Interactive Periodic Table of 118 Elements
Full 18-column IUPAC standard grid with real-time property heatmaps, secondary and higher secondary examination presets (Z=1 to 30), Latin name etymology, Aufbau principle exceptions, and curriculum quiz.
Hydrogen
(হাইড্রোজেন)Periodic Table Mnemonics & Group Shortcuts
High-yield mnemonic sentences to effortlessly recall elements by group for competitive and board examinations:
Group 1 (Alkali Metals)
H, Li, Na, K, Rb, Cs, Fr"Little Nasty Kids Rub Cats' Fur"
Group 2 (Alkaline Earth)
Be, Mg, Ca, Sr, Ba, Ra"Beer Mugs Can Serve Bar Rats"
Group 13 (Boron Family)
B, Al, Ga, In, Tl"Bears Always Get In Trouble"
Group 14 (Carbon Family)
C, Si, Ge, Sn, Pb"Can Simple Germans Snore Loudly?"
Group 15 (Pnictogens)
N, P, As, Sb, Bi"Never Put Arsenic in Submarines or Boats"
Group 17 (Halogens)
F, Cl, Br, I, At"First Class Biryani In Australia"
Latin Origins & Variable Valency Reference Table
Chemical symbols derived from Latin root names with their common and variable valency states:
| Common Name | Symbol | Latin Origin | Atomic No. (Z) | Valency States | Nomenclature Suffixes |
|---|---|---|---|---|---|
| Sodium | Na | Natrium | 11 | 1 | Fixed +1 oxidation state |
| Potassium | K | Kalium | 19 | 1 | Fixed +1 oxidation state |
| Iron | Fe | Ferrum | 26 | 2, 3 | Ferrous (+2), Ferric (+3) |
| Copper | Cu | Cuprum | 29 | 1, 2 | Cuprous (+1), Cupric (+2) |
| Silver | Ag | Argentum | 47 | 1 | Argentous (+1) |
| Tin | Sn | Stannum | 50 | 2, 4 | Stannous (+2), Stannic (+4) |
| Antimony | Sb | Stibium | 51 | 3, 5 | Antimonous (+3), Antimonic (+5) |
| Tungsten | W | Wolfram | 74 | 2, 4, 6 | High melting point (3422°C) |
| Gold | Au | Aurum | 79 | 1, 3 | Aurous (+1), Auric (+3) |
| Mercury | Hg | Hydrargyrum | 80 | 1, 2 | Mercurous (+1), Mercuric (+2) |
| Lead | Pb | Plumbum | 82 | 2, 4 | Plumbous (+2), Plumbic (+4) |
Periodic Trends & Critical Examination Anomalies
Key physical and chemical trends across periods and down groups, plus textbook anomalies tested in entrance exams:
1. Atomic Radius
Decreases across a period left-to-right because nuclear charge increases while valence electrons enter the same principal quantum shell, pulling the electron cloud tighter.
2. 1st Ionization Energy Anomalies
Increases across a period generally, but subshell stability causes two notable exceptions:
- • Be (899 kJ) > B (801 kJ) [Be has filled 2s²]
- • N (1402 kJ) > O (1314 kJ) [N has half-filled 2p³]
3. Electron Affinity (Cl vs F)
Usually increases towards the top-right. However, Chlorine's electron affinity exceeds Fluorine's:
Due to intense inter-electronic repulsion within Fluorine's extremely crowded 2p subshell.
★ Aufbau Anomalies: The Half-Filled / Fully-Filled Rule
The heightened exchange energy of half-filled ($d^5$) and fully-filled ($d^10$) configurations overrides the Aufbau n+l ordering:
Expected: [Ar] 3d⁴ 4s²
Observed: [Ar] 3d⁵ 4s¹
Expected: [Ar] 3d⁹ 4s²
Observed: [Ar] 3d¹⁰ 4s¹
Frequently Asked Questions About the Periodic Table
Q1.How many elements, periods, and groups are in the periodic table?
The modern IUPAC periodic table consists of 118 confirmed chemical elements organized into 7 horizontal rows (periods) and 18 vertical columns (groups). Elements 1 (Hydrogen) to 94 (Plutonium) occur naturally, while elements 95 to 118 are synthetic.
Q2.Why do Chromium (Cr) and Copper (Cu) violate the Aufbau principle?
Subshells that are exactly half-filled (d⁵) or completely filled (d¹⁰) gain anomalous stability due to spatial symmetry and maximized exchange energy. Chromium promotes a 4s electron to form [Ar] 3d⁵ 4s¹ instead of [Ar] 3d⁴ 4s², and Copper forms [Ar] 3d¹⁰ 4s¹ instead of [Ar] 3d⁹ 4s².
Q3.Why is the electron affinity of Chlorine greater than Fluorine?
Fluorine's valence electrons occupy a very compact 2p subshell with high electron charge density. When an extra electron approaches, strong inter-electronic repulsion weakens the net attraction. Chlorine's larger 3p subshell accommodates the incoming electron with less repulsion, giving Chlorine (-349 kJ/mol) a higher electron affinity than Fluorine (-328 kJ/mol).
Q4.Which elements exist as liquids at room temperature (STP)?
Under standard temperature and pressure (STP, 25°C, 1 atm), only two elements are liquids: Mercury (Hg, a transition metal) and Bromine (Br, a halogen). Gallium (Ga) and Cesium (Cs) melt slightly above room temperature (29.8°C and 28.4°C).
Q5.Which element has the highest electronegativity?
Fluorine (F) holds the highest electronegativity value on the Pauling scale at 3.98 (commonly approximated as 4.0), making it the most aggressively electron-withdrawing element in chemical bonding.