konfigurasi elektron

Summary

This video lesson for 10th-grade students focuses on the electron configuration of atoms, explaining how electrons are distributed across atomic shells according to Bohr's model and quantum mechanics. It covers how to determine electron distribution using formulas, sublevels (s, p, d, f), and the Aufbau principle, starting with atoms like sodium (Na) and calcium (Ca). The lesson also explains valence electrons and their role in determining chemical properties. The instructor provides several examples, including iron (Fe) and manganese (Mn), while highlighting special cases and common misconceptions.

Takeaways

• 🔬 Electron configuration refers to the arrangement and distribution of electrons in an atom.
• 🔢 The number of protons in an atom equals its atomic number, and for a neutral atom, the number of electrons equals the number of protons.
• 🧮 The electron shells are arranged using Bohr's model, where electrons are placed in different shells (K, L, M, N) based on the formula 2n².
• 🧪 Subshells (s, p, d, f) are part of the shells, and each can hold a specific number of electrons (2, 6, 10, 14 respectively).
• 📊 Aufbau principle states that electrons occupy subshells in order of increasing energy levels, starting from the lowest.
• ⚛️ Sodium (Na) has 11 electrons, and its configuration follows the pattern: 1s², 2s², 2p⁶, 3s¹.
• 🧱 Electron configurations can end in different subshells depending on the element's atomic structure, such as 3d for iron (Fe).
• 🔄 The last shell, or the valence shell, contains the electrons involved in chemical bonding (valence electrons).
• 🧑‍🔬 For elements like calcium (Ca), the valence shell has 2 electrons in the 4s subshell.
• ⚠️ For transition metals, such as iron (Fe), both 4s and 3d electrons are considered when determining valence electrons.

Q & A

What is electron configuration?

Electron configuration refers to the arrangement or distribution of electrons in an atom's electron shells or orbitals.

How can you determine the number of protons in an atom?

The number of protons in an atom is equal to the atomic number, which is the number of protons present in the nucleus of the atom.

For an atom of sodium (Na) with atomic number 11 and mass number 23, how many electrons and neutrons does it have?

Sodium (Na) has 11 electrons and 12 neutrons. The number of electrons is equal to the atomic number (11), and the number of neutrons is calculated by subtracting the atomic number from the mass number (23 - 11 = 12).

What formula is used to calculate the maximum number of electrons in an atomic shell?

The formula 2n² is used to calculate the maximum number of electrons in a shell, where 'n' is the shell number (or principal quantum number).

How many electrons can the first three shells (K, L, M) hold?

The K shell (n=1) can hold 2 electrons, the L shell (n=2) can hold 8 electrons, and the M shell (n=3) can hold 18 electrons.

What is the difference between the Bohr atomic model and the modern quantum mechanical model regarding electron configuration?

The Bohr model describes electrons as being arranged in distinct shells around the nucleus, whereas the quantum mechanical model introduces sub-shells (s, p, d, f) within each shell, and accounts for more complex electron behavior, including their energy levels.

What is the aufbau principle in electron configuration?

The aufbau principle states that electrons fill orbitals starting with the lowest energy levels before filling higher energy levels.

How does the sub-shell configuration of an atom differ in terms of electron capacity?

The s sub-shell can hold a maximum of 2 electrons, the p sub-shell can hold 6 electrons, the d sub-shell can hold 10 electrons, and the f sub-shell can hold 14 electrons.

What is the electron configuration for sodium (Na) using the aufbau principle?

The electron configuration for sodium (Na) is 1s² 2s² 2p⁶ 3s¹. This means sodium has 2 electrons in the 1s sub-shell, 2 in the 2s, 6 in the 2p, and 1 electron in the 3s sub-shell.

What is meant by valence electrons and how are they determined?

Valence electrons are the electrons located in the outermost shell of an atom. They are determined by the electron configuration of the atom, specifically those in the highest energy level.