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Periodic Properties

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Topics

  • Introduction
  • Periodic Trends

Introduction:

The periodic table shows a regular pattern in the properties of elements, known as periodic trends. These trends are observed in valency, atomic size, and metallic-nonmetallic character across periods (horizontal rows) and groups (vertical columns).

Structure of the Periodic Table:

  • 18 groups (columns): Elements in the same group have the same number of valence electrons, giving them similar chemical properties.
  • 7 periods (rows): Elements in the same period have the same number of electron shells but different valence electrons.

Periodic Trends:

1. Valency

  • Valency depends on the number of electrons in the outermost shell.
  • Elements in the same group have the same valency (e.g., Li, Na, and K have 1 valence electron).

2. Atomic Size

  • Across a period (left to right): Atomic size decreases due to increasing nuclear charge pulling electrons closer.
  • Down a group: Atomic size increases as new electron shells are added.

3. Metallic and Nonmetallic Character

  • Metals (left side) lose electrons easily and have lower valency.
  • Nonmetals (right side) gain electrons to complete their valence shell.
  • Across a period: Metallic character decreases, nonmetallic character increases.
  • Down a group: Metallic character increases, nonmetallic character decreases.
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Video Tutorials

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Shaalaa.com | Periodic Classification of Elements part 7 (Trends in periods 1)

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Periodic Classification of Elements part 7 (Trends in periods 1) [00:10:37]
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