Ch 03 - Classification of Elements and Periodicity in Properties11th Chemistry
Historical Discovery of Elements
How many elements were known in the year 1800 compared to 1865?
How many elements were known in the year 1800 compared to 1865?
In 1800, only 31 elements were known. By 1865, the number of identified elements had more than doubled to 63 elements.
Prism Memory Hook
1800 has 31 (half of 63), 1865 has 63.
Dobereiner's Law of Triads
What is Dobereiner's Law of Triads (1829), and what are the three classic elemental triad examples?
What is Dobereiner's Law of Triads (1829), and what are the three classic elemental triad examples?
Statement: In certain groups of three elements (triads) with similar properties, the atomic weight of the middle element is approximately the average of the atomic weights of the other two.
Examples:
- Lithium (), Sodium (), Potassium ()
- Calcium (), Strontium (), Barium ()
- Chlorine (), Bromine (), Iodine ()
Prism Memory Hook
LiNaK, CaSrBa, ClBrI
Newlands' Law of Octaves
State Newlands' Law of Octaves (1865) and identify its major limitations.
State Newlands' Law of Octaves (1865) and identify its major limitations.
Statement: When elements are arranged in increasing order of their atomic weights, every eighth element has properties similar to the first element (like musical octaves).
Limitations:
- It seemed to be true only up to Calcium ().
- The later discovery of Noble Gases disrupted the entire octave arrangement.
Prism Memory Hook
Octaves stop at Calcium; Noble gases break the rhythm.
Also in this chapter
39 more cards to study in Prism
- 4Lothar Meyer's Periodicity Curve
- 5Mendeleev's Periodic Law
- 6Mendeleev's Undiscovered Elements
- 7Moseley's X-Ray Frequency Law
- 8Mendeleev's Anomalous Pairs
- 9Modern Periodic Law
- 10IUPAC Nomenclature Roots (0-9)
- 11IUPAC Name: Atomic Number 120
- 12Significance of Periods
- 13Number of Elements in the 6th Period
- 14The s-Block Elements
- 15The p-Block Elements
- 16The d-Block (Transition) Elements
- 17Exceptions in the d-Block Elements
- 18The f-Block (Inner-Transition) Elements
- 19Lanthanoids vs. Actinoids
- 20Transuranium Elements
- 21Metals vs. Non-Metals: Periodic Trends
- 22Metalloids (Semi-Metals)
- 23The Anomalous Position of Hydrogen
- 24The Position of Helium
- 25Chalcogens and Halogens
- 26Trends in Atomic Radius
- 27Cation vs. Anion Size
- 28Radius of Isoelectronic Species
- 29First Ionization Enthalpy ($\Delta_i H$)
- 30Ionization Enthalpy Anomaly: Be vs B
- 31Ionization Enthalpy Anomaly: N vs O
- 32Electron Gain Enthalpy ($\Delta_{eg} H$)
- 33Positive EGE of Noble Gases
- 34EGE Anomaly: O/F vs S/Cl
- 35Second Electron Gain Enthalpy of Oxygen
- 36Electronegativity (EN) and the Pauling Scale
- 37Periodicity of Valency (Oxidation States)
- 38Anomalous Properties of Second Period Elements
- 39Diagonal Relationship
- 40Acid-Base Nature of Element Oxides
- 41Covalency Expansion Limitation
- 42Origin of the Pauling Scale
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