Ionic bonding (Explain with all types and Example) with suitable diagrams, Cheat Sheet of Medical Biochemistry

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Chemical Bonding

Atoms

Gilbert Newton Lewis

The subject of chemical bonding is at the heart of chemistry. ...

Lewis was instrumental in developing a bonding theory based on

the number of electrons in the outermost “valence” shell of the

atom

Chemical Bond:

❑ Two atoms of same or different elements approach

each other,

❑ The energy of the combination of the atoms becomes

less than the sum of the energies of the two separate

atoms at a large distance.

❑ Two atoms have combined or a bond is formed

between the two.

Quick recap

AN EFFECT THAT LEADS TO THE DECREASE IN THE ENERGY.

Bohr Model of the atom: All of the protons and the neutrons The 1 st^ ring can hold up to 2 e

- The 2nd^ **ring can hold up to 8 e

The 3 rd**^ ring can hold up to 18 e- The 4 th^ ring and any after can hold up to 32 e-

Quick recap

Quick recap

Atomic Mass = 12

Atomic Number = 6 p

= 6 , n o = 6 , e

• = 6 6 p and 6 n live in the nucleus

Hydrogen Carbon

Atomic Mass = 1 Atmoic Number = 1 p+ = 1, n o = 0, e- = 1 1 p and 0 n live in the nucleus

Ionic Bond:

NaCl

Sodium Chloride

Na + Cl Na

• Cl

2,8,1 2,8,7 2,8 2,8, Transfer of one electron from sodium atom to chlorine atom and both the atoms attain noble gas configuration.

Electrovalent or an ionic compound

Electrostatic interaction

• Octet Rule: ???

Ionic Bond:

**Electronic configuration of sodium atom (atomic number 11) is 2,8,1 (1s 2 2s 2 2p 6 3s 1 ) Highly electropositive Loses an electron Sodium cation (Na

) Na Na+**^ + e–; ∆H = 493. 8 kJ mol–^1 2 , 8 , 1 2 , 8 (∆H is enthalpy change) Electronic configuration of chlorine atom (atomic number 11) is 2,8,7 (1s 2 2s 2 2p 6 3s 2 3p 5 ) Requires one electron to Acquire the stable electronic arrangement Accept an electron Chloride anion (Cl

- ) Cl + e –^ Cl – 2 , 8 , 7 2 , 8 , 8 ∆H = – 379. 5 kJ mol - 1

Ionic compounds = a metallic cation + a nonmetallic anion

c) Dissociation of gaseous chlorine molecule into chlorine atoms Cl 2 (g) Cl(g) ; ΔH = 120.9 kJ mol

• 1 d) Conversion of gaseous chlorine atom to chloride ion (addition of electron) Cl(g) + e

Cl

(g) ; ΔH = – 379.5 kJ mol

• 1

Energetics of Ionic Compound Formation

Energetics of Ionic Compound Formation

e) Formation of NaCl from sodium and chloride ions.(Crystal or lattice formation). Na

(g) + Cl

• (g) Na + Cl - (s) ; ΔH = – 754. 8 kJ mol - 1 (Lattice energy) ❑ The net reaction would be: Na(s) + Cl 2 (g) Na

Cl - (s) ; ΔH = – 410. 9 kJ mol - 1 The overall energy change, ΔH = ( 108. 7 + 493. 8 + 120. 9 – 379. 5 – 754. 8 ) = – 410. 9 kJ mol

• 1 large decrease in the energy The approach is based on the law of conservation of energy and is known as Born-Haber cycle.

Ca

2 +

(g)

Born-Haber Cycle for CaBr