Question

What are chemicals? Give some examples.

Short answer

Chemicals are substances with distinct molecular compositions such as water (H2O), carbon dioxide (CO2), and sodium chloride (NaCl).

Step-by-step solution

Define Chemicals

Chemicals are substances with a distinct molecular composition that are produced by or used in a chemical process. They may either be elements or compounds and are characterized by a set of properties like melting point, boiling point, density, and reactivity.

Give Examples

Some common examples of chemicals include water (H2O), carbon dioxide (CO2), sodium chloride (table salt, NaCl), sulfuric acid (H2SO4), glucose (C6H12O6), and oxygen (O2). These examples span a range from simple molecules like oxygen to more complex ones like glucose.

Key concepts

Chemical Properties

When we talk about chemical properties, we are referring to the inherent characteristics of a substance that become evident during a chemical reaction. These properties dictate how a substance reacts under certain conditions and with other substances, which is crucial for understanding how chemicals will behave in different scenarios.

For instance, the flammability of a substance is a chemical property that describes its ability to burn in the presence of oxygen. Another example is the acidity or basicity (pH) of a solution, which can influence the chemical reactions it participates in. Reactivity with water is another property, where some compounds, like sodium, react violently, whereas others, like vegetable oil, do not react at all.

Understanding chemical properties is essential for predicting the outcomes of chemical reactions. It is also fundamental for fields like pharmacology, where the properties dictate how drugs will interact with the body, or materials science, where the durability and reactivity of materials are of prime importance.

Molecular Composition

The term molecular composition refers to the individual atoms and their quantities that make up a molecule, representing the molecular formula of a substance. It reveals the proportion of each element contained within the chemical and is key to understanding its nature and how it will interact with other chemicals.

For a water molecule, with the chemical formula \( H_2O \), it is comprised of two hydrogen atoms bonded to one oxygen atom. This molecular composition is what gives water its unique properties, such as its ability to dissolve many other substances, its surface tension, and even its role as the 'universal solvent' in biological processes.

In a more complex example, glucose has the molecular composition \( C_6H_{12}O_6 \), which denotes six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. These atoms are arranged in a specific way that gives glucose its role as a primary energy source in organisms. The molecular composition is a blueprint that dictates the potential chemical reactions a substance can undergo, and can be used to predict a substance's physical and chemical properties.

Chemical Examples

Discussing chemical examples helps to solidify our understanding of chemicals in a practical sense. To illustrate, water, or \( H_2O \), is a chemical that's essential for all known forms of life. Its molecules consist of two hydrogen atoms and one oxygen atom. Through its polar nature, it's an excellent solvent for a wide range of substances, impacting countless biological and chemical processes.

Carbon dioxide (\( CO_2 \)) is another common chemical, which is a byproduct of respiration in living organisms and is also utilized by plants during photosynthesis. Table salt, or sodium chloride (\( NaCl \)), encompasses an ionic bond that forms crystals, and is crucial for maintaining fluid balance in living organisms.

Sulfuric acid (\( H_2SO_4 \)), a strong acid used in industry, illustrates a chemical with corrosive properties and the ability to participate in various chemical reactions. The molecular composition and the structure of these examples informs their properties and uses, and understanding these can be instrumental for students in grasping general chemical principles.