Konfigurasi Elektron Subkulit || Materi Kimia SMA || Kelas X || Hikmah nor

Main Ideas

• Subshell electron configuration, also called spdf configuration, shows how an atom’s electrons occupy subshells.

• Under the Aufbau principle, electrons fill lower-energy subshells before higher-energy ones. The order does not simply mean “finish one shell, then move to the next.” Instead, follow the diagonal or “zigzag” order, such as: [ 1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d \rightarrow 4p \rightarrow 5s ]

• Each subshell has a maximum electron capacity:

  • s: 2 electrons
  • p: 6 electrons
  • d: 10 electrons
  • f: 14 electrons
• The final subshell may be only partly filled. For example, sodium ends in (3s^1), and manganese ends in (3d^5).
• Shell notation groups electrons by principal shell, while subshell notation gives the more detailed (s,p,d,f) arrangement. For a neutral atom, the total number of electrons in the configuration should equal its atomic number.

Examples

Sodium (Na), atomic number 11

• Full configuration: (1s^2\,2s^2\,2p^6\,3s^1)
• Noble-gas shorthand: ([Ne]\,3s^1)
• Shell distribution: 2, 8, 1

Calcium (Ca), atomic number 20

• Full configuration: (1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,4s^2)
• Noble-gas shorthand: ([Ar]\,4s^2)

Manganese (Mn), atomic number 25

• Full configuration: (1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,4s^2\,3d^5)
• Noble-gas shorthand: ([Ar]\,4s^2\,3d^5)

Noble-Gas Shorthand Method

1. Find the noble gas immediately before the element.
2. Replace the configuration up through that noble gas with its symbol in brackets.
3. Add the remaining subshells, following the filling order.
4. Check that the total number of electrons matches the element’s atomic number.

The video gives these noble gases and atomic numbers as reference points: helium (2), neon (10), argon (18), krypton (36), xenon (54), and radon (86).

Speakers and Sources

• Instructor/narrator: The subtitles do not name the speaker. The title credits Hikmah Nor.
• Channel: Happy Chemistry