Question

Identify the following elements based on their electron configurations and rank them in order of increasing electronegativity: \([\mathrm{Ar}] 4 s^{1} 3 d^{5} ;[\mathrm{Ne}] 3 s^{2} 3 p^{3} ;[\mathrm{Ar}] 4 s^{2} 3 d^{10} 4 p^{3} ;[\mathrm{Ne}] 3 s^{2} 3 p^{5}\).

Short answer

The elements are identified as Chromium (Cr), Phosphorus (P), Arsenic (As), and Chlorine (Cl). They can be ranked in order of increasing electronegativity as follows: Chromium (Cr) < Arsenic (As) < Phosphorus (P) < Chlorine (Cl).

Step-by-step solution

Identify the elements by their electron configurations

Transformer notation can be used to find the electron configurations of the given elements: 1. \([\mathrm{Ar}] 4s^1 3d^5\) 2. \([\mathrm{Ne}] 3s^2 3p^3\) 3. \([\mathrm{Ar}] 4s^2 3d^{10} 4p^3\) 4. \([\mathrm{Ne}] 3s^2 3p^5\) Now let's identify the elements. 1. The element that has configuration \([\mathrm{Ar}]4s^1 3d^5\) is the 6th element in the 4th period (as Argon is the last element in the 3rd period). The 6th element in the 4th period is Chromium (Cr). 2. The element with configuration \([\mathrm{Ne}] 3s^2 3p^3\) is the 5th element in the 3rd period (as Neon is the last element in the 2nd period). The 5th element in the 3rd period is Phosphorus (P). 3. The element with configuration \([\mathrm{Ar}] 4s^2 3d^{10} 4p^3\) is the 5th element in the 4th period after Argon. The 5th element in the 4th period after Argon is Arsenic (As). 4. The element with configuration \([\mathrm{Ne}] 3s^2 3p^5\) is the 2nd last element in the 3rd period (as Neon is the last element in the 2nd period). The 2nd last element in the 3rd period is Chlorine (Cl). So, the elements are Chromium (Cr), Phosphorus (P), Arsenic (As), and Chlorine (Cl).

Rank the elements by electronegativity

Now that we have identified the elements, we need to rank them in order of increasing electronegativity. Using the periodic table, we can determine the electronegativity values of these elements: - Chromium (Cr): 1.66 - Phosphorus (P): 2.19 - Arsenic (As): 2.18 - Chlorine (Cl): 3.16 The electronegativity values tell us that these elements can be ranked in the following order (from the least electronegative to the most electronegative): Chromium (Cr) < Arsenic (As) < Phosphorus (P) < Chlorine (Cl) In conclusion, the given elements, identified by their electron configurations, can be ranked in order of increasing electronegativity as follows: Chromium (Cr), Arsenic (As), Phosphorus (P), and Chlorine (Cl).

Key concepts

Electronegativity

Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond. It's like the atom's pull or grip on electrons when it forms a molecule. This property is crucial for understanding how elements interact with each other, especially in covalent bonds.

Several factors determine an element's electronegativity:

• Nuclear charge: The more protons an atom has, the stronger its positive charge, allowing it to attract electrons more effectively.
• Atomic size: Smaller atoms with electrons closer to the nucleus tend to have higher electronegativity because the electrons feel the nucleus's pull more strongly.
• Electron shielding: Inner electron layers can shield outer electrons from the nucleus, reducing electronegativity.

On the periodic table, electronegativity increases across a period from left to right and decreases down a group. For example, in our exercise, Chlorine (Cl) is the most electronegative among Chromium (Cr), Phosphorus (P), and Arsenic (As) due to its position in the periodic table as it is further to the right and higher in its group.

Element Identification

Identifying elements by their electron configuration involves understanding how electrons fill the atomic orbitals. The electron configuration of an element tells us the distribution of electrons in the shells and subshells within an atom. This pattern helps identify an element's position in the periodic table.

To read electron configurations:

• Understand the principle quantum number (n) which indicates the main energy level or shell of an electron.
• Look for subshell letters (s, p, d, f) showing the shape of the orbitals.
• Check the superscript numbers indicating the number of electrons in those orbitals.

For example, the configuration \( \mathrm{[Ar]} 4s^1 3d^5 \) refers to Chromium (Cr) because it follows Argon (Ar), and the additional electrons populate the 4s and 3d subshells up to Chromium. By examining these configurations, we identified Chromium, Phosphorus, Arsenic, and Chlorine in the original problem.

Periodic Table Trends

The periodic table is organized in such a way that it reveals several trends among elements. These trends help predict and understand the chemical properties of elements.

Key periodic table trends include:

• Electronegativity: Increases across a period and decreases down a group, as seen with Chlorine being more electronegative than Phosphorus or Chromium.
• Atomic radius: This is the size of an atom, which decreases across a period due to increased nuclear charge attracting electrons closer and increases down a group as more electron shells are added.
• Ionization energy: The energy required to remove an electron from an atom. This usually increases across a period and decreases down a group.

Recognizing these trends is essential for understanding how elements behave and interact. For instance, elements in the same group often have similar chemical properties due to having the same number of electrons in their outer shell. This predictable nature of the periodic table aids in tasks like ranking elements by electronegativity, as we did in the exercise for Chromium, Phosphorus, Arsenic, and Chlorine.