Understanding the Long Form Electron Configuration of Technetium (Tc)Technetium is a unique element with atomic number 43 and chemical symbol Tc. It is the first artificially produced element and holds a special position in the periodic table as a transition metal. One of the fundamental aspects of understanding any element’s chemical nature is analyzing its electron configuration. This topic explores the long form electron configuration of technetium, how it’s derived, and what it reveals about the element’s properties.
What Is Electron Configuration?
Electron configuration refers to the specific arrangement of electrons in an atom’s orbitals. These configurations are important in predicting how atoms interact in chemical reactions. The rules governing electron configuration include
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The Aufbau principle electrons fill orbitals starting from the lowest energy levels.
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Hund’s rule each orbital in a subshell gets one electron before any gets two.
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Pauli exclusion principle no two electrons in the same atom can have identical quantum numbers.
These principles help build the electron configurations for each element.
General Information About Technetium
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Symbol Tc
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Atomic number 43
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Group 7 (transition metals)
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Period 5
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Block d-block
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State at room temperature Solid
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Radioactive Yes (no stable isotopes)
Technetium is often used in nuclear medicine for imaging and diagnostics, particularly the isotope technetium-99m.
How to Write the Long Form Electron Configuration of Technetium
To determine the long form electron configuration of technetium, we need to account for its 43 electrons and place them in the appropriate orbitals.
Following the order of orbital filling
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁵
This is the complete long form electron configuration of technetium.
Step-by-Step Breakdown of the Configuration
Let’s break down how we arrive at this configuration
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1s² 2s² 2p⁶ These orbitals cover the first and second energy levels, accounting for the first 10 electrons.
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3s² 3p⁶ The third shell is filled with the next 8 electrons, taking us to 18 electrons.
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4s² 3d¹⁰ 4p⁶ This sequence adds 18 more electrons, totaling 36.
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5s² Two electrons go into the 5s orbital, reaching 38 electrons.
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4d⁵ The remaining five electrons enter the 4d subshell, resulting in the final electron count of 43.
Thus, technetium’s electron configuration ends in 4d⁵.
Noble Gas Notation for Reference
The shorthand electron configuration or noble gas notation uses the previous noble gas to simplify the expression
[Kr] 5s² 4d⁵
Here, [Kr] represents the electron configuration of krypton (atomic number 36). This condensed form is often used in chemical equations or when discussing valence electrons, but for detailed understanding, the long form provides greater clarity.
Valence Electrons and Chemical Properties
Technetium’s valence electrons are located in the 5s and 4d orbitals. These outer electrons determine how the element bonds with others and explain its position among the transition metals.
With five electrons in the 4d subshell, technetium shows a variety of oxidation states, ranging from +1 to +7, although +7 is the most common in compounds like technetium(VII) oxide.
Technetium’s Place in the Periodic Table
Technetium is located in
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Group 7 alongside manganese (Mn), rhenium (Re), and bohrium (Bh)
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Period 5 fifth row of the periodic table
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d-block elements with electrons filling d orbitals
Being the first element without a stable isotope, technetium marks a turning point in the periodic table where radioactivity begins to appear even in relatively light elements.
Importance of 4d Orbitals
The 4d orbitals play a crucial role in defining the chemistry of technetium. Compared to its group neighbor manganese (which has a 3d⁵ configuration), technetium’s 4d⁵ configuration gives it similar but subtly distinct properties due to the increased size and energy of the 4d orbitals.
This also contributes to the element’s complex bonding behavior and ability to form coordination compounds.
Real-World Uses of Technetium
Though technetium itself is radioactive and not found in nature in significant quantities, it has important applications, especially in
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Medical imaging Technetium-99m is used in over 80% of nuclear diagnostic procedures.
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Corrosion resistance When alloyed with steel, technetium can inhibit corrosion.
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Chemical research Its unique oxidation states make it useful in coordination chemistry studies.
Understanding its electron configuration helps explain its chemical reactivity and behavior in these applications.
Comparing Technetium with Its Neighbors
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Manganese (Mn, atomic number 25) 3d⁵ 4s²
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Rhenium (Re, atomic number 75) 5d⁵ 6s²
All three elements have a d⁵ configuration, although in different energy levels (3d, 4d, 5d). This suggests that the Group 7 elements tend to favor half-filled d subshells, which offer enhanced stability.
Summary Table Technetium’s Electron Configuration
| Property | Value |
|---|---|
| Atomic number | 43 |
| Symbol | Tc |
| Long form configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁵ |
| Shorthand configuration | [Kr] 5s² 4d⁵ |
| Valence electrons | 5s² 4d⁵ |
| Common oxidation states | +7, +5, +4 |
The long form electron configuration of technetium, 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁵, provides essential insight into the structure and chemical nature of this rare and radioactive transition metal. By understanding how its electrons are arranged, we can appreciate its unique behavior, versatile oxidation states, and its invaluable role in modern technology and medicine.
Whether for students, educators, or professionals in science, grasping technetium’s electron configuration is a key step in exploring the periodic table and the world of atomic structure.