Periodic Table Formulas

Periodic Table is a chart of all the known elements. Get acquainted with the symbols and full names of all the elements in it easily by referring to our Periodic Table Formula Collection. Be strong with the fundamentals of the Periodic Table Concept by accessing our Periodic Table Cheat Sheet. As you start practicing the formulas you will recall them easily along with the names of chemical compounds.

1. Mendeleev’s periodic table was based upon atomic weight & Modern Periodic table is based upon atomic no.

2. General electronic configuration (of outer orbits):

• s-block ⇒ ns^1-2
• p-block ⇒ ns²np^1-6
• d-block ⇒ (n – 1)d^1-10ns^1-2,
• f-block ⇒ (n – 2) f^1-14 s² p⁶ d¹⁰ (n – 1) s²p⁶d^{0 or 1}ns²

3. Calculation of covalent radius:

• In A₂, r_A = d_A-A/2
• In AB, d_A-B = r_A + r_B (If X_A ≈ X_B)
• Sh comaker & Stevenson formula, d_A-B = r_A + r_B – 0.09 Δx (if X_A ≠ X_B)

4. VWR > MR > CR & Size of isoelectronic Species Z ↑ r ↓

5.

6. (a) Scale of EN:

(b) X_m = 2.8 x_p, x_p = 0.349 x_AR + .744, √x_p = 0.2 x_s + 0.77 SR
⇒ Stability Ratios

7. % ionic character = 16 Δ + 3.5 Δ² = 16(x_A – x_B) + 3.5 (x_A – x_B)²
(Henny & Smyth formula)

8.

9. (i) Radius:

• In Pr (r)_max = Inert gas element (VWR)
• r ↓ r almost same → r ↑
  
• Radius of members of 4d & 5d series is almost same r (Lanthanide Contraction)

(ii) Ionisation Potential (IP):
Unit of I.P. = KJ mole^-1, eV & 1 eV = 96.5 KJ mol^-1 & IP₁ < IP₂ < IP₃ < IP₄ …….
If ΔIP ≥ 16 eV then lower oxidation state is stable. & If ΔIP ≤ 11.2 eV then higher oxidation state is stable.
IP ∝ \(\frac{1}{\text { size }} \propto \frac{1}{\text { Screening effect }} \propto \frac{1}{\text { no. of innerelectrons }}\) ∝ nuclear
charge ∝ Stability
(Stability) ⇒ p⁶ > d¹⁰ > p³ > d⁵ & (IP) p⁶ > d¹⁰ > p³ > d⁵
& (IP) 2^nd transition series > 3^rd transition series.
(IP) He > Li & Tl > In & Pb > Sn & Zn > Ga & w < Zn
& N > O, P > S & Be > B, Mg > Al & First IP of Al = First IP of Ga
IP ∝ \(\frac{1}{\text { Metallic character }} \propto \frac{1}{\text { Re ducing character }} \propto \frac{1}{\text { Reactivity }}\)
\(\propto \frac{1}{\text { Basic Nuture of oxide }} \propto \frac{1}{\text { Basic Nuture of hydroxide }}\)

(iii) Electron Affinity (EA):
EA ∝ \(\frac{1}{\text { size }}\) ∝ nuclear charge
(EA) N < C < P < Si & EA of IA, IIA & 0 group elements = 0
EA of II period elements < EA of Bonding III period element eg. F < Cl

(iv) (X or EN):
(EN ∝ nuclear attraction ∝ + ye oxidation state ∝ \(\frac{1}{\text { atomicradius }}\) ∝ % S character). (energy) sp > sp² > sp³ & (EN) sp > sp² > sp³
& (Size) sp < sp² < sp³
(EN of hybrid) CH ≡ CH > CH₂ = CH₂ > CH₃ – CH₃
& (acidic nature) CH ≡ CH > CH₂ = CH₂ > CH₃ – CH₃
(EN) ⇒ Cation > atom, anion < atom
cr⁺⁶ > cr⁺³ > cr⁺², F^– < F
c^⊕ > c > c^⊖
(EN) ⇒ Si < P < C < N,
H ≤ P
Δ EN ∝ B.E. ∝ \(\frac{1}{\text { Bond Length }}\) ∝ % ionic character ∝ non metallic
character ∝ BS
EN of inert gas = 0
In 4d & 5d series on moving in the same group EN ↑

10. Some important Points:

• Heaviest of Most Dense Metal = Os
• Hardest metal or Max MP = W
• Artificially made Radio Active elements = ₄₃Tc, ₆₁Pm
• Semimetal elements ⇒ B, Si, As, Te, At
• Density ⇒ Na > K, Mg > Ca (Exception)
• Chalcogen family ⇒ O, S, Se, Te, Po (oxygen family)
• Density order ⇒ f-block element > d > p > s
• Diagonal relationship ⇒ (I) Li & Mg (II) Be & A1 (III) B & Si

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