What Are the First 20 Elements – Names and Symbols

Here are the names, element symbols, and atomic numbers of the first 20 elements of the periodic table.
Here are the names, element symbols, and atomic numbers of the first 20 elements of the periodic table.

It’s handy to know the first 20 elements of the periodic table. Around 99% of the mass of the human body is made of six of these elements. The first 20 elements are also a good overview of the different element groups. They also occur in most everyday chemical reactions.

List of the First 20 Elements

The elements are listed in order of increasing atomic number. The atomic number is the number of protons in atoms of each element. The first 20 elements and their symbols are:

  1. Hydrogen (H)
  2. Helium (He)
  3. Lithium (Li)
  4. Beryllium (Be)
  5. Boron (B)
  6. Carbon (C)
  7. Nitrogen (N)
  8. Oxygen (O)
  9. Fluorine (F)
  10. Neon (Ne)
  11. Sodium (Na)
  12. Magnesium (Mg)
  13. Aluminum (Al)
  14. Silicon (Si)
  15. Phosphorus (P)
  16. Sulfur (S)
  17. Chlorine (Cl)
  18. Argon (Ar)
  19. Potassium (K)
  20. Calcium (Ca)

What Makes Them Elements?

At a minimum, matter must contain one or more protons to be an element. The number of protons identifies the element. Atoms of elements may also contain neutrons together with protons to form the atomic nucleus. Samples with the same number of protons but different numbers of neutrons are all the same element but are different isotopes. Atoms also have electrons that orbit around the nucleus. Changing the number of electrons around an atom makes it an ion, but doesn’t change its identity as an element. Elements are called the building blocks of matter because their atoms can’t be divided into smaller parts using any chemical means. Atoms of elements can form chemical bonds with one another to form compounds.

Element Names and Symbols

Elements may be identified using their atomic number, element name, or element symbol. The symbol is a one- or two-letter abbreviation of the name. However, some symbols refer to old element names. For example, the symbol for sodium is Na. This refers to the Latin word natrium, which was the old name for caustic soda. The symbol of potassium is K, which stands for the Latin word kalium, which meant alkali or potash. The first letter of an element symbol is capitalized. When there is a second letter, it is lower case.

Vivid Color Periodic Table Wallpaper 1920x1080

The Element Song

Now that you know the first 20 elements, why not learn the names of several more? Try singing “The Element Song” or follow along!

A Closer Look at the First 20 Elements

Here is a brief description of each of the first 20 elements, including appearance, state of matter under normal temperature and pressure, atomic number, symbol, atomic mass, electron configuration, and element group:

NGC 604, a region of ionized hydrogen in the Triangulum Galaxy. Hubble Space Telescope
Hydrogen is the first element and is the most abundant one in the universe.
  • Hydrogen is a nonmetallic, colorless gas under ordinary conditions. Under extreme pressure, it becomes an alkali metal. There are three isotopes of this element, which differ in the number of neutrons in their atoms. The most common isotope is protium. The others are deuterium and tritium.
  • Atomic Number: 1
  • Symbol: H
  • Atomic Mass: 1.008
  • Electron Configuration: 1s1
  • Group: group 1, s-block, nonmetal
  • Helium is a light, colorless gas.
  • Atomic Number: 2
  • Symbol: He
  • Atomic Mass: 4.002602(2)
  • Electron Configuration: 1s2
  • Group: group 18, s-block, noble gas
Lithium is the 3rd of the first 20 elements.
Lithium is a highly reactive metal.
  • Lithium is a reactive silver solid metal.
  • Atomic Number: 3
  • Symbol: Li
  • Atomic Mass: 6.94 (6.938–6.997)
  • Electron Configuration: [He] 2s1
  • Group: group 1, s-block, alkali metal
  • Beryllium is a shiny gray-white solid metal.
  • Atomic Number: 4
  • Symbol: Be
  • Atomic Mass: 9.0121831(5)
  • Electron Configuration: [He] 2s2
  • Group: group 2, s-block, alkaline earth metal
  • Boron is a gray solid with a metallic luster.
  • Atomic Number: 5
  • Symbol: B
  • Atomic Mass: 10.81 (10.806–10.821)
  • Electron Configuration: [He] 2s2 2p1
  • Group: group 13, p-block, metalloid
  • Carbon is a solid that takes several forms, include diamond, graphite, and amorphous carbon. It is black, gray, or colorless.
  • Atomic Number: 6
  • Symbol: C
  • Atomic Mass: 12.011 (12.0096–12.0116)
  • Electron Configuration: [He] 2s2 2p2
  • Group: group 14, p-block, usually a nonmetal although sometimes considered a metalloid
  • Nitrogen is a colorless gas.
  • Atomic Number: 7
  • Symbol: N
  • Atomic Mass: 14.007
  • Electron Configuration: [He] 2s​2 2p3
  • Group: group 15 (pnictogens), p-block, nonmetal
  • Oxygen is a colorless gas. Its liquid form is blue, while its solid takes many colors, including red, metallic, and black.
  • Atomic Number: 8
  • Symbol: O
  • Atomic Mass: 15.999 or 16.00
  • Electron Configuration: [He] 2s2 2p4
  • Group: group 16 (chalcogens), p-block, nonmetal
  • Fluorine is a pale yellow gas and liquid and bright yellow solid.
  • Atomic Number: 9
  • Symbol: F
  • Atomic Mass: 18.998403163(6)
  • Electron Configuration: [He] 2s2 2p5
  • Group: group 17, p-block, halogen
  • Neon is a colorless gas that emits an orange-red glow when excited in an electric field.
  • Atomic Number: 10
  • Symbol: Ne
  • Atomic Mass: 20.1797(6)
  • Electron Configuration: [He] 2s2 2p6
  • Group: group 18, p-block, noble gas
  • Sodium is a soft, silvery-white solid metal.
  • Atomic Number: 11
  • Symbol: Na
  • Atomic Mass: 22.98976928(2)
  • Electron Configuration: [Ne] 3s1
  • Group: group 1, s-block, alkali metal
  • Magnesium is a shiny gray solid metal.
  • Atomic Number: 12
  • Symbol: Mg
  • Atomic Mass: 24.305
  • Electron Configuration: [Ne] 3s2
  • Group: group 2, s-block, alkaline earth metal
  • Aluminum is a soft, silver-colored, nonmagnetic metal.
  • Atomic Number: 13
  • Symbol: Al
  • Atomic Mass: 26.9815385(7)
  • Electron Configuration: [Ne] 3s2 3p1
  • Group: group 13, p-block, considered a post-transition metal or sometimes a metalloid
  • Silicon is a hard, blue-gray crystalline solid that has a metallic luster.
  • Atomic Number: 14
  • Symbol: Si
  • Atomic Mass: 28.085
  • Electron Configuration: [Ne] 3s2 3p2
  • Group: group 14 (carbon group), p-block, metalloid
  • Phosphorus is a solid under ordinary conditions, but it takes several forms. The most common are white phosphorus and red phosphorus.
  • Atomic Number: 15
  • Symbol: P
  • Atomic Mass: 30.973761998(5)
  • Electron Configuration: [Ne] 3s2 3p3
  • Group: group 15 (pnictogens), p-block, usually considered a nonmetal, but sometimes a metalloid
Sulfur Crystals
Sulfur is a yellow nonmetal.
  • Sulfur is a yellow solid, usually found as a crystal or powder.
  • Atomic Number: 16
  • Symbol: S
  • Atomic Mass: 32.06
  • Electron Configuration: [Ne] 3s2 3p4
  • Group: group 16 (chalcogens), p-block, nonmetal
  • Chlorine is a pale yellow-green gas under ordinary conditions. Its liquid form is bright yellow.
  • Atomic Number: 17
  • Symbol: Cl
  • Atomic Mass: 35.45
  • Electron Configuration: [Ne] 3s2 3p5
  • Group: group 17, p-block, halogen
  • Argon is a colorless gas, liquid, and solid. It is a gas under ordinary conditions. It emits a bright lilac-purple glow when excited in an electric field.
  • Atomic Number: 18
  • Symbol: Ar
  • Atomic Mass: 39.948(1)
  • Electron Configuration: [Ne] 3s2 3p6
  • Group: group 18, p-block, noble gas
  • Potassium is a reactive, silvery solid metal.
  • Atomic Number: 19
  • Symbol: K
  • Atomic Mass: 39.0983(1)
  • Electron Configuration: [Ar] 4s1
  • Group: group 1, s-block, alkali metal
  • Calcium is a dull silver solid metal with a faint yellowish cast.
  • Atomic Number: 20
  • Symbol: Ca
  • Atomic Mass: 40.078(4)
  • Electron Configuration: [Ar] 4s2
  • Group: group 2, s-block, alkaline earth metal


  • Ball, P. (2004). The Elements: A Very Short Introduction. Oxford University Press. ISBN 978-0-19-284099-8.
  • Emsley, J. (2003). Nature’s Building Blocks: An A–Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-850340-8.
  • Gray, T. (2009). The Elements: A Visual Exploration of Every Known Atom in the Universe. Black Dog & Leventhal Publishers Inc. ISBN 978-1-57912-814-2.
  • IUPAC (1997). “Chemical Element.” Compendium of Chemical Terminology (2nd ed.). doi:10.1351/goldbook.C01022