Problem 12 - Chemistry The Central Science In Si Units

Question

State where in the periodic table these elements appear: (a) elements with the valence-shell electron configuration \(n s^{2} n p^{5}\) (b) elements that have three unpaired \(p\) electrons (c) an element whose valence electrons are \(4 s^{2} 4 p^{1}\) (d) the \(d\) -block elements [Section 6.9 ]

Step-by-Step Solution

Answer

(a) Group 17; (b) Group 15; (c) Group 13 (Gallium); (d) Groups 3-12 (transition metals).

Step 1: Identify elements in Group 17

Elements with the valence-shell electron configuration \( n s^{2} n p^{5} \) are located in Group 17 of the periodic table. These are the halogens, which include elements like fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are one electron short of having a full valence shell.

Step 2: Identify elements with three unpaired p electrons

Elements that have three unpaired \( p \) electrons, indicated by the configuration \( n p^{3} \), are located in Group 15 of the periodic table. This group consists of the nitrogen group elements, such as nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). Each of these elements has three half-filled \( p \) orbitals.

Step 3: Find the element with valence configuration 4s2 4p1

The element with valence electrons \( 4s^2 4p^1 \) is Gallium (Ga). This electron configuration places it in Group 13 of the periodic table, as it falls under the p-block consisting of main group elements.

Step 4: Identify d-block elements

The \( d \)-block elements are located in Groups 3 to 12 of the periodic table. These are also known as transition metals and include elements such as scandium (Sc), titanium (Ti), iron (Fe), nickel (Ni), and copper (Cu). They are characterized by the filling of \( d \) orbitals.

Key Concepts

Valence Shell Electron Configuration

Valence shell electron configuration is a key concept when studying the periodic table as it helps determine the chemical properties and reactions of an element. The valence shell is the outermost shell of an atom and holds the electrons that participate in bonding.

• An electron configuration like \(n s^{2} n p^{5}\) indicates that the outer shell has two electrons in the s orbital, followed by five electrons in the p orbital.
• This configuration is typical for the Group 17 elements, known as the halogens.

For example, chlorine (Cl) has the electron configuration [Ne] 3s² 3p⁵, making it a member of this group.
Understanding these configurations helps scientists predict how elements will interact with others, primarily because the valence electrons are the ones involved in forming bonds.

Halogens

Halogens are a fascinating group of elements located in Group 17 of the periodic table. These elements are known for being highly reactive, primarily because they are only one electron short of having a complete valence shell.
Key characteristics of halogens include:

• High electronegativity, meaning they strongly attract electrons from other elements during reactions.
• They typically exist as diatomic molecules, like \( \text{Cl}_2 \) or \( \text{F}_2 \), in their elemental form.
• Commonly used in disinfectants and bleach due to their reactivity.

Examples of halogens are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Their reactivity plays a significant role in our day-to-day life, from purifying water to maintaining pool cleanliness.

Transition Metals

Transition metals occupy the d-block of the periodic table, specifically found in Groups 3 to 12. These elements are crucial in many industrial processes and are characterized by their ability to form complex compounds due to the filling of their d orbitals.
Let's look at what makes transition metals unique:

• They exhibit variable oxidation states, which allows them to participate in various chemical reactions.
• Many of these metals are good conductors of electricity and heat.
• They are often used as catalysts in chemical reactions. Platinium and palladium, for example, are critical in catalytic converters for car exhausts.

Some well-known transition metals include iron (Fe), nickel (Ni), and copper (Cu). Understanding their properties is essential for applications in construction, electronics, and even in creating jewelry.