate bond is represented by (→). - eg. - **(NH₄)⁺ ion** - H - \ \ N / H O- H - OR H-N-→H - **(H₂O)⁺ ion** - H - O - H - OR H-O-→H ### *Hybridisation* - In this process two or more than two atomic orbitals of singular energy intermix and form new hybrid orbitals of same energy. - This process is known as **Hybridisation**. - There are many types of hybridisation: - **sp** - sp¹d - **sp²** - sp³d² - **sp³** - sp³d³ - **Sp Hybridisation** - when one S and one P atomic orbitals combine together they form new sp hybridized orbitals. - eg. - **Central atom (min. no.)** = Be(4) = 1s², 2s², 2p² - **Surrounding atom** = F(9) - H and F can never be central atom. - In Hybridisation only outermost shell involve. - **Be** = 1l - 2s = l l - 2p = l l - For Hybridisation, the no. of unpaired electron at central atom should equal to no. of surrounding atom. - **F** = 2s - 2p = 1l 1l 1l - 2s = 1l 1l - 1l - 1l - σ bond - **Be** = 1l - 2p = 1l 1l - **F** = 1l 1l 1l - 1l 1l 1l 1l 1l - Only sigma bond (σ) considered in hybridisation. - In BeF₂, S and P orbital of Be is used in hybridisation. - Structure of sp Hybridisation = Linear = 180° bond angle. - eg. - **BeCl₂** - FBe-F - 180° - Cl-Be-Cl - 180° - **U** = 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l - **Be** = 1l - 2p = 1l 1l - **Cl** = 1l 1l 1l - 1l 1l 1l 1l 1l ### **Sp² Hybridisation** - In this Hybridisation one S orbital and two p orbitals intermix together to form sp² hybridised orbitals. - eg. - **BF₃** {B(5), F(9)} - **B** = 1l - 2s² = 1l 1l - **F** = 1l 1l 1l - 2s² = 1l 1l 1l - **F** = 1l 1l 1l - 2s² = 1l 1l 1l - **F** = 1l 1l 1l - 2s² = 1l 1l 1l - The Structure of sp² hybridisation is **trigonal planar**. - The bond angle in sp² hybridisation is **120°**. ### **Sp³ Hybridisation** - In this Hybridisation one S orbital and three P orbitals intermix together to form sp³ hybridised orbitals. - eg. - **CH₄** - **C** = 1l - 2s² = 1l 1l - 2p² = 1l 1l 1l 1l - **C** = 1l - 2s² = 1l 1l - 2p² = 1l 1l 1l 1l - **H** = 1l - 1s = 1l - **H** = 1l - 1s = 1l - **C** = 1l - 2s² = 1l 1l - 2p² = 1l 1l 1l 1l - **H** = 1l - 1s = 1l - **H** = 1l - 1s = 1l - The Structure of sp³ hybridisation is tetrahedral and bond angle is **109.28°**. ### **Sp³d Hybridisation** - In this hybridisation, one S orbital and three P orbital and one d orbital intermix together to form sp³d hybridised orbitals of same energy. - eg. - **PCl₅ & PF₅** - **P(15)** = 1s², 2s², 2p⁶, 3s², 3p³, 3d - **P** = 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l - **P** = 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l 1l 1l - **F(9)** - The Structure of sp³d is **Trigonals bi-pyramidle** ### **Sp³d² Hybridisation** - In this hybridisation, one S orbital and three P orbital and one d orbital intermix together to form sp³d² hybridised orbitals of same energy. - eg. - **SF₆** - **S(16)** - 1s² 2s² 2p⁶ 3s² 3p⁴ - **S** = 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l - **S** = 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l 1l 1l - **F(9)** - **F** - **F** - **F** - **F** - **F** - **F** - The structure of sp³d² is **Octahedral** . ### **Sp³d³ Hybridisation** - In this Hybridisation one S and three P orbitals and three D orbitals intermix. together to form sp³d³ Hybridisation - eg. - **IF₇** - **I(53)** = 5s², 5p⁵, 5d⁰ - **I** = 1l - 5s = 1l 1l 1l - 5p = 1l 1l 1l 1l 1l - 5d = 1l 1l 1l 1l 1l - **I** = 1l 1l - 5s = 1l 1l 1l - 5p = 1l 1l 1l 1l 1l - 5d = 1l 1l 1l 1l 1l - **F** - **F** - **F** - **F** - **F** - **F** - **F** - The Structure of sp³d³ is **pentagonal bi-pyramide** * **Valence Shell Electron Pair Repulsion Theory (VSEPR)** This theory is given by **Nhylom and Glasphi** - According to this theory, there are some rules for the prediction of the structure of compounds. - **The Geometry of molecules depends on the bond pairs and lone pairs.** - **If molecule have all bond pair, then it have regular gometry.** - **If lone pair is present, then it will have distorted structure with lower bond angle.** - **Lone pair repel lone pair and bond pair which decrease the bond angle** - **Lone pair should be present at that position which have maximum space.** - The order of repulsion is: **LP-LP > LP-BP > BP-BP**. ### Examples - **CH₄** - **C(6)** = 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **C** = 1l 1l 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l 1l - **H(1)** = 1l - 1s = 1l - **H** = 1l - 1s = 1l - **H** = 1l - 1s = 1l - **H** = 1l - 1s = 1l - Structure. ( diagram shows 4 H atoms bonded to a central C atom with angles of 109 degree) - **NH₃** - **N(7)** - 1l 1l 1l - 2s 2p - **N** = 1l 1l 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **H(1) ** - **H** - **H** - Structure - (diagram shows 3 H atoms bonded to a central N atom and a lone pair on the top of the N atom. The angles are 107 degree and 120 degree.) - **H₂O** - **O(8)** (sp³ Hybridization) - 1l 1l 1l 1l - 2s 2p - **O** = 1l 1l 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **H** - **H** - Structure - (diagram shows 2 H atoms bonded to a central O atom and 2 long pairs on top of the O atom. The angle is 105 degree) - **SF₄** - **S(16)** - 2, 8, 6 - **S** = 1l 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l - **S** = 1l 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l 1l 1l - **F** - **F** - **F** - **F** - **Hybridisation sp³d** - Geometry: **Trigonals bipyramedal** - Shape: **See-Saw** - **SCl₃F** - **Cl(17)** - 1l 1l 1l 1l - 3s 3p - 3d - **Cl** = 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l 1l - **Cl** = 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l 1l 1l - **F** - **F** - **F** - **Sp³d Hybridisation** - Geometry: **torgonal bipyram** - Shape: **T Shape** - **ICl₂** - **I(53)** - 5s², 5p³, - **I** = 5s², 5p², 5d⁰ - 5s = 1l 1l 1l 1l - 5p = 1l 1l 1l 1l 1l - 5d = 1l 1l 1l 1l - **I** = 1l 1l 1l - 5s = 1l 1l 1l - 5p = 1l 1l 1l 1l 1l - 5d = 1l 1l 1l - **Cl** - **Cl** - **Sp³d Hybridisation** - Geometry: **torgonal bipyramidle** - Shape: **linear** - **NH₄⁺** - **N(7)** = 1s², 2s², 2p³, N⁺ = 2s², 2p² - **N** = 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **N** = 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **H** - **H** - **H** - **H ** - **sp³ Hybridisation** - Geometry: **Tetrahedral** - Shape: - **TeF₅** - **Te(52)** = 5s², 5p⁴, 5d¹ - **Te** = 1l 1l 1l - 5s = 1l 1l - 5p = 1l 1l 1l 1l - 5d = 1l 1l 1l - **Te** = 1l 1l 1l 1l - 5s = 1l 1l 1l - 5p = 1l 1l 1l 1l - 5d = 1l 1l 1l - **Te** = 1l 1l 1l 1l 1l - 5s = 1l 1l 1l - 5p = 1l 1l 1l 1l - 5d = 1l 1l 1l 1l - **F** - **F** - **F** - **F** - **F** - **Sp³d² Hybridisation** - Geometry: **Octahydral** - Shape: **square pyramidal** - In Hybridisation only σ bond takes part. - π bonds not considered in Hybridisation. - Oxygen form double bond. - Nitrogen form triple bond. ### **CO₂** - **C** = 1s², 2s², 2p² - **C** = 1l 1l - 2s = 1l 1l - 2p = 1l 1l - **C** = 1l 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **O** = 1s², 2s², 2p⁴ - **O** = 1l 1l 1l - **O** = 1l 1l 1l - **σ bond** - **σ bond** - **π bond** - **Sp hybridisation** - **linear** = **180°** - **O=C=O** ### **SO₂** - **S** = 1s², 2s², 2p⁶, 3s², 3p⁴ - **S** = 1l 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l - **S** = 1l 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l - 3d = 1l - **O** - **O** - **sp² hybridisation** = **trigonal planar** ### **SO₃** - **S=1s² 2s² 2p⁶ 3s² 3p⁴** - **S** = 1l 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l - **S** = 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l - 3d = 1l - **O** - **O** - **O** - **sp² hybridisation** = **trigonal planar** ### **SO₄²⁻** - **S=1s², 2s², 2p⁶, 3s², 3p⁴** - **S** = 1l 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l - **O** - **O** - **O** - **O** - **sp³ Hybridisation** - **tetrahedral** ### **CO₃²⁻** - **C** = 1s², 2s², 2p² - **C** = 1l 1l - 2s = 1l 1l - 2p = 1l 1l - **C** = 1l 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **O** - **O** - **O** - **sp² hybridisation** - **trigonal planar** ### **NO₃⁻** - **N** = 1s², 2s², 2p³ - **N** = 1l 1l 1l 1l - 2s = 1l 1l - 2p = 1l 1l 1l - **O** - **O** - **O** - **sp² hybridisation** - **trigonal planar** ### **PO₄³⁻** - **P(15)** = 1s², 2s², 2p⁶, 3s², 3p³, 3d⁰ - **P** = 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l 1l 1l - **P** = 1l 1l 1l 1l - 3s = 1l 1l 1l - 3p = 1l 1l 1l 1l - 3d = 1l 1l 1l 1l - **O** - **O** - **O** - **O** - **sp³ Hybridisation** - **tetrahedral** ### **Cl₂O₇** - **Cl** = 1s², 2s², 2p⁶, 3s², 3p⁵ - **Cl** = 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l 1l - **Cl** = 1l 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l - 3d = 1l - **O** - **O** - **O** - **O** - **O** - **O** - **O** - **Cl** = 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l 1l - 3d = 1l 1l 1l - **Cl** = 1l 1l 1l - 3s = 1l 1l - 3p = 1l 1l - 3d = 1l 1l - **sp³ Hybridisation** - **tetrahedral** * **Resonance** Sometimes, it is not possible to explain all the properties of a compound with a single structure and we need more than one structure to explain chemical and physical property of a compound. When a compound shows more than one structure then this is known as resonance. - **Resonance = shifting of negative charge/ π bond take place.** - **example**: **benzene** - ( diagram shows a hexagonal ring with alternating single and double bonds ) - **NO₃⁻** - ( diagram shows a NO₃⁻ molecule with a single bond on one oxygen atom and two double bonds to the other oxygen atoms, and the negative charge rotates between all 3 oxygen atoms) - **CO₃²⁻** - ( diagram shows a CO₃²⁻ molecule with alternating single and double bonds with the negative charges rotating between all 3 oxygen atoms) - **PO₄³⁻** - ( diagram shows a PO₄³⁻ molecule with alternating single and double bonds with the negative charges rotating between all 4 oxygen atoms) - **SO₄²⁻** - ( diagram shows a SO₄²⁻ molecule with alternating single and double bonds with the negative charges rotating between all 4 oxygen atoms) - **Aniline** - ( diagram shows aniline with a benzene ring and an NH₂ group, the charges rotate between N and O at the other end of the benzene ring) - **Chloro benzene** - ( diagram shows a benzene ring with a chlorine atom on one end, the charges rotate between N and O at the other end of the benzene ring) - **Nitro benzene** - ( diagram shows a benzene ring with a nitro group on one end, the charges rotate between N and O at the other end of the benzene ring) - **Resonance is also known as conjugation.** * **Hyperconjugation** It is advanced form of conjugation. - In this process sigma bond take part. - For this conjugation α-H & present should be present next to **carbokation or double bond.** - This resonance is also known as **no-bond resonance.** - **eg.** - (diagram shows 2 carbons bonded to 3 hydrogen atoms, the positive charge rotates between the last two carbons) - ( diagram shows 4 carbons bonded to hydrogen atoms. The first and last carbons have single bonds to hydrogen and the second and third carbons have double bonds to hydrogen) - ( diagram shows 4 carbons bonded to hydrogen atoms where the positive charge rotates between the second and third carbons) - ( diagram shows 4 carbons bonded to hydrogen atoms where the positive charge rotates between the third and fourth carbons)