Write the name of each element and classify it as a metal, nonmetal, or metalloid. $$ \text {a.}\mathrm{K} \quad \text { b.} \mathrm{Ba} \quad \text { c.I } \quad \text { d.} \mathrm{O} \quad \text {e.} \mathrm{Sb} $$

The distinction between metals and nonmetals is a fundamental concept in chemistry. Metals are known for their shininess, malleability, ductility, and good conductivity for heat and electricity. They tend to lose electrons during chemical reactions, usually forming positive ions. Examples of metals are potassium (K) and barium (Ba), as mentioned in the textbook exercise.

Nonmetals, on the other hand, have a more diverse set of properties and are not as clearly defined as metals. They are poor conductors of heat and electricity, usually brittle when solid, and tend to gain electrons during chemical reactions, forming negative ions. Nonmetals can be gases, like oxygen (O), or solids, like iodine (I). By understanding these properties, students can better predict the behavior of elements during chemical reactions.

The periodic table organizes chemical elements into groups based on their electronic structure, which dictates their chemical behavior. Each group is a vertical column in the periodic table and elements within the same group typically share similar properties. For instance, group 1, the alkali metals, includes potassium (K) and elements in group 2, the alkaline earth metals, include barium (Ba).

Groups are crucial for predicting how elements will interact with each other. Group 17 contains the halogens, like iodine (I), which are highly reactive nonmetals. Group 15, where you'll find antimony (Sb), borders between metals and nonmetals, producing a category known as metalloids. Recognizing an element's group can help students understand its reactivity and the types of chemical compounds it might form.

Chemical elements are the building blocks of all matter. Each element has a unique set of properties and a symbol that scientists use worldwide. For example, Potassium (K), Barium (Ba), Iodine (I), Oxygen (O), and Antimony (Sb) are all chemical elements. Let's briefly explain each one:

• Potassium (K): A metal that reacts vigorously with water and is essential for biological functions.
• Barium (Ba): A metal used in medical imaging and known for its high chemical reactivity.
• Iodine (I): A nonmetal that is a critical component of thyroid hormones.
• Oxygen (O): A nonmetal that is vital for respiration and the most abundant element in the Earth's crust.
• Antimony (Sb): A metalloid that is used in flame retardants and electronics.

Elemental classification is significant in predicting how elements will combine to form chemical compounds and their reactions under different conditions.