Third Row d-Block (5d Series) — Periodic Table Mnemonic
Target: mnemonic for 5d transition metals third row d block
Why is this hard to memorize?
The 5d series runs from Lanthanum to Mercury (with Lanthanides inserted between La and Hf). For JEE purposes, the key elements are La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg. This series includes some of the densest metals (Os, Ir), the most corrosion-resistant (Pt, Au), and elements with the highest melting points (W at 3422°C). Questions on lanthanide contraction effects on 5d elements, catalytic activity of Platinum-group metals, and mercury's liquid state at room temperature are JEE favourites.
Classic mnemonics you should know
"Lady Hates Tantrums — Wears Real Ornaments: Iridescent Platinum, Authentic Gold, Hg(Mercury) drops"
La(Lady) → Lanthanum, Hf(Hates) → Hafnium, Ta(Tantrums) → Tantalum, W(Wears) → Tungsten, Re(Real) → Rhenium, Os(Ornaments) → Osmium, Ir(Iridescent) → Iridium, Pt(Platinum) → Platinum, Au(Authentic) → Gold, Hg(Hg) → Mercury.
"La Hf Ta W Re Os Ir Pt Au Hg — "LAHT Wren Oscar I Patch Gold Mercury""
Chunked for rhythm: La-Hf-Ta(LAHT), W-Re(Wren), Os(Oscar), Ir(I), Pt(Patch), Au(Gold), Hg(Mercury).
"Lazy Hafiz Talks Wildly, Revealing Osmosis Irish Platinum Gold Hg plans"
Each word starts with or sounds like the element symbol. The story about a talkative person helps visualization.
The complete list
- Lanthanum (La)
- Hafnium (Hf)
- Tantalum (Ta)
- Tungsten (W)
- Rhenium (Re)
- Osmium (Os)
- Iridium (Ir)
- Platinum (Pt)
- Gold (Au)
- Mercury (Hg)
Frequently asked questions
Is the 5d series important for NEET?
NEET focuses mainly on 3d. But 5d elements like Pt (catalyst), Au (chemistry of gold), and Hg (only liquid metal) appear in application-based questions. JEE Advanced tests 5d series more seriously.
What is the lanthanide contraction and how does it affect 5d elements?
The gradual decrease in atomic radius across the 4f lanthanide series means that 5d elements (Hf onwards) are almost the same size as their 4d counterparts (Hf ≈ Zr, Ta ≈ Nb). This leads to similar chemistry between 4d and 5d pairs.
Why is Mercury a liquid at room temperature?
Mercury has a [Xe]4f¹⁴5d¹⁰6s² configuration. The 6s² electrons are held very tightly (relativistic contraction), weakening metallic bonding. Hg–Hg bonds are so weak that Mercury exists as individual atoms in the liquid state.
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