Problem 104 - Chemistry The Molecular Science

Question

Name the clement corrcsponding to cach of these charactcristics. (a) The element whose atoms have the electron configura- $$ \text { tion } 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{4} $$ (b) The element in the alkaline-earth group that has the largest atomic radius (c) The element in Group \(5 \Lambda\) whose atoms have the largest first ionization energy (d) The element whose \(2+\) ion has the configuration \([\mathrm{Kr}] 4 d^{6}\) (e) The clement whose neutral atoms have the electron configuration \(\lfloor\mathrm{\Lambdar}] 3 d^{10} 4 s^{1}\)

Step-by-Step Solution

Answer

(a) Sulfur, (b) Radium, (c) Vanadium, (d) Ruthenium, (e) Copper.

Step 1: Identify Element from Electron Configuration (a)

The given electron configuration is \( 1s^2 2s^2 2p^6 3s^2 3p^4 \). This corresponds to 16 electrons, which is the atomic number of sulfur (S). Therefore, the element is sulfur.

Step 2: Determine Alkaline-Earth Element with Largest Atomic Radius (b)

The alkaline-earth metals include beryllium, magnesium, calcium, strontium, barium, and radium. As we move down the group, the atomic radius increases. Radium (Ra) is at the bottom of the group and thus has the largest atomic radius.

Step 3: Group 5 Element with Largest Ionization Energy (c)

Group 5 of the periodic table includes elements like vanadium (V), niobium (Nb), and tantalum (Ta). Ionization energy increases across a period and decreases down a group. Vanadium, being the lightest in this group, has the largest first ionization energy of the elements listed.

Step 4: Determine Element from 2+ Ion Configuration (d)

The given configuration for the ion is \([\text{Kr}] 4d^6\), which corresponds to ruthenium (Ru). Ruthenium, with an atomic number of 44, loses 2 electrons to form the \(2+\) ion with this configuration.

Step 5: Identify Element from Electron Configuration (e)

The given configuration is \([\text{Ar}] 3d^{10} 4s^1\). This corresponds to element number 29, copper (Cu), which has a characteristic configuration where the 4s orbital is singly filled to complete the 3d subshell.

Key Concepts

Electron Configuration

The electron configuration of an element tells us how electrons are distributed in its atomic orbitals. For the example of sulfur, the configuration given is \( 1s^2 2s^2 2p^6 3s^2 3p^4 \). This means sulfur has 16 electrons in total. Electrons are filled into orbitals in the order of increasing energy levels, following Hund's rule and the Pauli exclusion principle.

Understanding electron configurations helps determine an element's chemical behavior. For instance, sulfur's valence electrons make it more reactive in forming compounds like sulfides.

Atomic Radius

The atomic radius is the distance from the nucleus of an atom to the outer boundary of its electron cloud. As you move down a group in the periodic table, atomic radii increase. This is because electrons are added to new, higher energy levels, which are farther from the nucleus.

In the alkaline earth metals (Be, Mg, Ca, Sr, Ba, Ra), radium has the largest atomic radius. Its electrons are furthest from the nucleus, which affects how it bonds with other elements.

Ionization Energy

Ionization energy is the amount of energy required to remove an electron from an atom. Elements with a high ionization energy hold onto their electrons tightly. In Group 5 of the periodic table, ionization energy generally increases across a period and decreases as you move down a group.

Vanadium, being a lighter element in Group 5, exhibits a higher first ionization energy than its heavier group counterparts like tantalum and niobium. This is because the outer electrons are closer to the nucleus and more strongly attracted to it, making them harder to remove.

Alkaline Earth Metals

Alkaline earth metals are found in Group 2 of the periodic table. This group includes beryllium, magnesium, calcium, strontium, barium, and radium. They have two electrons in their outermost shell, making them fairly reactive, though less so than alkali metals.

Radium, at the bottom of this group, exhibits the largest atomic radius and is the most reactive due to its electrons being farther from the nucleus. These properties are important when considering the reactivity and bonding characteristics of these elements.