Chemistry Formulas for Chemical Bonding

Chemistry Formulas for Chemical Bonding

 

   1.       Necessary condition for an ionic solid to be dissolved in water

                                Hydration Energy > Lattice Energy

   2.       Order of melting and boiling points of certain compounds

NaF > NaCl > NaBr > NaI;    MgO > CaO > BaO

3.       No Bond is 100% Ionic

4.       Force of attraction between two oppositely charged ions in vacuum (air) as per Coulombs Law

F = q₁q₂/r²

5.       Order of the Lattice Energy of some compounds

·         LiX > NaX > KX > RbX > CsX    (where X = F, Cl, Br, I)

·         MgO > CaO > SrO > BaO

·         MgCO₃ > CaCO₃ > SrCO₃ > BaCO₃

·         BaSO₄ > SrSO₄ > CaSO₄ > MgSO₄  

·         Mg(OH)₂ > Ca(OH)₂ > Sr(OH)₂ > Ba(OH)₂

·         Bivalent Ions-Bivalent Ions > Univalent Ions-Bivalent Ions or Bivalent Ions-Univalent Ions > Univalent Ions- Univalent Ions

6.       Example of some compounds which contains more than one type of bond

·         NaOH, KOH, Na₂CO₃  (Ionic Bond, Covalent Bond)

·         CO, NH₃.BF₃, [Co(NH₃)₃Cl₃]  (Dative Bond, Covalent Bond)

·         NH₄Cl, CuSO₄, K₄[Fe(CN)₆], [Cu(NH₃)₄]SO₄  (Dative Bond, Ionic Bond, Covalent Bond)

·         CuSO₄.5H₂O  (Hydrogen Bond, Dative Bond, Ionic Bond, Covalent Bond)

7.       Double bond or triple bond is always shorter than corresponding single bond

8.       As S-Orbital is smaller than P-Orbital so bond length decrease with increase in S-character

SP³  C-H  =  1.093 Å (as in Alkanes)

SP²  C-H  =  1.087 Å (as in Alkenes)

SP  C-H  =  1.057 Å (as in Alkynes)

9.       Bond length increases if size of bonded atom is increases with given atom

HI > HBr > HCl > HF

10.   Bond distance is directly proportional to Atomic size

11.   Order of bond strength (or bond energy) of different hydrogen halides

H-F > H-Cl > H-Br > H-I

12.   Bond energy is directly proportional to bond order

Triple Bond > Double Bond > Single Bond

13.   Formula of Dipole Moment

Dipole moment (µ) = Electronic Charge (e) x Distance (d)

14.   Unit of Dipole Moment

Debye (D)

1D = 1 x 10^-18e.s.u. cm

SI unit of Dipole Moment is = Coulomb-Meter (C-m)

1D = 3.336 x 10^-30 C-m

15.   Dipole Moment of some substances

Substance with Formula	Dipole Moment (D)
HF	1.91
H2O	1.84
SO2	1.60
NH3	1.46
NF3	0.24
CH3Cl	1.86
HCl	1.03
H2S	1.10
HBr	0.78
HI	0.38

16.   Formula to calculate percentage ionic character of covalent bond

% Ionic Character = (Observed dipole moment x 100)/Dipole moment for 100% ionic bond

17.   Order of polarizing power of cations

Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺

Be²⁺ > Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺

Al³⁺ > Mg²⁺ > Na⁺

18.   Order of polarizing power of anions

N^3- > O^2- > F^-

P^3- > S^2- > Cl^-

19.   Chemistry Formula of Bond Order

Bond Order = [N_b-N_a]/2

Where,

                N_a = Number of electrons in antibonding molecular orbitals

                N_b = Number of electrons in bonding molecular orbitals

20.   Some molecules with their bond order, bond length and bond dissociation energy

Molecule	Bond Order	Bond Length (pm)	Bond Dissociation Energy (kJ/mol)
F2	1	142	158
O2	2	121	498
N2	3	110	945

21.   Bond Order in compounds which exhibits Resonance

Bond Order = (Total No. of bonds between two atoms)/(Total No. of resonating structures)