Inorganic Chemistry Formula Sheet & Key Concepts - IIT-JEE MAINS 2027

Welcome to the ultimate LibreTexts-style chapter breakdown for IIT-JEE MAINS 2027 Inorganic Chemistry. This guide synthesizes key theoretical frameworks, essential equations, and periodic trends designed to maximize your score under the latest NTA testing patterns.

1. Atomic Structure & Periodic Trends

Mastering atomic properties relies on evaluating electron shielding and charge distribution. The effective nuclear charge represents the net positive charge experienced by an electron in a multi-electron atom.

Effective Nuclear Charge (\(Z_{\text{eff}}\))

The core relation is given by:

\[Z_{\text{eff}} = Z - S\]

where \(Z\) is the atomic number and \(S\) is the screening/shielding constant evaluated via Slater's Rules.

Slater's Rules for Shielding Constant (\(S\))

• For electrons in the same \((ns, np)\) group: contribution is \(0.35\) each (except \(1s\) which contributes \(0.30\)).
• For electrons in the \((n-1)\) shell: contribution is \(0.85\) each.
• For electrons in \((n-2)\) or lower shells: contribution is \(1.00\) each.

Periodic Trends Overview

• Atomic Radius: Decreases across a period (\(\to\)), Increases down a group (\(\downarrow\)).
• Ionization Energy (IE): Increases across a period (\(\to\)), Decreases down a group (\(\downarrow\)).
• Electron Affinity (EA): Increases/becomes more negative across a period (\(\to\)), Decreases down a group (\(\downarrow\)).
• Electronegativity (EN): Increases across a period (\(\to\)), Decreases down a group (\(\downarrow\)).

2. Chemical Bonding & VSEPR Theory

Understanding electron distribution in polyatomic species enables exact predictions of molecular geometry, polarity, and reactivity.

Formal Charge

The formal charge (\(\text{FC}\)) of an atom in a Lewis structure is determined by:

\[\text{FC} = V - N - \frac{B}{2}\]

where \(V\) = total valence electrons in the free atom, \(N\) = number of non-bonding electrons, and \(B\) = number of bonding electrons.

Molecular Orbital (MO) Theory - Bond Order

\[\text{Bond Order} = \frac{N_b - N_a}{2}\]

where \(N_b\) is the number of electrons in bonding molecular orbitals and \(N_a\) is the number of electrons in antibonding molecular orbitals.

VSEPR Geometries by Steric Number

• Steric Number 2: Linear (ideal bond angle: \(180^\circ\))
• Steric Number 3: Trigonal Planar (ideal bond angle: \(120^\circ\))
• Steric Number 4: Tetrahedral (ideal bond angle: \(109.5^\circ\))
• Steric Number 5: Trigonal Bipyramidal (ideal bond angles: \(90^\circ, 120^\circ\))
• Steric Number 6: Octahedral (ideal bond angle: \(90^\circ\))

Consider the structure of sulfur hexafluoride as an example of octahedral geometry (steric number 6):

```smiles FS(F)(F)(F)(F)F ```

3. Coordination Chemistry

Coordination compounds play a crucial role in IIT-JEE MAINS inorganic questions, specifically covering Crystal Field Theory (CFT), magnetic behavior, and isomerism.

Crystal Field Stabilization Energy (CFSE)

For an octahedral complex, CFSE is calculated as:

\[\text{CFSE} = \bigl(-0.4 n_{t_{2g}} + 0.6 n_{e_g}\bigr) \Delta_o + \text{P.E.}\]

where \(n_{t_{2g}}\) and \(n_{e_g}\) are electron populations in the respective orbital sets, \(\Delta_o\) is the octahedral splitting energy, and \(\text{P.E.}\) represents pairing energy.

Spin-Only Magnetic Moment

\[\mu = \sqrt{n(n+2)}\text{ BM}\]

where \(n\) is the number of unpaired d-electrons.

Isomerism Classification

• Structural Isomerism: Ionization, Hydrate, Linkage, Coordination, and Polymerization isomerism.
• Stereoisomerism: Geometrical (\(cis/trans\), \(fac/mer\)) and Optical (\(d\) and \(l\) enantiomers).

4. Acids, Bases & Solvents

Acids and bases are governed by complementary theoretical frameworks:

• Hard Soft Acid Base (HSAB) Principle: Hard acids prefer binding to hard bases (forming predominant ionic bonds), whereas soft acids prefer soft bases (forming predominant covalent complexes).
• Br\(\varnothing\)nsted-Lowry Theory: Acid = proton (\(H^+\)) donor; Base = proton (\(H^+\)) acceptor.
• Lewis Acid-Base Concept: Acid = electron pair acceptor; Base = electron pair donor.

An exemplary acid-base neutralization producing a carbon oxide is shown by: \(CH_4 + 2O_2 \to CO_2 + 2H_2O\).

5. Organometallics & Catalysis

The 18-Electron Rule

Transition metal organometallic complexes achieve chemical stability when their total valence electron count equals 18:

\[\text{Total Valence Electrons} = \text{Metal valence electrons} + \text{Ligand electron contribution}\]

Key Industrial Catalytic Processes

• Hydroformylation (Oxo Process): Synthesis of aldehydes from alkenes using cobalt or rhodium catalysts.
• Wacker Process: Oxidation of ethylene to acetaldehyde via \(PdCl_2\) and \(CuCl_2\) catalysts.
• Ziegler-Natta Polymerization: Production of stereospecific polyalkenes using \(TiCl_4\) and \(Al(C_2H_5)_3\).

6. PYQ Analysis & NTA Weightage Pattern

Based on recent trends established by the National Testing Agency (NTA) for IIT-JEE MAINS, Inorganic Chemistry accounts for approximately 30-33% of the total chemistry weightage. Master structural concepts, VSEPR configurations, and CFSE calculations, as over 1 Lakh PYQs repeatedly emphasize these core formulas.

7. Frequently Asked Questions (People Also Ask)