Question

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

Short answer

The elements corresponding to the given electron configurations are: Titanium (Ti) with 22 electrons, Phosphorus (P) with 15 electrons, Arsenic (As) with 33 electrons, and Chlorine (Cl) with 17 electrons. Based on the periodic table and electronegativity trends, the order in increasing electronegativity is: Titanium (Ti) -> Arsenic (As) -> Phosphorus (P) -> Chlorine (Cl).

Step-by-step solution

Identify the elements based on their electron configurations

To identify the elements based on their electron configurations, we can use the electron configurations to find the atomic number of each element. The atomic number or proton number refers to the number of protons found in the nucleus of an atom and determines the element: Element 1: [Ar] 4s^1 3d^3 - This configuration has a total of 18 + 1 + 3 = 22 electrons, so the atomic number is 22. The element is Titanium (Ti). Element 2: [Ne] 3s^2 3p^3 - This configuration has a total of 10 + 2 + 3 = 15 electrons, so the atomic number is 15. The element is Phosphorus (P). Element 3: [Ar] 4s^2 3d^10 4p^3 - This configuration has a total of 18 + 2 + 10 + 3 = 33 electrons, so the atomic number is 33. The element is Arsenic (As). Element 4: [Ne] 3s^2 3p^5 - This configuration has a total of 10 + 2 + 5 = 17 electrons, so the atomic number is 17. The element is Chlorine (Cl).

Ranking the elements in order of increasing electronegativity

Now that we have identified the elements, we can use the periodic table to determine the order of increasing electronegativity. In general, electronegativity increases from left to right across a period and decreases from top to bottom down a group. Using this trend, we can rank the electronegativities of these elements: 1. Titanium (Ti) - Located in Group 4 and Period 4: Electronegativity = 1.54 2. Phosphorus (P) - Located in Group 15 and Period 3: Electronegativity = 2.19 3. Arsenic (As) - Located in Group 15 and Period 4: Electronegativity = 2.18 4. Chlorine (Cl) - Located in Group 17 and Period 3: Electronegativity = 3.16 Now, we can rank them in order of increasing electronegativity: Ti < As < P < Cl. So the final order in increasing electronegativity: Titanium (Ti) -> Arsenic (As) -> Phosphorus (P) -> Chlorine (Cl).

Key concepts

Electronegativity

Understanding electronegativity is essential for mastering chemistry concepts. It refers to the tendency of an atom to attract a shared pair of electrons (or electron density) towards itself in a chemical bond. Different elements show varying degrees of electronegativity due to their atomic structure and electron configuration.

Linus Pauling developed a scale, known as the Pauling scale, which is commonly used to measure the electronegativity of elements. On this scale, Fluorine is assigned the highest value of around 4.0, as it is the most electronegative element. Elements with higher electronegativities, like Chlorine in the exercise, tend to pull electrons closer in bonds, which can influence the polarity and reactivity of molecules. Understanding these trends can immensely help with predicting the behavior of elements in chemical reactions.

Periodic Table Trends

The periodic table is not just a collection of elemental symbols, but a map of chemical properties neatly organized into trends. These trends are consequences of the atomic structure and electron configurations of the elements. One of the key trends is electronegativity, which, as mentioned, increases as you move from left to right across a period and decreases as you move down a group.

Why is this the case? As you go from left to right across a period, the number of protons increases, which increases the nuclear charge. This pulls the electrons closer, resulting in higher electronegativity. Moving down a group, the atomic radius increases due to additional electron shells, which makes it harder for the nucleus to attract electrons from far away, thus, decreasing electronegativity.

Other important trends include atomic radius, ionization energy, and electron affinity, all of which are also intimately connected to the concept of electronegativity. By understanding these periodic trends, students can make better-informed predictions about the chemical behavior of elements.

Atomic Number

The atomic number, a fundamental concept in chemistry, defines the identity of an element. As seen in the exercise, each element has a unique number of protons in its nucleus, and this number is referred to as the atomic number. For example, titanium has an atomic number of 22. It's important to note that while elements can have varying numbers of neutrons and electrons, it's the proton count that determines what element it is.

In the periodic table, elements are sorted by increasing atomic number, which dictates their position and ultimately, the trends we observe. The atomic number is also responsible for the structure of the electron cloud around an atom. As the atomic number increases, so does the number of electrons, leading to more complex electron configurations which influence chemistry's predictive models, such as reactivity and bonding patterns.