Introduction

Relevance of the Topic

The periodic table is the heart of Chemistry, a reference tool that gathers and organizes all the known elements in our Universe. Within the periodic table, Nonmetals are essential elements to understand the chemistry of substances, as they are the ones that usually form covalent bonds, one of the main ways elements can bond.

Through the study of Nonmetals and their behaviors, we can unveil the incredible diversity and complexity of the substances that surround us. These elements form the basis of Organic Chemistry, one of the most extensive and important branches of Chemistry.

Contextualization

Nonmetals are located to the right on the periodic table, after the metalloids. In terms of properties and behavior, they characterize the change from metallic to non-metallic properties along the horizontal line of the table.

In the Chemistry curriculum of the 1st year of High School, the study of Nonmetals comes after the introduction to atomic structure and the periodic table, and serves as a bridge to the study of Chemical Bonds.

At this point, we should have already discussed the most familiar elements of everyday life (hydrogen, carbon, oxygen, nitrogen, phosphorus, and sulfur) and now we will expand our knowledge, delving into the aspects of other Nonmetals and how they contribute to the formation of substances in our world.

Theoretical Development

Components

• Periodic Table: The study of Nonmetals is based on the structure and organization of the Periodic Table. Remembering the organization of elements by atomic number and their electronic distributions is crucial for identifying Nonmetals and understanding their characteristics.

• Nonmetallicity: The fundamental characteristic of nonmetals is their tendency to gain electrons and form negative ions. It is this property that defines the non-metallic nature of nonmetals, although some of them (like Hydrogen) may exhibit metallic properties under certain conditions.

• Atomic Radius: The atomic radius of nonmetals tends to decrease along a period of the periodic table. This is due to the addition of protons to the atomic nucleus, which increases the nucleus' attraction for electrons.

• Electronegativity: Nonmetals have high electronegativity, which means they have a great tendency to attract bonding electrons in a compound.

Key Terms

• Nonmetals: Elements that tend to gain electrons, forming negative ions, and have high electronegativity. In their pure state, in the form of molecules, they are insulators or poor conductors of electricity and heat.

• Most Common Nonmetals: Nitrogen, oxygen, fluorine, chlorine, bromine, iodine, and astatine.

• Covalent Bonds: Type of chemical bond that occurs between nonmetal atoms when they share pairs of electrons.

Examples and Cases

• Hydrogen in the Periodic Table: Hydrogen is often placed outside the periodic table. This is because, despite being a nonmetal, it has an unusual electronic configuration (only 1 electron in the valence shell), making it a special case.

• H2O - Water: Water is a classic example of a substance formed by covalent bonds between nonmetals. In this case, hydrogen atoms share their electrons with the oxygen atom, forming a stable molecule.

• Cl2 - Molecular Chlorine: Molecular chlorine is another example of a substance formed by covalent bonds between nonmetals. Each chlorine atom contributes one electron to the shared pair of electrons.

Detailed Summary

Key Points

• Position on the Periodic Table: Nonmetals are located to the right on the periodic table, after the metalloids. They demonstrate the evolution from metallic to non-metallic properties along the horizontal line of the table.

• Nonmetallicity: The fundamental property of nonmetals is their ability to attract electrons, tending to form negative ions. This characterizes them as nonmetals, although some nonmetals, like hydrogen, may exhibit metallic properties under certain conditions.

• Atomic Radius and Electronegativity: The atomic radius of nonmetals tends to decrease along a period, due to the increased attraction force between the atomic nucleus and the valence electrons. They also have high electronegativity, resulting in a strong affinity for electrons.

• Common Nonmetals: Nitrogen, oxygen, fluorine, chlorine, bromine, iodine, and astatine are some of the most commonly found nonmetals.

• Covalent Bonds: Nonmetals are often involved in covalent bonds, which form when two nonmetals share one or more pairs of electrons from their valence shells.

Conclusions

• Understanding nonmetals is crucial to deepen the study of Organic Chemistry and Chemical Bonds, as these elements are fundamental in the formation of compounds through covalent bonds.

• Nonmetals have particular physical and chemical characteristics that make them essential for creating a wide variety of substances and compounds, from the air we breathe to the materials we use in our daily lives.

• Through the exploration of nonmetals, we unravel the complexity and richness of Chemistry, and develop a deeper understanding of the world around us.

Suggested Exercises

1. Locating Nonmetals: Identify the position of nonmetals on the periodic table. What are the most common nonmetals?

2. Properties of Nonmetals: Explain what nonmetallicity is, how the atomic radius of nonmetals behaves on the periodic table, and why they have high electronegativity.

3. Covalent Bonds: Describe what a covalent bond is and give two examples of substances formed by covalent bonds of nonmetals.