Problem 40 - Chemistry The Central Science In Si Units

Question

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

Step-by-Step Solution

Answer

(a) Boron, (b) Arsenic, (c) Aluminium, (d) Sodium.

Step 1: Identify Group 13 Elements

Group 13 of the periodic table consists of Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), and Thallium (Tl). These elements are found in the 13th column of the periodic table.

Step 2: Determine Most Electronegative in Group 13

In Group 13, Boron is the most electronegative element. Electronegativity generally decreases down a group, and Boron is at the top of Group 13.

Step 3: Identify Elements As, Se, Br

The elements given are Arsenic (As), Selenium (Se), and Bromine (Br), which are located in groups 15, 16, and 17, respectively.

Step 4: Determine Least Electronegative in As, Se, Br

Electronegativity increases across a period from left to right. Among As, Se, and Br, Arsenic has the lowest electronegativity as it is farthest to the left.

Step 5: Identify Elements K, Mg, Al, In

Potassium (K), Magnesium (Mg), Aluminium (Al), and Indium (In) are located in groups 1, 2, 13, and beyond, respectively.

Step 6: Determine Most Electronegative in K, Mg, Al, In

Electronegativity increases from left to right across a period. Among K, Mg, Al, In, Aluminium (Al) is the most electronegative since it is farthest to the right.

Step 7: Identify Elements Na, Be, Si, Ar

The elements are Sodium (Na), Beryllium (Be), Silicon (Si), and Argon (Ar), located in groups 1, 2, 14, and 18, respectively.

Step 8: Determine Most Ionic with Br

Ionic compounds typically form between metals and nonmetals. Of the elements given, Sodium (Na), a metal, is most likely to form an ionic compound with Bromine (Br), a nonmetal.

Key Concepts

Electronegativity

Electronegativity is a chemical property that describes the tendency of an atom to attract electrons towards itself in a chemical bond. This concept is vital to understand chemical bonding and molecular structure.
It is measured on the Pauling scale, named after chemist Linus Pauling.

• Elements with higher electronegativity will have a stronger pull on electrons.
• Fluorine is the most electronegative element, located at the far right of the periodic table.

In the context of the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group. This is because of the increase in the number of protons across a period, making the nucleus attract bonding electrons more strongly, and the increase in the number of energy levels down a group, which places the outer electrons further from the nucleus and reduces this attraction.

Ionic Compounds

Ionic compounds are formed when atoms transfer electrons from one to another, resulting in a metal and a non-metal pairing together.
This happens primarily due to the attraction between positively charged ions (cations) and negatively charged ions (anions).

• Typically, metals, which lose electrons, become cations.
• Non-metals, which gain electrons, become anions.

The driving force for forming ionic compounds is the achievement of a stable electron configuration, often resembling the nearest noble gas. For instance, Sodium (Na) easily forms an ionic bond with Bromine (Br) because sodium donates an electron to achieve the configuration of Neon, while bromine accepts an electron to achieve the configuration of Krypton. This electron exchange results in oppositely charged ions that form a stable ionic bond.

Group Elements

Group elements refer to elements that belong to the same vertical column, or group, in the periodic table.
These elements share similar chemical properties and valence electron configurations due to their common group identity.

• For example, Group 13 includes Boron (B), Aluminium (Al), and Gallium (Ga), among others.
• The properties of group elements, such as reactivity and electronegativity, change predictably within the group.

In an exercise focusing on electronegativity, it's essential to note that elements higher up in a group are generally more electronegative. This is illustrated in Group 13 by Boron being more electronegative than Indium down the group. Knowledge of these group trends helps in predicting properties of elements, which is useful in solving chemistry problems.