Back to Science
⚗️
🧪 Chemistry
Periodic Table
Mendeleev's 1869 arrangement of all 118 elements by atomic number; the map of matter
Russia 🇷🇺 1869 Chemistry
Key Facts
- 1
Dmitri Mendeleev (1869) arranged 63 known elements by atomic mass; predicted 3 missing ones
- 2
Modern table ordered by atomic number (protons); 118 elements confirmed; 94 occur naturally
- 3
Periods (rows): electron shells; Groups (columns): similar chemical properties; Noble gases (Group 18) are inert
🔬 Did you know? Mendeleev left gaps in his table for undiscovered elements and predicted their properties — all three (gallium, scandium, germanium) were found within 15 years
Quick Reference
Category
Chemistry
Country
🇷🇺 Russia
Year / Era
1869
About
Mendeleev's 1869 arrangement of all 118 elements by atomic number