Question

Using the periodic table only, arrange the elements in each set in order of increasing EN: (a) I, Br, \(\mathrm{N}\) (b) \(\mathrm{Ca}, \mathrm{H}, \mathrm{F}\)

Short answer

Set (a): I < Br < N, Set (b): Ca < H < F

Step-by-step solution

Understand Electronegativity (EN)

Electronegativity is a measure of an atom's ability to attract and bind with electrons. The higher the electronegativity, the stronger the attraction. Electronegativity values typically increase across a period and decrease down a group in the periodic table.

Find Electronegativity Values

Use the periodic table to find the electronegativity values for each element in set (a) and set (b). Common values are: - Iodine (I): 2.66- Bromine (Br): 2.96- Nitrogen (N): 3.04- Calcium (Ca): 1.00- Hydrogen (H): 2.20- Fluorine (F): 3.98

Arrange Set (a) Elements by Increasing EN

Compare the electronegativity values for I (2.66), Br (2.96), and N (3.04). Arrange them in order of increasing electronegativity: I < Br < N.

Arrange Set (b) Elements by Increasing EN

Compare the electronegativity values for Ca (1.00), H (2.20), and F (3.98). Arrange them in order of increasing electronegativity: Ca < H < F.

Key concepts

Periodic Table

The periodic table is a systematic arrangement of elements in rows and columns. Each element is placed according to its atomic number, electron configurations, and recurring chemical properties.
The periodic table includes vertical columns called groups and horizontal rows called periods. For example, iodine (I) and bromine (Br) belong to the same group but are in different periods, while nitrogen (N) is in a different group entirely.
Understanding the layout of the table helps predict trends and properties of elements, such as electronegativity. When looking at the periodic table, moving from left to right across a period typically increases electronegativity; moving down a group usually decreases it.

Chemical Properties

Chemical properties refer to how an element behaves in chemical reactions. Electronegativity is one such property and it indicates how strongly an atom can attract and hold onto electrons in a bond.
Elements with high electronegativity, like fluorine (F), hold electrons tightly and are typically more reactive.
Conversely, elements like calcium (Ca) with lower electronegativity are less able to attract electrons and are often more willing to lose them in reactions.
This influences how elements interact with each other and dictates the nature of bonds they can form.

• Ionic bonds often form between elements with a large difference in electronegativity values.
• Covalent bonds are typically formed between elements with similar electronegativity values.

Element Arrangements

Arranging elements according to their electronegativity helps in understanding their reactivity and the types of bonds they are likely to form.
For instance, in the exercise provided, we need to arrange Iodine (I), Bromine (Br), and Nitrogen (N) in set (a) by their increasing electronegativity values.
This requires identifying and comparing their respective electronegativity values:

• Iodine (I): 2.66
• Bromine (Br): 2.96
• Nitrogen (N): 3.04

Thus, the arrangement is: I < Br < N.
The same approach is applied to Calcium (Ca), Hydrogen (H), and Fluorine (F) in set (b):

• Calcium (Ca): 1.00
• Hydrogen (H): 2.20
• Fluorine (F): 3.98

The resulting order is: Ca < H < F.

Trends in Electronegativity

Electronegativity trends are key to predicting how elements behave. Across a period (left to right), electronegativity increases because added protons increase the attraction between the nucleus and electrons.
However, down a group (top to bottom), electronegativity decreases because additional electron shells increase distance and reduce the nucleus' pull on the outer electrons.
For example:

• Carbon (C) has higher electronegativity than Sodium (Na) within the same period.
• Bromine (Br) has lower electronegativity than Fluorine (F) within the same group.

These patterns help chemistry students predict interactions and bond types among various elements.