Study Guides/Chemistry/1 to 30 Elements With Symbols & Electronic Configuration
Study Guide · Chemistry

Elements 1 to 30: Symbols and Electronic Configuration

Knowing the first 30 elements of the periodic table, along with their symbols and electronic configurations, is fundamental for chemistry students. The electronic configuration describes how electrons are distributed in the atomic orbitals of an element.

Question (Click to Flip)

Why does Chromium have an anomalous electronic configuration?

Answer

Chromium has the configuration [Ar] 3d5 4s1 instead of [Ar] 3d4 4s2 because a half-filled d-orbital (d5) is more stable than a partially filled one. An electron shifts from the 4s orbital to the 3d orbital to achieve this stability.

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Key Facts

Chromium (24) and Copper (29) are exceptions to the Aufbau principle due to the stability of half-filled and fully-filled d-orbitals.

Noble gases (He, Ne, Ar) are often used in brackets to represent the core electrons.

Elements 21 to 30 belong to the 3d transition metal series.

1. Elements 1 to 10

  1. Hydrogen (H): $1s^1$
  2. Helium (He): $1s^2$
  3. Lithium (Li): $[He] 2s^1$
  4. Beryllium (Be): $[He] 2s^2$
  5. Boron (B): $[He] 2s^2 2p^1$
  6. Carbon (C): $[He] 2s^2 2p^2$
  7. Nitrogen (N): $[He] 2s^2 2p^3$
  8. Oxygen (O): $[He] 2s^2 2p^4$
  9. Fluorine (F): $[He] 2s^2 2p^5$
  10. Neon (Ne): $[He] 2s^2 2p^6$

2. Elements 11 to 20

  1. Sodium (Na): $[Ne] 3s^1$
  2. Magnesium (Mg): $[Ne] 3s^2$
  3. Aluminum (Al): $[Ne] 3s^2 3p^1$
  4. Silicon (Si): $[Ne] 3s^2 3p^2$
  5. Phosphorus (P): $[Ne] 3s^2 3p^3$
  6. Sulfur (S): $[Ne] 3s^2 3p^4$
  7. Chlorine (Cl): $[Ne] 3s^2 3p^5$
  8. Argon (Ar): $[Ne] 3s^2 3p^6$
  9. Potassium (K): $[Ar] 4s^1$
  10. Calcium (Ca): $[Ar] 4s^2$

3. Elements 21 to 30

  1. Scandium (Sc): $[Ar] 3d^1 4s^2$
  2. Titanium (Ti): $[Ar] 3d^2 4s^2$
  3. Vanadium (V): $[Ar] 3d^3 4s^2$
  4. Chromium (Cr): $[Ar] 3d^5 4s^1$ (Exception)
  5. Manganese (Mn): $[Ar] 3d^5 4s^2$
  6. Iron (Fe): $[Ar] 3d^6 4s^2$
  7. Cobalt (Co): $[Ar] 3d^7 4s^2$
  8. Nickel (Ni): $[Ar] 3d^8 4s^2$
  9. Copper (Cu): $[Ar] 3d^{10} 4s^1$ (Exception)
  10. Zinc (Zn): $[Ar] 3d^{10} 4s^2$

Questions and Answers

Why does Chromium have an anomalous electronic configuration?+

Chromium has the configuration [Ar] 3d5 4s1 instead of [Ar] 3d4 4s2 because a half-filled d-orbital (d5) is more stable than a partially filled one. An electron shifts from the 4s orbital to the 3d orbital to achieve this stability.

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