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Chapter 4 : Chemical Bonding photo_2023-09-28_13-18-09 - Coggle Diagram
Chapter 4 : Chemical Bonding
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Intramolecular Bonding
Ionic Bonds
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●The atom which donates electrons becomes positively charged (cations) and the atom which receives electrons becomes negatively charged (anions)
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●Lattice energy (LE) released must be high to formed stable ionic structures. LE is the energy released by a process in which isolated ions come together to form a crystal or ionic compound)
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Writing Lewis Structure
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•Step 4: Complete the octets of the outer atoms by distributing the remaining valence electrons in pairs.
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•Step 6: If central atom does not form an octet, form double or triple bonds .
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Dative/Coordinate Bonds
•A dative/coordinate bond is a covalent bond in which both shared/bonding electrons originate from one of the joined atoms
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•Examples: The pair of electrons that bind the N atom to another atom in the NH4+ ion and in the NH3BCl3 molecule originate from N only.
•In metal complexes such as [Cu(NH3)4]2+ the bond exist between Cu-NH3 occurred through coordinate bond. Thus the compound is known as coordination compound.
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Polar Covalent Bonds
●Polar bonds are formed when one of the elements attracts the shared electrons more strongly than the second element (These bonds are somewhere between covalent and pure ionic bonds in character)
●There is asymmetry in the distribution of electron density (the electrons being shifted towards the more electronegative atom)
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Polar Molecules
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●HCN is a polar molecule because of its asymmetric shape: the resultant polarity is enhanced towards N because it is most electronegative
Intermolecular Bonding
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Hydrogen Bonds
●The hydrogen bond is a permanent attraction which occur between molecules that contain hydrogen atom covalently bonded to small highly electronegative atoms such as N, O and F
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Bond Energy
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●It is the energy required to break one mole of gaseous molecules into their gaseous individual atoms.
●The energy is experimentally determined by measuring dissociation energy between two bonded atoms, D
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Bond Length
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●In free molecules, the size of bond length can be determined by summing the radius of two bonded atoms in the molecule.
●In solid state, the size of bond length can be determined by sum up the radius of two touched neighboring atoms in their lattice.
Bond Angle
●Is the internal angle of intersection between two lines drawn through the nucleus of a central atom from the nuclei of two atoms bonded to it.
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Resonance Structure
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○Lewis structures imply that O3 has a single (147 pm) and double (121 pm) bond, but actual bond length is between (128 pm).
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Metallic Bond
●The metallic bond consists of atoms held together by their valence electrons that are moving freely throughout the structure in 3-dimensions
●The electrons are detached from their parent atoms and are frequently referred to as an electron sea
●The atoms are held together by strong forces of attraction between the positive nuclei and the delocalised electrons
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