Chemistry · Class 11 · Chapter 3
Classification of Elements and Periodicity in Properties
13 lessons119 min5 simulations10 practice questions
This chapter traces how chemists sorted the elements, from Dobereiner's triads and Newlands' octaves to Mendeleev's table and the modern long form built on atomic number. It then reads the table through electronic configuration (periods, groups and the s, p, d, f blocks) and explains the periodic trends in atomic and ionic size, ionization enthalpy, electron gain enthalpy, electronegativity, valence and reactivity.
Also called: periodic table · periodic properties · periodic trends
Lessons
13 lessons · 119 min
01Why classify, and the first attemptsNCERT §3.1, §3.27 min02Mendeleev's periodic tableNCERT §3.27 min03Modern periodic law and the long formNCERT §3.37 min04Naming elements with Z above 100NCERT §3.46 min05Electronic configuration, periods and groupsNCERT §3.57 min06The s, p, d and f blocksNCERT §3.6.1-3.6.411 min1 sim07Metals, non-metals and metalloidsNCERT §3.6.57 min08Atomic and ionic radiiNCERT §3.7.1(a), (b)15 min2 sims09Ionization enthalpyNCERT §3.7.1(c)11 min1 sim10Electron gain enthalpy and electronegativityNCERT §3.7.1(d), (e)11 min1 sim11Valence and the anomalous second periodNCERT §3.7.28 min12Periodic trends and chemical reactivityNCERT §3.7.37 min13Chapter reviewMust-know facts, traps and formulas15 min
Simulations
5 in this chapter
From configuration to place in the tableIn: The s, p, d and f blocksHow big is an atom?In: Atomic and ionic radiiTen electrons, a growing nucleusIn: Atomic and ionic radiiPulling an electron offIn: Ionization enthalpyWhich atom welcomes an extra electron?In: Electron gain enthalpy and electronegativity