Introduction to Darmstadtium (Ds)
Darmstadtium (Ds) is a synthetic chemical element with atomic number 110. It belongs to the family of superheavy elements and is classified as a transactinide element, meaning it comes after the actinide series in the periodic table. Darmstadtium is not found naturally on Earth; it is created in laboratories by bombarding heavy atomic nuclei with lighter ones. It is named after Darmstadt, Germany, where it was first synthesized at the Gesellschaft für Schwerionenforschung (GSI) in 1994. All known isotopes of Darmstadtium are extremely unstable, decaying rapidly within seconds or even milliseconds. This extreme instability makes its study particularly challenging.
Atomic Structure Fundamentals of Darmstadtium
The atomic structure of Darmstadtium, like any element, is defined by the number of subatomic particles: protons, neutrons, and electrons.
Number of Protons, Neutrons, and Electrons
- Protons: The atomic number (Z) of Darmstadtium is 110. This directly indicates that every atom of Darmstadtium contains 110 protons in its nucleus. The number of protons determines the element’s identity.
- Electrons: In a neutral atom, the number of electrons is equal to the number of protons. Therefore, a neutral Darmstadtium atom contains 110 electrons, which orbit the nucleus.
- Neutrons: The number of neutrons can vary for different isotopes of an element. Since Darmstadtium is synthetic and has many known isotopes, the neutron count depends on the specific isotope being considered. For example, one of the more stable isotopes is Darmstadtium-281 ($^{281}$Ds), which has a mass number (A) of 281. The number of neutrons is calculated as A - Z.
- Number of neutrons = Mass Number - Atomic Number
- Number of neutrons = 281 - 110 = 171 neutrons (for $^{281}$Ds). Other isotopes would have different numbers of neutrons.
Electron Configuration of Darmstadtium
The electron configuration describes the arrangement of electrons in the atomic orbitals around the nucleus. For Darmstadtium (110 electrons), the configuration follows the Aufbau principle, Hund’s rule, and the Pauli exclusion principle.
Deriving the Electron Configuration
Given its atomic number 110, Darmstadtium is located in Period 7 and Group 10 of the periodic table. Its electron configuration can be written by starting from the noble gas core of the preceding period (Radon, [Rn], which has 86 electrons) and then filling the subsequent orbitals in order of increasing energy:
The full electron configuration for Darmstadtium is: $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^6 7s^2 5f^{14} 6d^8$
This can be written in a condensed form using the noble gas core of Radon (Rn) (atomic number 86): $[Rn] 5f^{14} 6d^8 7s^2$
It should be noted that for very heavy, superheavy elements like Darmstadtium, relativistic effects become significant and can lead to deviations from the predicted Aufbau principle filling order. However, for high school level understanding, the configuration derived from the general rules as shown above is standard.
Valence Electrons
Valence electrons are the electrons located in the outermost shell of an atom, which are involved in chemical bonding. For transition metals, including Darmstadtium, the valence electrons typically include those in the outermost s-subshell and the partially filled or completely filled d-subshell of the principal quantum number immediately below the outermost s-shell.
Based on the electron configuration $[Rn] 5f^{14} 6d^8 7s^2$:
- The outermost s-orbital is $7s^2$.
- The $6d^8$ electrons also contribute to the valence shell due to their proximity in energy and involvement in bonding.
Therefore, Darmstadtium possesses 10 valence electrons ($6d^8 + 7s^2$).