Chemistry within the Canon of the Natural Sciences

Chemistry as a Natural Science

Chemistry is one of the central natural sciences, alongside physics, biology, earth sciences, and astronomy. It focuses on the composition, structure, properties, and transformations of matter. Within the canon of the natural sciences, chemistry both builds upon other sciences and provides them with essential concepts and tools.

This chapter clarifies where chemistry is positioned among the natural sciences, how it connects to them, and what is specific about a “chemical way” of looking at the world.

The Object of Chemistry: Matter and Its Transformations

All natural sciences deal with nature, but they ask different kinds of questions.

In chemistry, the central questions are:

• What substances is matter made of?
• How are the smallest particles of a substance arranged and bonded?
• How and why do substances change into other substances?
• How can we control and use these changes?

Typical chemical topics include:

• Identifying substances (e.g. “What is in this sample?”).
• Understanding composition (e.g. “Which elements and in what ratio?”).
• Investigating reactions (e.g. “What forms when iron rusts?”).
• Relating structure to properties (e.g. “Why is diamond hard but graphite soft, although both are carbon?”).

While physics often focuses on general laws of motion, forces, and energy, chemistry is particularly concerned with specific substances and the changes in their composition.

Chemistry Between Physics and Biology

Chemistry occupies a “middle position” between physics and biology:

• From physics, chemistry draws:
• The concept of atoms, nuclei, and electrons.
• Ideas about energy, forces, and fields.
• Models that explain bonding and structure of matter.
• For biology, chemistry provides:
• The molecular basis of life (DNA, proteins, lipids, carbohydrates).
• Explanations of metabolic pathways and energy conversion in cells.
• Tools for studying and influencing biological systems (e.g. drugs, biochemical assays).

Because of this bridging role, chemistry is sometimes described as the “central science”: it links the microscopic world of atoms and molecules with the macroscopic phenomena studied in other natural sciences.

Levels of Description in Chemistry

One key feature of chemistry is the use of different levels of description, which must be clearly distinguished:

1. Macroscopic level
   Observable phenomena using our senses or simple instruments:
• Color changes, precipitate formation, gas evolution, temperature change.
• For example: iron rusting, ice melting, sugar dissolving.
2. Submicroscopic (particle) level
   Processes involving atoms, ions, and molecules:
• Rearrangement of atoms in a chemical reaction.
• Formation and breakage of chemical bonds.
3. Symbolic level
   Use of formulas, equations, and diagrams:
• Chemical formulas like $ \mathrm{H_2O} $, $ \mathrm{NaCl} $.
• Structural formulas and reaction equations.

Chemistry constantly switches between these levels: a visible color change (macroscopic) is interpreted in terms of molecular changes (submicroscopic) and represented by symbols and equations (symbolic). This multilevel perspective distinguishes chemical thinking within the natural sciences.

Boundaries and Overlaps with Neighboring Sciences

Although each natural science has its own focus, the boundaries are not sharp. Many fields lie at the intersection of chemistry with other disciplines:

• With physics (physical chemistry, chemical physics)
• Study of reaction rates, energy changes, and molecular motion.
• Spectroscopy: interaction of light with matter.
• Quantum descriptions of bonds and structures.
• With biology (biochemistry, molecular biology)
• Chemical processes in living systems: metabolism, photosynthesis, respiration.
• Structure and function of biomolecules (DNA, proteins, membranes).
• With earth sciences (geochemistry, environmental chemistry)
• Composition of rocks, soils, oceans, and atmosphere.
• Cycles of elements such as carbon, nitrogen, and sulfur.
• Chemical aspects of environmental pollution and remediation.
• With materials science (polymer chemistry, inorganic materials)
• Development of plastics, ceramics, metals, and composites.
• Relationship between composition, structure, and material properties.

At these interfaces, chemical methods and concepts are applied to questions originally posed in other sciences, which underlines the integrative role of chemistry.

Chemistry as an Experimental Science

Like all natural sciences, chemistry relies on observation and experiment. Its experimental character shows up in particular ways:

• Substances are prepared, purified, and transformed in the laboratory.
• Conditions such as temperature, pressure, concentration, and catalysts are systematically varied.
• Quantities such as mass, volume, and composition are measured to reveal relationships between substances and reactions.

What is typical for chemistry is the emphasis on manipulating matter: chemists not only observe natural processes but also deliberately produce new substances and materials, often ones that do not occur in nature.

The detailed procedures for planning, carrying out, and evaluating experiments, as well as the specific ways of thinking and working in chemistry, are developed further in later chapters.

The Role of Models and Abstractions

Chemistry deals with entities that cannot be directly seen, such as atoms and molecules. To make this world accessible, chemistry relies strongly on models and abstractions:

• Particle models of matter to explain states (solid, liquid, gas) and mixing.
• Structural formulas to represent the connectivity of atoms.
• Simplified pictures of atoms and bonds to reason about reactivity.

These models do not claim to show “how things really look,” but they help organize observations and make predictions. Chemistry thus contributes to the general scientific practice of using models: it offers concrete, often visual, tools that are widely used in other sciences as well (for example, molecular models in biology).

Chemistry in the System of Human Knowledge

Within the broader system of human knowledge, chemistry belongs to the empirical sciences: it builds knowledge through systematic observation, measurement, and experiment. Its place in this system can be characterized by several features:

• Empirical foundation
  Concepts and theories must be consistent with experimental findings.
• Quantitative orientation
  Many chemical questions are expressed and answered numerically (e.g. yields, concentrations, reaction rates).
• Applied relevance
  Chemistry underpins numerous technologies and industries:
• Pharmaceuticals and medicine.
• Energy conversion and storage.
• Agriculture (fertilizers, pesticides).
• Materials and consumer products.
• Ethical and societal dimension
  The production and use of chemicals affect health and the environment. Understanding chemistry is therefore important for informed participation in social debates on topics such as pollution, climate change, and sustainable resource use.

In this way, chemistry is not an isolated discipline but part of a network of sciences that together aim to understand nature and to use this understanding responsibly.

Summary of Chemistry’s Position Among the Natural Sciences

• Chemistry investigates matter and its transformations, with special attention to the composition and structure of substances.
• It connects physics (fundamental laws and particles) with biology (structures and processes in living systems), and interacts closely with earth sciences and materials science.
• Chemical thinking operates on macroscopic, submicroscopic, and symbolic levels and moves flexibly between them.
• As an experimental and model-based science, chemistry not only explains natural phenomena but also enables the targeted design of new substances and materials.
• Within the canon of natural sciences, chemistry plays a central, linking role and contributes decisively to technological progress and societal development.