Problem 39 - Chemistry: The Central Science in SI Units, Global Edition

Question

Using only the periodic table as your guide, select the most electronegative atom in each of the following sets: (a) Se, Te, \(\mathrm{Br}, \mathrm{I} ;(\mathbf{b}) \mathrm{Be}, \mathrm{Mg}, \mathrm{C}, \mathrm{Si} ;(\mathbf{c}) \mathrm{Al}, \mathrm{Si}, \mathrm{P}, \mathrm{S} ;(\mathbf{d}) \mathrm{O}, \mathrm{P}, \mathrm{Ge}, \mathrm{In}\).

Step-by-Step Solution

Answer

The most electronegative elements in each set are: (a) \(Br\) (b) \(C\) (c) \(S\) (d) \(O\)

Step 1: Set (a): Se, Te, Br, I

Referring to the periodic table, we can see that Se, Te, Br, and I are in the same period with increasing atomic number. As electronegativity increases from left to right in a period, the most electronegative element in this set is \(Br\).

Step 2: Set (b): Be, Mg, C, Si

In this set, Be and Mg belong to Group 2 and C and Si belong to Group 14. Since electronegativity increases from left to right in a period, C and Si should be more electronegative than Be and Mg. Now, between C and Si, Si is below C in the periodic table, and electronegativity generally decreases down a group. Therefore, the most electronegative element in this set is \(C\).

Step 3: Set (c): Al, Si, P, S

In this set, Al, Si, P, and S are in the same period with increasing atomic number. Electronegativity increases from left to right in a period. Therefore, the most electronegative element in this set is \(S\).

Step 4: Set (d): O, P, Ge, In

In this set, O and P belong to Group 16 and 15 respectively, while Ge and In belong to Group 14 and 13 respectively. Electronegativity increases from left to right in a period, so O and P should be more electronegative than Ge and In. Between O and P, P is below O in the periodic table, and electronegativity generally decreases down a group. Therefore, the most electronegative element in this set is \(O\). To summarize the most electronegative elements in each set: (a) \(Br\) (b) \(C\) (c) \(S\) (d) \(O\)

Key Concepts

Periodic Table

The periodic table is a powerful tool that organizes all known chemical elements in a structured manner. Each element is placed in a specific position based on its atomic number, which represents the number of protons found in the nucleus of its atoms. The table is arranged in rows and columns, known respectively as periods and groups.

One of the fascinating aspects of the periodic table is how it reveals trends in element properties, such as electronegativity. As you move from left to right across a period, electronegativity generally increases. This means elements on the right side of the same period are more electronegative than those on the left. Furthermore, as you descend down a group, electronegativity typically decreases. This arrangement allows us to predict an element's properties, including how it will react chemically, based on its position in the table.

Atomic Number

The atomic number is a crucial identifier for a chemical element. It equals the number of protons found in an atom's nucleus. This number not only determines what element we are examining, but also influences the element's chemical properties and its place on the periodic table.

The atomic number is located above the element symbol on the periodic table. Each element has a unique atomic number. For example, carbon has an atomic number of 6, meaning each carbon atom has six protons. This distinctive feature is what makes carbon different from all other elements. Understanding the atomic number is essential for comprehending an element's behavior and reactivity, particularly when comparing different elements' electronegativity.

Chemical Elements

Chemical elements are pure substances consisting of only one type of atom, distinguished by their atomic numbers. Each element has a unique set of properties and plays specific roles in chemical reactions.

Elements are the building blocks of matter and are organized in the periodic table in such a way that reveals similarities and trends in their physical and chemical behaviors. For example, groups on the periodic table contain elements with similar chemical properties due to their valence electron configurations. This makes it easier to predict how different elements will react with one another.

Learning about chemical elements helps us not only understand the composition and structure of substances, but also their reactivity. This understanding is vital, especially when examining the nature of elements like carbon or oxygen, which are often compared for their electronegativity.

Electronegativity Trends

Electronegativity is a measure of an atom's ability to attract and hold onto electrons, especially when forming a chemical bond. This property varies across the periodic table, following clear trends.

One key trend is that electronegativity tends to increase as you move from left to right across a period. This happens because the number of protons in the nucleus increases, boosting the positive charge, which attracts electrons more strongly. Conversely, electronegativity often decreases as you move down a group, since the added electron shells push the valence electrons further from the nucleus, diminishing the nuclear pull on bonding electrons.

These trends are valuable in predicting and comparing the chemical behavior of different elements. An understanding of these patterns allows chemists to anticipate which elements will likely dominate in attracting electrons during reactions, as seen in the exercise where elements like bromine or oxygen are identified as the most electronegative in their respective sets.