1s Orbital

Definition

The 1s orbital is the innermost and lowest-energy orbital in an atom, occupied by the first electron in the atom's electron configuration. It is a spherical orbital with a single lobe and no angular momentum, making it the simplest and most stable of all atomic orbitals.

5 Must Know Facts For Your Next Test

1. The 1s orbital has a principal quantum number of 1, which means it is the closest orbital to the nucleus and has the lowest energy level.
2. The 1s orbital has an angular momentum quantum number (l) of 0, indicating that it has no angular momentum and is a spherical orbital.
3. The 1s orbital can only hold a maximum of 2 electrons, as dictated by the Pauli exclusion principle.
4. The 1s orbital is the first orbital to be filled in the electron configuration of an atom, and it is completely filled in the noble gas configuration.
5. The 1s orbital plays a crucial role in the sp2 hybridization of carbon atoms, which is the basis for the structure of ethylene.

Review Questions

• Explain how the 1s orbital is involved in the sp2 hybridization of carbon atoms.
  • In the sp2 hybridization of carbon atoms, the 1s orbital of the carbon atom combines with two of its 2p orbitals to form three equivalent sp2 hybrid orbitals. These sp2 hybrid orbitals are oriented in a trigonal planar arrangement, with bond angles of approximately 120 degrees. The remaining 2p orbital, which is perpendicular to the plane of the sp2 hybrid orbitals, forms a pi (π) bond with another carbon atom, as seen in the structure of ethylene (C2H4).
• Describe the key characteristics of the 1s orbital that make it the most stable and simplest of all atomic orbitals.
  • The 1s orbital is the most stable and simplest of all atomic orbitals due to several key characteristics. Firstly, it has a principal quantum number of 1, which means it is the closest orbital to the nucleus and has the lowest energy level. Secondly, it has an angular momentum quantum number (l) of 0, indicating that it has no angular momentum and is a perfectly spherical orbital. This lack of angular momentum contributes to its high stability. Additionally, the 1s orbital can only hold a maximum of 2 electrons, as dictated by the Pauli exclusion principle, further enhancing its stability.
• Analyze the role of the 1s orbital in the electron configuration of an atom and its relationship to the noble gas configuration.
  • The 1s orbital plays a fundamental role in the electron configuration of an atom, as it is the first orbital to be filled in the electron configuration. The 1s orbital is completely filled in the noble gas configuration, which represents the most stable arrangement of electrons in an atom. This is because the noble gas configuration, with a full 1s orbital, has a very low energy and is highly stable. The 1s orbital's contribution to the overall stability of the noble gas configuration highlights its importance in determining the chemical properties and behavior of atoms.

Related terms

Electron Configuration: The arrangement of electrons in an atom's orbitals, which determines the atom's chemical properties and behavior.

Atomic Orbitals: The mathematical functions that describe the wave-like behavior of an electron in an atom and the regions of space where the electron is likely to be found.

Quantum Numbers: A set of integers that uniquely define the state of an electron in an atom, including its energy level, angular momentum, and orientation in space.