Chemistry is a fundamental discipline in the world of science. This science is dedicated to the study of matter, its composition, structure, properties and transformations. Throughout history, chemistry has played a crucial role in humanity's understanding and advancement in areas ranging from medicine and industry to technology and energy.
In this section, we will address topics related to chemistry: its basic concepts, the main branches of this discipline and some of the fundamental laws that govern this science.
What is chemistry?
Chemistry is the science that studies matter and how the atoms and molecules that make it up interact. Matter is everything that surrounds us: the air we breathe, the water we drink, the food we consume and the materials that make up our environment. Chemistry seeks to understand the structure of matter at the molecular level and how it behaves under various conditions.
One of the key concepts in chemistry is that of the atom. Atoms are the smallest units of a chemical element and consist of a central nucleus of protons and neutrons, surrounded by orbiting electrons. The combination of different types of atoms gives rise to the formation of molecules and chemical compounds.
Basic concepts of chemistry
The study of chemistry is associated with a large number of names and concepts.
The most important basic concepts are the following:
Chemical elements and compounds
Chemical elements are substances that consist of a single type of atom, such as oxygen (O) or hydrogen (H). The elements are found on the periodic table, which lists all known elements and organizes their properties systematically.
Compounds, on the other hand, are formed by the combination of two or more elements in defined proportions. For example, water (H2O) is a compound made up of two hydrogen atoms and one oxygen atom.
Chemical reactions
Chemical reactions are processes in which bonds between atoms are broken and new bonds are formed, leading to the creation of new substances. In a chemical equation, the reactants are represented on the left and the products on the right.
For example, the combustion of methane is represented as:
CH4 (methane) + 2O2 (oxygen) → CO2 (carbon dioxide) + 2H2O (water)
States of the material
Matter can exist in three main states: solid, liquid and gas. These states depend on the kinetic energy of the particles that make up the matter.
In the solid state, the particles are very close to each other and have low kinetic energy. In the liquid state, the particles are further apart and have moderate kinetic energy. Finally, in the gaseous state, the particles are separated and have high kinetic energy.
Main branches of chemistry
Chemistry is a broad discipline that is divided into several main branches, each of which focuses on specific aspects of chemical science:
1. Inorganic chemistry
Inorganic chemistry is concerned with the study of chemical compounds that do not contain carbon-hydrogen (CH) bonds. This includes elements such as metals, minerals, and inorganic compounds.
Inorganic chemistry is fundamental in industry, metallurgy and the synthesis of materials.
2. Organic chemistry
Organic chemistry focuses on the study of compounds containing carbon-hydrogen (CH) bonds, including hydrocarbons and a wide variety of organic compounds.
This branch is essential in the manufacture of chemicals, drugs and the synthesis of organic materials.
3. Physical chemistry
Physical chemistry investigates the physical and mathematical principles that govern chemical reactions and the properties of matter. This branch includes thermodynamics, chemical kinetics and spectroscopy.
4. Analytical chemistry
Analytical chemistry is dedicated to the identification and quantification of chemicals in samples. It uses techniques such as spectroscopy and chromatography to perform qualitative and quantitative analysis.
5. Biochemistry
Biochemistry is a scientific discipline that is located at the intersection between biology and chemistry. It focuses on the study of the molecules and chemical reactions that support life in organisms.
Biochemistry investigates how biomolecules, such as proteins, nucleic acids, lipids and carbohydrates, interact and participate in fundamental biological processes, such as protein synthesis, DNA replication and obtaining energy through cellular respiration and photosynthesis.
6. Synthetic organic chemistry
Synthetic organic chemistry focuses on the synthesis and creation of new organic compounds for applications in the manufacturing of chemicals, drugs, and advanced materials.
7. Synthetic inorganic chemistry
Synthetic inorganic chemistry is similar to synthetic organic chemistry, but focuses on the synthesis of inorganic compounds and materials, including transition metals and advanced materials.
Fundamental laws of chemistry
Chemistry is governed by a series of fundamental laws that describe how atoms and molecules interact.
Some of the most important laws include:
1. Law of conservation of mass
The law of conservation of mass states that the total mass of the reactants in a chemical reaction is equal to the total mass of the products. In other words, matter is neither created nor destroyed, it only transforms.
2. Law of definite proportions
The law of definite proportions holds that elements always combine in fixed, defined proportions by mass when they form chemical compounds. This means that a given chemical compound always has the same ratio of atoms.
3. Law of multiple proportions
The law of multiple proportions states that when two elements form more than one chemical compound, the masses of one of the elements that combine with a fixed mass of the other element are in simple, whole proportions.
4. Law of conservation of energy
The law of conservation of energy (which is included in the first law of thermodynamics) states that energy is neither created nor destroyed, it is only transformed from one form to another.
In chemical reactions, energy can be converted from one form to another, such as from kinetic energy to potential energy.
5. Avogadro's Law
Avogadro's law states that equal volumes of gases at the same temperature and pressure contain the same number of molecules. This is essential for calculating quantities of substances in chemistry.