Question

Use its place on the periodic table to determine if indium, In, atomic number 49 , is a metal or a nonmetal.

Short answer

Indium is a metal.

Step-by-step solution

Locate Indium on the Periodic Table

Find the position of indium (In) on the periodic table. Indium is located in group 13 and period 5.

Identify the General Area

Recognize the general areas of metals and nonmetals on the periodic table. Most metals are on the left and center (transition metals), while nonmetals are on the right side and towards the top.

Determine the Category Based on Group

Group 13, where indium is located, contains elements classified as post-transition metals or metalloids, rather than nonmetals. This group starts with boron (a metalloid) and typically includes metals from aluminum downwards.

Analyze Indium's Specific Characteristics

Indium shares properties more akin to metals, such as good conductivity and malleability, conforming to the properties of group 13 elements like aluminum and gallium.

Key concepts

Periodic Table Groups

The periodic table is organized into groups and periods, which help in predicting the properties of elements based on their position. Groups are the vertical columns in the periodic table, and there are 18 groups in total. Each group contains elements that share similar chemical properties due to having the same number of valence electrons. This means, elements in the same group will often participate in similar chemical reactions. For example, indium belongs to group 13, which has characteristics shared among its elements such as having three valence electrons. These elements usually form compounds in similar ways due to this shared electron configuration. Periods, on the other hand, are the horizontal rows, indicating the number of electron shells in the atoms of elements in that period. Indium, being in period 5, has five electron shells, which affects its overall size and reactivity. Understanding the position of an element in terms of groups and periods is crucial in predicting its behavior in chemical reactions.

Metal vs Nonmetal

The distinction between metals and nonmetals is a fundamental concept in chemistry and is primarily based on their physical and chemical properties. Metals, such as indium, typically have high electrical and thermal conductivity, good malleability, and a shiny appearance known as luster. They tend to lose electrons rather than gain them in chemical reactions, forming positively charged ions. Nonmetals, in contrast, are poor conductors of electricity and heat, and they are often brittle when solid. They usually have higher electronegativities, meaning they are more likely to gain electrons and form negatively charged ions in chemical reactions. Nonmetals make up most of the p-block of the periodic table, situated to the right-hand side. Therefore, understanding these differences helps in categorizing elements and anticipating their chemical behavior and uses in various applications.

Post-Transition Metals

Post-transition metals, located between the transition metals and metalloids in the periodic table, possess characteristics that are intermediate between these two categories. They show metallic features like malleability and conductivity but to a lesser extent than the transition metals. Often, post-transition metals have a higher resistance to corrosion and less dense atomic structure than their transition metal counterparts. Indium is classified as a post-transition metal. Elements in this category, including indium, often find specialized applications due to their unique properties such as low melting points and softness. For instance, indium is used in the creation of semiconductors and for soldering materials that require a low melting point. Recognizing the classification of indium as a post-transition metal helps in understanding its practical uses and chemical tendencies as it bridges the characteristics between the more robust transition metals and non-metallic elements.