Write the abbreviated electron configuration for thallium. Circle the valence electrons: (4 pts) How many valence electrons does polonium have? (2 pts) How many total orbitals are in the 3d sublevel? (2 pts) Write the complete electron configuration for the Mg2+ ion. Circle the valence electrons; (4 pts)
The Correct Answer and Explanation is:
Answers:
1. Abbreviated Electron Configuration for Thallium (Tl):
Tl (Atomic Number 81):
Abbreviated configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹
Valence electrons: (6s² 6p¹) → 3 valence electrons (these are in the outermost shell)
2. How many valence electrons does Polonium (Po) have?
Po (Atomic Number 84):
Electron configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁴
Valence electrons: 6s² 6p⁴ → 6 valence electrons
3. How many total orbitals are in the 3d sublevel?
The 3d sublevel contains 5 orbitals, since each d sublevel consists of 5 orbitals (mℓ values of −2, −1, 0, +1, +2)
4. Complete Electron Configuration for Mg²⁺ (Magnesium ion):
Neutral Mg (Atomic Number 12):
Neutral: 1s² 2s² 2p⁶ 3s²
Mg²⁺ loses two electrons (from 3s orbital):
Mg²⁺: 1s² 2s² 2p⁶
Valence shell: None in outermost shell (the outermost shell is empty for Mg²⁺)
Explanation
Electron configurations describe the arrangement of electrons around an atom’s nucleus. For thallium (Tl), with atomic number 81, the abbreviated electron configuration uses the previous noble gas xenon (Xe) as a core to simplify the notation. After xenon, electrons fill the 4f, 5d, 6s, and 6p orbitals. The valence electrons in thallium are in the 6s² and 6p¹ orbitals because they are the highest principal energy level, making a total of 3 valence electrons.
For polonium (Po), which has 84 electrons, the valence electrons are those in the outermost energy level, specifically 6s² and 6p⁴. This gives polonium a total of 6 valence electrons, typical of elements in Group 16 (the oxygen family), which tend to form −2 anions due to their high electron affinity.
The 3d sublevel belongs to the third principal energy level and includes five orbitals. Each orbital can hold two electrons, giving the d sublevel a capacity of 10 electrons, but the number of orbitals remains 5. These five orbitals are labeled as 3dₓᵧ, 3dᵧ𝓏, 3d𝓏², 3dₓ𝓏, and 3dₓ²–ᵧ².
For Mg²⁺, the electron configuration begins with 1s² and continues through the 3s orbital. However, since the magnesium ion loses two electrons to form a +2 charge, these are removed from the outermost 3s orbital, leaving the configuration as 1s² 2s² 2p⁶. There are no valence electrons left in the third shell, so the ion has no valence electrons, which makes it very stable and unreactive in this form.
