This detailed guide includes the first 20 elements of the periodic table with their names, symbols, atomic numbers, valency, and atomic masses. Perfect for students and science enthusiasts to understand the building blocks of matter.
| Atomic Number | Element | Symbol | Atomic Mass (approx.) | Valency |
|---|---|---|---|---|
| 1 | Hydrogen | H | 1.008 | 1 |
| 2 | Helium | He | 4.0026 | 0 |
| 3 | Lithium | Li | 6.94 | 1 |
| 4 | Beryllium | Be | 9.01 | 2 |
| 5 | Boron | B | 10.81 | 3 |
| 6 | Carbon | C | 12.01 | 4 |
| 7 | Nitrogen | N | 14.01 | 3 |
| 8 | Oxygen | O | 16 | 2 |
| 9 | Fluorine | F | 19 | 1 |
| 10 | Neon | Ne | 20.18 | 0 |
| 11 | Sodium | Na | 22.99 | 1 |
| 12 | Magnesium | Mg | 24.31 | 2 |
| 13 | Aluminium | Al | 26.98 | 3 |
| 14 | Silicon | Si | 28.09 | 4 |
| 15 | Phosphorus | P | 30.97 | 3 |
| 16 | Sulphur | S | 32.06 | 2 |
| 17 | Chlorine | Cl | 35.45 | 1 |
| 18 | Argon | Ar | 39.95 | 0 |
| 19 | Potassium | K | 39.1 | 1 |
| 20 | Calcium | Ca | 40.08 | 2 |
The atomic number of an element provides information about the number of protons present in the nucleus of its atoms and the number of electrons that orbit these nuclei. For instance, sodium has an atomic number of 11, which means that a sodium atom's nucleus contains 11 protons and is encircled by 11 electrons. As the atomic number of an atom equals the number of its electrons, we can determine the electronic configuration of an element just by knowing its atomic number.
It's crucial to understand that an atom's atomic number doesn't determine the number of neutrons in its nucleus. Different isotopes of an element may have the same number of protons and electrons (since they have the same atomic number) but varying numbers of neutrons. For instance, a sodium atom can have 11, 12, or 13 neutrons (depending on the isotope) but will always have 11 protons and 11 electrons.
The symbol 'K' represents potassium, which comes from its medieval Latin name 'Kalium'. Similarly, the symbol for sodium is 'Na', which represents its older name 'Natrium'. Several other elements have symbols that represent their old names. Here are a few examples:
The first 20 elements in the periodic table are Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulphur, Chlorine, Argon, Potassium, and Calcium.
Element symbols are one or two-letter abbreviations for chemical elements (e.g., H for Hydrogen), and atomic numbers represent the number of protons in an atom of that element.
Atomic mass refers to the mass of an element's atom, typically measured in atomic mass units (amu). It generally includes the total number of protons and neutrons in the nucleus.
These elements form the foundation of basic chemistry. They illustrate fundamental principles such as electron configuration, bonding, and periodic trends.
They are arranged by increasing atomic number from left to right, and elements with similar properties are placed in the same groups or columns.
Metals among the first 20 elements include Lithium, Beryllium, Sodium, Magnesium, Aluminium, Potassium, and Calcium. Non-metals include Hydrogen, Carbon, Nitrogen, Oxygen, Fluorine, Phosphorus, Sulphur, and Chlorine. Helium, Neon, and Argon are noble gases. Silicon and Boron are considered metalloids.
Hydrogen has 1 electron, Helium has 2, Lithium has 3, Beryllium has 4, and Boron has 5.
Noble gases (Helium, Neon, Argon) do not typically form compounds easily due to their stable, complete outer electron shells.
There are three noble gases in the first 20 elements: Helium (He) with atomic number 2, Neon (Ne) with atomic number 10, and Argon (Ar) with atomic number 18.
The modern periodic table consists of 7 periods. Each period corresponds to the number of electron shells in an atom of the elements in that row.