Question

Which of these elements are nonmetals? a. bromine, \(\mathrm{Br} \quad\) b. carbon, \(\mathrm{C} \quad\) c. boron, \(\mathrm{B}\) d. thallium, \(\mathrm{TI} \quad\) e. phosphorus, \(\mathrm{P} \quad\) f. aluminum, \(\mathrm{Al}\)

Short answer

The nonmetals are bromine (Br), carbon (C), and phosphorus (P).

Step-by-step solution

Understand the Question

The question asks us to identify which elements from a list are classified as nonmetals. We need to compare each element to the general characteristics of nonmetals.

Define Characteristics of Nonmetals

Nonmetals are elements typically characterized by being poor conductors of heat and electricity, having high electronegativities, and often existing in gaseous or brittle solid forms. In the periodic table, nonmetals are located on the right side except for hydrogen, which is on the top-left.

Examine Element a: Bromine, \( \text{Br} \)

Bromine is in group 17 of the periodic table, which is known as the halogens. Halogens are nonmetals. Therefore, bromine is a nonmetal.

Examine Element b: Carbon, \( \text{C} \)

Carbon is in group 14, located just to the right part of the periodic table where nonmetals are typically found. It is known for being a nonmetal due to its chemical properties.

Examine Element c: Boron, \( \text{B} \)

Boron is located in the p-block but is on the border between metals and nonmetals. Technically, it is classified as a metalloid, which means it exhibits properties of both metals and nonmetals, but it is not classified solely as a nonmetal.

Examine Element d: Thallium, \( \text{TI} \)

Thallium is a post-transition metal, located in group 13 of the periodic table. It exhibits characteristics typical of metals.

Examine Element e: Phosphorus, \( \text{P} \)

Phosphorus is in group 15 and is considered a nonmetal, existing in several allotropic forms like white, red, and black phosphorus.

Examine Element f: Aluminum, \( \text{Al} \)

Aluminum is a group 13 element and is categorized as a metal, known for its good conductivity and malleable characteristics.

Key concepts

periodic table

The periodic table is an organized chart of chemical elements, arranged by increasing atomic number, which represents the number of protons in an element's nucleus. This arrangement groups elements with similar properties in the same column, known as a group.

On the periodic table, elements are generally divided into metals, nonmetals, and metalloids.

• Metals are usually found on the left and have characteristics such as being good conductors of electricity and heat.
• Nonmetals, on the other hand, are found on the right side and typically have different properties, including poor conductivity.
• In between these two groups, you can find metalloids, which exhibit properties of both metals and nonmetals.

Understanding the organization of the periodic table is fundamental to predicting the behavior of elements, as well as their interactions with one another.

chemical properties

Chemical properties of elements determine how they will react with other substances. These properties are crucial in identifying and categorizing elements like nonmetals, metals, and metalloids.

For nonmetals, some key chemical properties include:

• High electronegativity, meaning they have a greater tendency to attract electrons when forming chemical bonds.
• High ionization energies, indicating the energy needed to remove an electron from an atom.
• Typically they form acidic oxides and negatively-charged ions in compounds.

Metalloids, which include elements like boron, have chemical properties in between metals and nonmetals. They can act as semiconductors, essential in electronic devices, showing characteristics like:

• Malleability, allowing them to be shaped without breaking.
• The ability to form amphoteric oxides that can react both as acids and bases.

These chemical properties are what determine how elements like carbon and phosphorus, two nonmetals, interact within chemical reactions.

metalloids

Metalloids are elements that straddle the line between metals and nonmetals on the periodic table. They possess a mix of chemical and physical properties from both categories, making them unique and versatile in their use.

Some well-known metalloids include boron (B), silicon (Si), and arsenic (As). These elements:

• Can conduct electricity better than nonmetals but not as well as metals, often making them useful in semiconductor technology.
• Exhibit varied chemical reactivity, acting as either metals or nonmetals in different situations.
• Have structural characteristics, like luster and brittleness, typically associated with their appearance.

Because they have such diverse characteristics, metalloids are essential, particularly in modern technology and industrial applications.

halogens

Halogens are a group of nonmetals located in group 17 of the periodic table. They include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

These elements share several distinct characteristics:

• They are highly reactive, particularly with alkali and alkaline earth metals, to form salts.
• They exist in various states at room temperature: fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids.
• Their reactivity decreases as you move down the group, but they all have high electronegativities, allowing them to attract electrons easily in chemical reactions.

Halogens play significant roles in both biological systems and industrial applications, making them an important study focus in chemistry. Understanding their properties aids in grasping broader concepts of nonmetal behaviors.