When scientists look closer than a microscope can see at the space between atoms or the length of a chemical bond, they use a tiny unit called the Angstrom. While the Nanometer is the king of nanotechnology, the Angstrom is the king of atomic physics and chemistry.
Converting Angstroms to Nanometers is often required when switching between Chemistry (bonds) and Physics (wavelengths).
This guide covers the history of these units, the simple “divide by 10” rule, and real-world examples from the atomic world.
Definitions and History of Units
What is an Angstrom (A)?
The Angstrom (symbol: Å) is a unit of length equal to one ten-billionth of a meter (10^-10 meters (or 0.0000000001 meters).
- History: It is named after the Swedish physicist Anders Jonas Ångström, one of the founders of spectroscopy. In 1868, he created a chart of the sun’s light spectrum, expressing wavelengths in multiples of one ten-millionth of a millimeter (which later became the Angstrom).
- Usage: It is specifically used in crystallography and chemistry to measure the size of atoms, the lengths of chemical bonds, and the wavelengths of X-rays.
What is a Nanometer (nm)?
The Nanometer is equal to one-billionth of a meter (10^-9 meters, or 0.000000001 meters). It is the standard SI unit for small lengths, but it is 10 times larger than an Angstrom.
The Conversion Formula
The relationship is very simple: 10 Angstroms make 1 Nanometer.
1 Nanometer = 10 Angstroms
To convert from Angstrom to Nanometer, you divide by 10.
Formula:
Nanometers = Angstroms / 10
Manual Calculation Trick
Just move the decimal point one spot to the left.
- Example: 15 Angstroms (size of a small protein).
- Process: Move the decimal left once (15.0 -> 1.5).
- Result: 1.5 nm.
Real-Life Examples
- The Hydrogen Atom: The diameter of a hydrogen atom is roughly 1 Angstrom.
- Calculation: 1 / 10 = 0.1 nanometers.
- DNA Helix: The width of a DNA double helix is 20 Angstroms.
- Calculation: 20 / 10 = 2.0 nanometers.
- Silicon Crystal: The lattice spacing of silicon is 5.43 Angstroms.
- Calculation: 5.43 / 10 = 0.543 nanometers.
Quick Reference Table: Angstrom to nm
| Angstroms (A) | Nanometers (nm) | Real-Life Context |
| 1 A | 0.1 nm | Diameter of Hydrogen atom |
| 5 A | 0.5 nm | Width of a small molecule |
| 10 A | 1.0 nm | The “Nano” boundary |
| 20 A | 2.0 nm | Diameter of a DNA helix |
| 100 A | 10.0 nm | Thickness of a cell membrane |
Frequently Asked Questions (FAQ)
1. Is an Angstrom an official SI unit?
No. The Angstrom is not part of the official International System of Units (SI). However, it is so useful in chemistry and crystallography that it is still widely used and accepted alongside SI units.
2. How do I type the Angstrom symbol?
The symbol Å (A with a circle on top) is hard to type. Most people just write “Angstroms” or “A”. On a PC, you can sometimes use Alt + 0197.
3. Why do chemists prefer Angstroms?
Because most chemical bonds are between 1 and 3 Angstroms long. It is easier to say “1.5 Angstroms” than “0.15 Nanometers.”
4. How many Angstroms are in a Micrometer?
There are 10,000 Angstroms in one Micrometer.
5. What is the difference between A and nm?
It is just a decimal point shift. Angstroms are smaller. If you have 50 Angstroms, you only have 5 Nanometers.
References
- NIST (National Institute of Standards and Technology): Guide for the Use of the International System of Units (SI).
- IUPAC (International Union of Pure and Applied Chemistry): Compendium of Chemical Terminology (“Gold Book”).