History of Chemical Elements
This video clearly explains the history of chemical elements. This audiovisual production was produced by PUC Rio in partnership with the Ministry of Education, the Ministry of Science and Technology, and the National Fund for Educational Development.
What is a Chemical Element?
Chemical element is a set made up of atoms that have the same number of protons in their nucleus, that is, the same atomic number (Z). Each element is recognized by a symbol. Gold, for example, has the symbol Au and mercury is Hg.
The Periodic Table contains a vast number of chemical elements. Most elements are found in nature and are known as Natural Elements. Some elements whose atoms are created artificially in laboratories are called Synthetic Elements. The process of creating these elements is known as synthesis.
All chemical elements have an atomic number, atomic mass, melting point (mp), and boiling point (bp). Out of the 118 elements, more than 80 are natural elements and the rest are produced artificially.
Elements are arranged in the Periodic Table in increasing order of their atomic numbers and according to the similarity of their properties (see Period of the Periodic Table).
Symbols of the Chemical Elements
Humans have always tried to identify chemical elements in some way. The alchemists, for example, represented gold with the symbol of the Sun and silver with the symbol of the Moon. Whether the chemical element is natural or synthetic, there is always a symbol attached to it.
Nowadays, the symbols follow international criteria, which allows a chemical element in the Periodic Table to be identified anywhere in the world, regardless of language or alphabet. In other words, the symbols of the chemical elements have become universal.
The standard adopted for choosing the symbols is based on the element’s Latin name, with its initial letter capitalized, followed, if necessary, by a second lowercase letter.
For example, the symbol for Calcium is Ca precisely because there was already another element with the symbol C, in this case Carbon.
The Importance of Chemical Elements in Everyday Life
Chemical elements are absolutely everywhere around us — from the phone you’re using right now to the air you breathe. They are the fundamental building blocks of matter.
A few practical examples:
- Carbon (C): present in everything that is alive, in pencil graphite, and even in fossil fuels.
- Silicon (Si): used in computer chips and solar panels.
- Aluminum (Al): packaging, cans, light and strong structures.
- Chlorine (Cl): drinking water treatment.
- Lithium (Li): essential in rechargeable batteries for phones and electric cars.
Understanding chemical elements is like having a key to decipher the physical world.
Organization of the Periodic Table
The current Periodic Table is a true work of scientific engineering. It was designed to group elements with similar chemical and physical properties while also indicating trends that help predict the behavior of the elements.
The organization follows:
- Periods (horizontal rows): represent electron shells. There are 7 periods.
- Groups or families (vertical columns): gather elements with similar properties. There are 18 groups numbered 1 to 18 (IUPAC) and also known by the A/B letters (such as 1A, 2A…).
Main families:
| Family | Name | Main characteristics |
|---|---|---|
| 1A | Alkali Metals | Extremely reactive, especially with water |
| 2A | Alkaline Earth Metals | Also reactive, but less than 1A |
| 7A | Halogens | Form salts with metals, such as NaCl (table salt) |
| 8A | Noble Gases | Low reactivity, found isolated in nature |
Classification of Elements
Chemical elements can be classified in several ways. The most common are:
1. By physical state at room temperature:
- Solids: the majority of metals (such as Fe, Cu, Zn)
- Liquids: only two — Mercury (Hg) and Bromine (Br)
- Gases: H, N, O, F, Cl and the noble gases
2. By chemical properties:
- Metals: conduct electricity, malleable and ductile
- Nonmetals: poor conductors, brittle in the solid state
- Metalloids (or semimetals): intermediate properties
Chemical Elements and Life
The human body is made up of chemical elements — some in large quantities, others in tiny traces, but all with specific functions.
Main elements in the human body:
| Element | Symbol | Function |
|---|---|---|
| Oxygen | O | Essential for cellular respiration |
| Carbon | C | Basis of all organic molecules |
| Hydrogen | H | Present in water and in organic compounds |
| Nitrogen | N | Present in amino acids and DNA |
| Calcium | Ca | Formation of bones and teeth |
| Phosphorus | P | Formation of DNA and ATP |
| Potassium | K | Nerve impulse conduction |
| Sodium | Na | Cellular fluid balance |
Radioactive Elements
Some elements have unstable nuclei and emit radiation. These are radioactive elements.
Examples:
- Uranium (U): used in nuclear power plants
- Polonium (Po): highly toxic
- Radium (Ra): once used in luminous watches (!)
Radioactivity can be natural (occurs spontaneously) or induced (in the laboratory).
Chemical Elements and Industry
In industry, elements are essential in several areas:
- Electrical engineering: Copper (Cu), Aluminum (Al), Gold (Au)
- Metallurgy: Iron (Fe), Nickel (Ni), Chromium (Cr)
- Agriculture: Nitrogen (N), Phosphorus (P), Potassium (K) — the famous NPK
- Medicine: Iodine (I) in thyroid tests, Technetium (Tc) in imaging scans
The Discovery of the Elements
Many elements were discovered by chance; others through sheer scientific obsession.
- Antiquity: Gold, Silver, Copper, Tin, Iron were already known and used.
- 19th century: major boom with discoveries using techniques such as spectroscopy.
- 20th and 21st centuries: synthetic elements created by nuclear fusion in cutting-edge laboratories.
Today, elements 113 (Nihonium), 114 (Flerovium), 115 (Moscovium), 116 (Livermorium), 117 (Tennessine), and 118 (Oganesson) were the last to be added to the table.
Isotopes, Allotropes and Variants
- Isotopes: atoms of the same element with different numbers of neutrons. Ex: Carbon-12 and Carbon-14 (used in fossil dating)
- Allotropes: different forms of the same element in the pure state. Ex: carbon can form diamond, graphite, and fullerene.
The Most Abundant Elements in the Universe
| Element | Symbol | Approximate abundance (%) |
|---|---|---|
| Hydrogen | H | ~74% |
| Helium | He | ~24% |
| Oxygen | O | ~1% |
| Carbon | C | ~0,5% |
On Earth, the most abundant in the crust are:
- Oxygen (O)
- Silicon (Si)
- Aluminum (Al)
- Iron (Fe)
How to Memorize the Chemical Elements?
Practical tips:
- Use mnemonics to remember groups (e.g., “LiNa K Rb Cs Fr” for the alkali metals)
- Associate elements with objects or everyday situations
- Study in thematic blocks (metals, noble gases, halogens, etc.)
- Use chemistry apps or games such as Quizlet and Ptable
Quick Facts
- Gold is so malleable it can be beaten into a 0.0001 mm sheet.
- Tungsten (W) has the highest melting point among metals: 3,422°C.
- Gallium (Ga) melts in your hand: melting point = 29.7°C.
- Liquid oxygen is blue.
- Iodine (I) is a solid that sublimates, i.e., goes straight to the gaseous state.
Final Conclusion
Studying the chemical elements is not just memorizing names and symbols — it’s about understanding the structure of matter, the basis of everything that exists. From biology to engineering, from medicine to space exploration, everything starts with the Periodic Table.
Knowing the elements means mastering a universal language that spans centuries, cultures, and borders.
📌 Bonus tip for students:
If you’re studying for the ENEM, vestibular, or chemistry exams, first focus on the most common elements (the first 20 in the table) and on the groups with striking properties (such as alkali metals, halogens, and noble gases).