Question

Problem \(1.3\) Judging from their relative positions in the Periodic Table, which element in each set is the more electronegative? (a) Lithium or potassium (b) Nitrogen or phosphorus (c) Carbon or silicon

Short answer

Answer: The more electronegative elements in each pair are lithium (Li), nitrogen (N), and carbon (C).

Step-by-step solution

Determining electronegativity of lithium and potassium

We first need to locate lithium (Li) and potassium (K) in the Periodic Table. Li is in Group 1 and Period 2, while K is in Group 1 and Period 4. As we move down a group, electronegativity decreases, so the more electronegative element is lithium (Li).

Determining electronegativity of nitrogen and phosphorus

We now locate nitrogen (N) and phosphorus (P) in the Periodic Table. N is found in Group 15 and Period 2, while P is in Group 15 and Period 3. Electronegativity decreases down a group, so nitrogen (N), being in a higher period, is more electronegative than phosphorus (P).

Determining electronegativity of carbon and silicon

Finally, we locate carbon (C) and silicon (Si) in the Periodic Table. Carbon (C) is in Group 14 and Period 2, while silicon (Si) is in Group 14 and Period 3. Since electronegativity decreases down a group, carbon (C), being higher up in the Periodic Table, is more electronegative than silicon (Si).

Key concepts

Periodic Table

The periodic table is an arrangement of all known chemical elements organized by their atomic number, electron configuration, and recurring chemical properties. Elements are presented in a tabular format, where each element has its own specific place in the grid. This layout helps scientists understand elements' properties, including trends such as electronegativity, ionization energy, and atomic size.

Electronegativity is a measure of an atom's ability to attract and hold onto electrons when bonded with another atom. In the periodic table, this property shows a pattern. As you move from left to right across a period, electronegativity tends to increase. This is because elements have more protons in the nucleus and want to 'grab' electrons to complete their outer shell. Conversely, as you move down a group, electronegativity tends to decrease as atoms have additional electron shells, which reduces the nucleus's pull on the outermost electrons. The periodic table's organization helps predict which elements are more electronegative by their positions.

Element Groups

Element groups, also known as families, are columns in the periodic table. Each group contains elements that have similar chemical and physical properties. This similarity arises because elements in a group have the same number of electrons in their outer shell, which influences how they react with other substances.

For example, in the exercise step-by-step solutions, both lithium (Li) and potassium (K) belong to Group 1, known as the alkali metals. As we move down this group from lithium to potassium, the atoms get larger due to additional electron shells. This increase in atomic size affects various properties, including electronegativity, which decreases as more electron shells are added. However, elements within the same group often react similarly, so by understanding one member, you can predict the behavior of others in the group.

Chemical Periods

Chemical periods are the horizontal rows on the periodic table. Elements in the same period have differing properties, but they all have the same number of atomic orbitals. For instance, elements in Period 2, such as lithium (Li), nitrogen (N), and carbon (C), all have two electron shells.

Periods help illustrate how element properties change across a row. Across a period from left to right, atoms gain more protons and electrons. This trend increases the electronegativity as the nucleus becomes more positive and attracts electrons more strongly. In the step-by-step solution, elements like nitrogen in Period 2 are contrasted with phosphorus in Period 3. Across similar groups, the higher period number usually means more electron shells, which can result in lower electronegativity. Therefore, periods not only demonstrate how elements differ but also how they transition and adapt to form bonds with other elements.