The Periodic Table of Elements – Introduction and Discoveries

The Periodic Table of Elements (PTE) is a systematic arrangement of all known chemical elements. It was developed to organize the elements according to their properties and atomic structure.
Each box stands for an element, shown by a symbol (for example H for hydrogen), an atomic number, and atomic mass.
The periodic table helps us easily recognize similarities and differences between chemical elements.
The placement of elements follows specific rules based on the structure of their atoms and their properties. The periodic table is like the map of chemistry and is indispensable for science.
⚙ einfuhrung

The periodic table is divided into groups (columns, from top to bottom) and periods (rows, from left to right).
- Groups: Elements in a group share similar chemical properties because they have the same number of outer electrons (valence electrons). There are 18 main groups, e.g., the alkali metals (group 1) or noble gases (group 18).
- Periods: Elements in a period have the same number of electron shells. From left to right, the atomic number increases, as does the nucleus size.

Term	Meaning	Example
Group	same valence electrons, similar reactions	Group 17: Halogens (e.g. chlorine)
Period	same number of electron shells	3rd period: sodium to argon

This creates horizontal and vertical relationships in the PTE, helping predict many properties of the elements.
⚙ aufbau

Hydrogen (H, from Latin "Hydrogenium", atomic number 1) is the first and lightest element in the periodic table.
It consists of only one proton and one electron and is colorless and odorless.
Properties & Uses:
- Hydrogen is extremely light and is the most common element in the universe.
- Combined with oxygen, it forms water (H₂O).
- Its gas is used as an energy source for fuel cells, e.g., in hydrogen-powered cars.
- In space technology, hydrogen is used as rocket fuel.
Hydrogen also plays a main role in processes like energy production in the Sun (nuclear fusion). In the laboratory, hydrogen is important for many chemical reactions.
⚙ wasserstoff

Oxygen (O, from Latin "Oxygenium", atomic number 8) is the second most abundant element in the Earth's crust and is essential for nearly all living beings.
Important Properties:
- Oxygen is a colorless and odorless gas, making up about 21% of the air.
- Essential for the respiration of humans and animals.
- Enables energy production in cells (cellular respiration).
- Water contains about one third oxygen.
Uses:
- In medicine, pure oxygen is used for breathing problems.
- Industrially, it is crucial for steel production in blast furnaces.
- Oxygen is vital for combustion processes and life on Earth.
⚙ sauerstoff

Iron (Fe, from Latin "Ferrum", atomic number 26) is one of the most important metals for technology and humans.
Properties:
- Iron is hard, strong, and malleable.
- It rusts (forms iron oxide) when reacting with oxygen and water.
- Magnetic – iron attracts magnets.
Uses:
- Main component of steel, used for buildings, tools, and machines.
- Iron is essential for our bodies: it transports oxygen in the blood (part of hemoglobin).
- Found in many everyday items such as nails, pans, and bridges.
Without iron, our civilization would be almost unimaginable.
⚙ eisen

The periodic table is not just an overview – it connects and explains the world of chemistry.
Advantages and Benefits:
- Chemical reactions and compounds can be predicted.
- New elements are classified according to the rules of the PTE.
- It helps in research, technology, and everyday life (materials, medicines, energy production).
For beginners in chemistry, the PTE is the key to discovering the fascinating structure of matter.
⚙ vorteile