Question

For each of the following elements, write its chemical symbol, determine the name of the group to which it belongs (Table $2.3),$ and indicate whether it is a metal, metalloid, or nonmetal: (a) potassium, (b) iodine, (c) magnesium, (d) argon, (e) sulfur.

Short answer

(a) Potassium: Chemical symbol - $K$, Group - Alkali metals (Group 1), Type - Metal. (b) Iodine: Chemical symbol - $I$, Group - Halogens (Group 17), Type - Nonmetal. (c) Magnesium: Chemical symbol - $Mg$, Group - Alkaline earth metals (Group 2), Type - Metal. (d) Argon: Chemical symbol - $Ar$, Group - Noble gases (Group 18), Type - Nonmetal. (e) Sulfur: Chemical symbol - $S$, Group - Chalcogens (Group 16), Type - Nonmetal.

Step-by-step solution

(a) Potassium

Potassium is an alkali metal, located in group 1 of the periodic table. Its chemical symbol is $K$. Alkali metals are metals. So, potassium is a metal.

(b) Iodine

Iodine is a halogen, present in group 17 of the periodic table. Its chemical symbol is $I$. Halogens are nonmetals. Therefore, iodine is a nonmetal.

(c) Magnesium

Magnesium is an alkaline earth metal, which can be found in group 2 of the periodic table. Its chemical symbol is $Mg$. Alkaline earth metals are metals. Thus, magnesium is a metal.

(d) Argon

Argon is a noble gas, a part of group 18 in the periodic table. Its chemical symbol is $Ar$. Noble gases are nonmetals, so argon is a nonmetal.

(e) Sulfur

Sulfur belongs to the group 16, known as chalcogens, in the periodic table. Its chemical symbol is $S$. Chalcogens include nonmetals and metalloids. Sulfur, specifically, is a nonmetal.

Key concepts

Chemical Symbols

Chemical symbols are the shorthand way of representing chemical elements. Each element on the periodic table is assigned a one- or two-letter symbol, which is derived from its English name or sometimes from its Latin name. For example, potassium is symbolized by $K$ because its Latin name is 'Kalium'. These symbols provide a universal means of identification for elements across different languages and regions.

• Symbols are standardized and recognized worldwide, ensuring clear communication among scientists.
• They are concise, making it easy to write chemical equations and formulas quickly.
• Each chemical symbol starts with a capital letter, and if a second letter is present, it is lowercase; this helps in distinguishing one element from another, such as $C$ for carbon and $Ca$ for calcium.

Element Groups

The periodic table organizes elements into different groups or families, which are columns of elements that share similar chemical properties. Understanding these groups helps predict element behavior in chemical reactions. Each group is identified by a number at the top of the periodic table.

• **Group 1 (Alkali Metals):** These elements, including potassium ($K$), are highly reactive metals.
• **Group 2 (Alkaline Earth Metals):** Contains elements like magnesium ($Mg$). These metals are reactive but less so than alkali metals.
• **Group 17 (Halogens):** This group includes nonmetals like iodine ($I$), which are very reactive.
• **Group 18 (Noble Gases):** Elements such as argon ($Ar$) reside here and are known for their lack of reactivity.
• **Group 16 (Chalcogens):** Includes nonmetals like sulfur ($S$); members of this group can have varied properties.

Understanding element groups enriches the study of chemistry and aids in anticipating element interactions. These groupings highlight trends in electronegativity, atomic size, and ionization energy.

Metals and Nonmetals

The periodic table is not only split horizontally into periods but also vertically into groups that classify elements as metals, nonmetals, or metalloids based on well-defined properties.

• **Metals:** Predominantly located on the left side of the periodic table, metals are known for their conductivity, malleability, and luster. Potassium ($K$) and magnesium ($Mg$) are metals as they exhibit these characteristics.
• **Nonmetals:** Nonmetals, like iodine ($I$), sulfur ($S$), and argon ($Ar$), are found on the right side of the periodic table. They typically have higher electronegativities and are poor conductors of heat and electricity.
• **Metalloids:** These elements, which are not heavily mentioned in this exercise, possess properties that are intermediate between metals and nonmetals.

This classification scheme helps us anticipate an element's behavior and its potential applications in technology and industry.