Question

By referring only to the periodic table, select (a) the most electronegative element in group \(13 ;(\mathbf{b})\) the least electronegative element in the group As, Se and Br; (c) the most electronegative element in the group \(\mathrm{K}, \mathrm{Mg}, \mathrm{Al}\) and \(\mathrm{In} ;(\mathbf{d})\) the element in the group \(\mathrm{Na}, \mathrm{Be}, \mathrm{Si}\), Ar, that is most likely to form an ionic compound with \(\mathrm{Br}\).

Short answer

The short answer is: (a) the most electronegative element in group 13 is B (Boron); (b) the least electronegative element in the group As, Se, and Br is As (Arsenic); (c) the most electronegative element in the group K, Mg, Al, and In is Al (Aluminum); (d) the element in the group Na, Be, Si, Ar that is most likely to form an ionic compound with Br is Na (Sodium).

Step-by-step solution

Identifying the most electronegative element in group 13.

To find the most electronegative element in group 13, we need to look at the members of group 13 which are B, Al, Ga, In, and Tl. Since electronegativity decreases as we go down in a group, the most electronegative element in group 13 is B (Boron).

Identifying the least electronegative element in the group As, Se, and Br.

To find the least electronegative element in this group, we need to compare the electronegativities of As, Se, and Br. As and Se are in the same period, while Br is in the next period below them. Because electronegativity decreases as we move down in a group, Br will be more electronegative than As and Se. Comparing As and Se, As is to the left of Se, and since electronegativity increases as we move from left to right in a period, As will be less electronegative than Se. Thus, the least electronegative element is As (Arsenic).

Identifying the most electronegative element in the group K, Mg, Al, and In.

To find the most electronegative element in this group, we need to look at their positions on the periodic table: - K is in group 1 and period 4. - Mg is in group 2 and period 3. - Al is in group 13 and period 3. - In is in group 13 and period 5. Since electronegativity increases from left to right across a period and decreases from top to bottom within a group, Al is the most electronegative element in the given group.

Identifying the element in the group Na, Be, Si, Ar that is most likely to form an ionic compound with Br.

To find the element that is most likely to form an ionic compound with Br, we need to identify the element with the highest difference in electronegativity since ionic compounds are formed between elements with large electronegativity differences. The elements given are: - Na is in group 1 and period 3. - Be is in group 2 and period 2. - Si is in group 14 and period 3. - Ar is in group 18 and period 3. Since Br is in group 17 and period 4, the electronegativity difference between Na and Br is the highest among the given elements. Therefore, Na (Sodium) is most likely to form an ionic compound with Br.

Key concepts

Periodic Table

The periodic table is a powerful tool to understand the properties of elements, including electronegativity. Electronegativity is the tendency of an atom to attract electrons towards itself. This property can be predicted accurately by looking at the periodic table.
As you move from left to right across a period (row), electronegativity typically increases because atoms have more protons, which results in a stronger positive charge attracting electrons.
Conversely, as you move down a group (column), electronegativity decreases. This occurs because the addition of electron shells makes the outer electrons further from the nucleus, resulting in a weaker attraction. These trends help you determine the relative electronegativity of elements quickly using the periodic table.

Ionic Compounds

Ionic compounds form when atoms with significant differences in electronegativity transfer electrons between them. This electron transfer results in the formation of ions; positively charged cations and negatively charged anions.
The classic example is the formation of sodium chloride (NaCl). Sodium (Na) has a low electronegativity and is likely to lose an electron, whereas chlorine (Cl) has a high electronegativity and is likely to gain an electron.
This difference in electronegativity creates a strong electrostatic attraction between Na and Cl, resulting in the formation of an ionic bond. In general, elements on the far left of the periodic table (metals) tend to form ionic bonds with elements on the far right (non-metals), excluding the noble gases.

Group Trends

The periodic table is organized in a way that helps us understand element trends, such as electronegativity, within the same group.
Groups are vertical columns in the periodic table that categorize elements by shared characteristics. As mentioned, electronegativity decreases down a group. This is due to increasing atomic size and electron shielding, which reduce the nucleus' pull on valence electrons.
For instance, in group 13, boron is the most electronegative element, as it is at the top of the group, while thallium, found at the bottom, is the least. Understanding these trends can help you quickly deduce various chemical properties and interactions of elements.

Element Selection

When choosing elements based on electronegativity or the potential to form specific types of bonds, you must consider their positions in the periodic table. For instance, if looking to form an ionic compound, recognize that such a compound will form between elements with a substantial electronegativity difference.
In the exercise provided, sodium (Na), a highly reactive metal, and bromine (Br), a highly electronegative non-metal, combine to form an ionic bond.
In selections for tasks like these, look for elements from opposite ends of the periodic table groups or periods that complement each other in terms of electron donation and acceptance, fulfilling stable electronic configurations.