1 Angstrom Size

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Scale = 1 Angstrom

[metric scalebar] 1 Å
[ruler]
hydrogen atom
Model of a hydrogen atom.
(© Tom Terry)
Life at the scale of 1 Angstrom (Å)
1 Angstrom is the diameter of a hydrogen atom -- the smallest element. Atoms are the fundamental units from which living organisms are built, and Hydrogen (H) is one of the most abundant elements of living tissue, along with carbon (C), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S). These can be easily remembered by the acronym for their chemical symbols: CHNOPS.

Elsewhere atoms are modeled as colored balls. But at this scale, the components of the atom are represented in a different way.

Hydrogen consists of two fundamental particles, one electron and one proton. The electron is smaller and lighter than the proton, with a mass of only 9.1 x 10-28 gram (about 1/2000 the mass of a proton). The electron, shown here as a moving cloud of red dots, is localized within a spherical probability shell surrounding the proton, the yellow dot at the center. In reality, the proton would be too small to be seen at this resolution.

Most of the atom is empty space. If the hydrogen atom were magnified to the size of Yale Bowl (a stadium seating about 70,000 people), the nucleus could be represented by a basketball on the 50-yard line, and the electron could be represented by a pea whizzing around the outer rows of bleachers. Although still vastly oversimplified, this model is a reasonable analogy for the relative sizes involved.

Physicists and other scientists who work with atoms and molecules prefer to use Angstroms. (Review the Metric System if you are not familiar with this unit.) This way, they can express measurements as single digits rather than as fractions or decimals, which simplifies talking about the relative sizes of atoms and molecules, and the frequencies of radiation.