Problem 6 - Chemistry and Chemical Reactivity

Question

Using spdfand noble gas notations, write electron configurations for atoms of the following elements and then check your answers with Table 8.3. (a) Strontium, Sr. This element is named for a town in Scotland. (b) Zirconium, Zr. The metal is exceptionally resistant to corrosion and so has important industrial applications. Moon rocks show a surprisingly high zirconium content compared with rocks on earth. (c) Rhodium, Rh. This metal is used in jewelry and in catalysts in industry. (d) Tin, Sn. The metal was used in the ancient world. Alloys of tin (solder, bronze, and pewter) are important.

Step-by-Step Solution

Answer

Strontium: [Kr] 5s^2, Zirconium: [Kr] 5s^2 4d^2, Rhodium: [Kr] 5s^2 4d^7, Tin: [Kr] 5s^2 4d^{10} 5p^2.

Step 1: Understanding Strontium (Sr) Electron Configuration

Strontium has an atomic number of 38. In standard electron configuration notation, this means we need to place 38 electrons around the nucleus. Using noble gas notation, we find the nearest noble gas with a lower atomic number, then add additional electrons to account for the difference. The nearest noble gas to Sr is Krypton (Kr), which has an atomic number of 36.

Step 2: Writing Electron Configuration for Strontium

After recognizing that Krypton (Kr) accounts for 36 electrons, write the electron configuration from there. 1. Account for the next 2 electrons: they fill the 5s orbital.Thus, the electron configuration is: \[ \text{[Kr]} \, 5s^2 \]

Step 3: Understanding Zirconium (Zr) Electron Configuration

Zirconium has an atomic number of 40. Again, we start with the nearest noble gas, Krypton (Kr), with an atomic number of 36.

Step 4: Writing Electron Configuration for Zirconium

Following Krypton's configuration, add electrons:1. Add 2 electrons to the 5s orbital.2. Next, add 2 electrons to the 4d orbital.Thus, the electron configuration is: \[ \text{[Kr]} \, 5s^2 \, 4d^2 \]

Step 5: Understanding Rhodium (Rh) Electron Configuration

Rhodium has an atomic number of 45. Start with the nearest noble gas configuration, Krypton (Kr), which is 36 electrons.

Step 6: Writing Electron Configuration for Rhodium

After Krypton, distribute the remaining electrons:1. Add 2 electrons to the 5s orbital (5s^2).2. Then, add 7 electrons to the 4d orbital (4d^7).Thus, the electron configuration is: \[ \text{[Kr]} \, 5s^2 \, 4d^7 \]

Step 7: Understanding Tin (Sn) Electron Configuration

Tin has an atomic number of 50. Starting with the nearest noble gas, Krypton, which has 36 electrons, proceed to fill the remaining electrons.

Step 8: Writing Electron Configuration for Tin

From Krypton:1. Add 2 electrons to the 5s orbital (5s^2).2. Fill 10 electrons in the 4d orbitals (4d^{10}).3. Finally, add 2 electrons to the 5p orbital (5p^2).Thus, the electron configuration is:\[ \text{[Kr]} \, 5s^2 \, 4d^{10} \, 5p^2 \]

Key Concepts

spdf notation

The spdf notation is a method used to describe the electron configuration of an atom. It helps us understand how electrons are distributed in various orbitals around the nucleus. Each letter (s, p, d, f) corresponds to a specific type of orbital, and the numbers indicate how many electrons are in each. For example:

• s: Can hold up to 2 electrons
• p: Can hold up to 6 electrons
• d: Can hold up to 10 electrons
• f: Can hold up to 14 electrons

Each orbital has a particular energy level, and the electrons fill these orbitals starting from the lowest energy level. This notation is essential for understanding the arrangement of electrons in different elements, like Strontium and Zirconium.

noble gas notation

Noble gas notation is a shorthand method of writing electron configurations. It simplifies the process by using the electron configuration of the nearest noble gas as a reference point. This is useful because noble gases have full outer electron shells, which are very stable.
For example, Strontium (Sr) uses Krypton (Kr) as a reference, leaving only the outer electrons to consider. Thus, instead of writing a long string of numbers and letters, we can write \[ \text{[Kr]} \, 5s^2 \] where [Kr] indicates the configuration up to Krypton, and 5s indicates the remaining electrons. This method is not only concise but also clarifies the additional electrons that distinguish an element from its predecessor in the periodic table.

atomic number

The atomic number of an atom tells us the number of protons in its nucleus, which also equals the number of electrons in a neutral atom. It's vital for determining the electron configuration because it lets us know exactly how many electrons we have to arrange.
Each element on the periodic table has a unique atomic number. For instance:

• Strontium (Sr): Atomic number 38
• Zirconium (Zr): Atomic number 40
• Rhodium (Rh): Atomic number 45
• Tin (Sn): Atomic number 50

Knowing the atomic number is the first step in writing an element's electron configuration because it guides everything that follows. It's like the backbone of the atom's identity.

electron orbitals

Electron orbitals are regions around the nucleus of an atom where electrons are likely to be found. These orbitals have different shapes (spherical, dumbbell, etc.) and are grouped into various energy levels. Understanding orbitals is key to explaining an electron's behavior around a nucleus.
The four types of orbitals—denoted as s, p, d, and f—have unique properties:

• The s orbital is spherical and closest to the nucleus.
• The p orbitals have a dumbbell shape and are oriented in different directions (x, y, z).
• The d orbitals are more complex, with a cloverleaf shape, and are filled after the s and p orbitals of the same energy level.
• The f orbitals are even more intricate and are filled with higher energy elements.

Recognizing how these orbitals fill with electrons allows us to predict an element's chemical properties and reactions.