Question

Why is oxygen considered a nonmetal?

Short answer

Oxygen is considered a nonmetal due to its location on the periodic table, physical properties, and chemical behavior.

Step-by-step solution

Understanding Element Categories

Elements are classified as metals, nonmetals, or metalloids. Metals are typically lustrous, malleable, and conduct electricity well, whereas nonmetals are poor conductors, often brittle, and not lustrous. Metalloids have properties between those of metals and nonmetals.

Examining Oxygen's Position on the Periodic Table

Oxygen is located on the right side of the periodic table in Group 16. The elements in this region are known for being nonmetals, characterized by their lack of metallic attributes.

Analyzing Oxygen's Physical Characteristics

Oxygen is a colorless, odorless, and tasteless gas at room temperature. It does not exhibit metallic luster and is not a good conductor of electricity or heat, which are typical properties of nonmetals.

Understanding Oxygen's Chemical Behavior

Oxygen tends to gain electrons to form negative ions (specifically, oxide ions: O²⁻) rather than lose electrons to form positive ions, a typical property of nonmetals. This behavior in chemical reactions is indicative of nonmetal elements.

Key concepts

Periodic Table

The periodic table is a powerful tool that organizes all known elements by their atomic number, electron configurations, and recurring chemical properties. It's arranged in rows called periods and columns known as groups.
Elements are placed in specific locations due to the similarities in their properties and behaviors.

• **Groups**: Columns of the periodic table, such as Group 18 which contains the noble gases. Each column has elements with similar chemical behaviors.


• **Periods**: Rows that represent elements with the same number of electron shells. As you move from left to right, each element has an additional proton and electron.

On the far right of the periodic table, you'll find the nonmetals, which include elements like oxygen, nitrogen, and fluorine. These elements lack the qualities typically associated with metals, including malleability and electrical conductivity, hence their classification apart from metals.
Understanding the periodic table helps us predict and explain the behavior of elements in chemical reactions, as seen with oxygen's tendency to form negative ions.

Element Classification

Elements on the periodic table are broadly categorized into metals, nonmetals, and metalloids based on their physical and chemical properties.
This classification helps scientists and students understand and predict an element's behavior in different conditions.
Here's how elements are generally classified:

• **Metals**: These are typically shiny, malleable, ductile, and good conductors of heat and electricity. Common examples include iron and copper.


• **Nonmetals**: Found on the right side of the periodic table, nonmetals generally lack metallic luster, and are poor conductors of heat and electricity. They tend to gain electrons in chemical reactions. Oxygen is a perfect example of a nonmetal.


• **Metalloids**: These elements show a mix of metal and nonmetal characteristics, making them unique. Silicon is a well-known metalloid used in electronics.

The classification highlights the diversity of properties across different elements and helps in understanding why oxygen, with its specific characteristics, is classified as a nonmetal.

Chemical Properties of Oxygen

Oxygen is a vital element with unique chemical properties that distinguish it as a nonmetal. At room temperature, it exists as a diatomic molecule ( O_2 ) and is essential for life on Earth.
Here are some key chemical properties of oxygen:

• **Reactivity**: Oxygen is highly reactive and readily forms oxides with most elements. This reaction involves oxygen gaining electrons, a behavior typical of nonmetals.


• **Electron Configuration**: Oxygen has six electrons in its outer shell, which leads it to gain two additional electrons to achieve a stable octet configuration, forming oxide ions ( O^{2-} ).


• **Combustion**: It supports combustion and is essential in processes like respiration and burning—the chemical reaction involving oxygen and a fuel to release energy.

These properties are fundamental in its role as a nonmetal and help explain why oxygen is essential for processes such as respiration and energy production in living organisms.