1 nanometre (nm) is equal to 10⁻⁹ metres (one billionth of a metre). The nanometre is a unit of length in the SI metric system. The prefix 'nano' means 10⁻⁹. Nanometres are used to measure extremely small distances — the size of atoms, molecules, viruses, and the wavelength of visible light. For example, the diameter of a DNA double helix is about 2 nm, the wavelength of visible light ranges from 400 to 700 nm, and the radius of a hydrogen atom is about 0.053 nm.
1 nm = 10⁻⁹ metres (one billionth of a metre).
1 nm = 10 Å (angstroms); 1 Å = 10⁻¹⁰ m.
1 nm = 1000 pm (picometres); 1 pm = 10⁻¹² m.
1 nm = 10⁻³ μm (micrometre/micron); 1 μm = 1000 nm.
The prefix 'nano' means 10⁻⁹.
Visible light wavelength: 400–700 nm.
DNA double helix width: ~2 nm.
Hydrogen atom radius (Bohr radius): ~0.053 nm = 0.53 Å.
Modern computer chip transistors are 2–7 nm in size.
1 nm in other units:
Unit | Equivalent to 1 nm Metres (m) | 1 × 10⁻⁹ m = 0.000000001 m Centimetres (cm) | 1 × 10⁻⁷ cm Millimetres (mm) | 1 × 10⁻⁶ mm Micrometres/microns (μm) | 1 × 10⁻³ μm = 0.001 μm Angstroms (Å) | 10 Å Picometres (pm) | 1000 pm Femtometres (fm) | 1,000,000 fm = 10⁶ fm
Reverse conversions: • 1 m = 10⁹ nm (one billion nanometres) • 1 cm = 10⁷ nm • 1 mm = 10⁶ nm • 1 μm (micron) = 1000 nm • 1 Å (angstrom) = 0.1 nm • 1 pm (picometre) = 0.001 nm
Key relationships to memorise: • 1 nm = 10 Å (angstroms) — often used in atomic spectroscopy and chemistry • 1 nm = 1000 pm (picometres) — used for very small measurements like nuclear radii • 1 μm = 1000 nm — micron to nanometre
Nanometres are the unit of choice for measuring objects at the atomic and molecular scale:
Biological structures: • DNA double helix width: ~2 nm • Protein size: 1–10 nm • Ribosome diameter: ~20–30 nm • Virus size: 20–300 nm • Bacterium (E. coli): ~1000–2000 nm = 1–2 μm • Red blood cell: ~6000–8000 nm = 6–8 μm (larger — usually measured in μm)
Atomic/molecular scale: • Hydrogen atom radius (Bohr radius): 0.053 nm = 0.53 Å • Carbon atom covalent radius: ~0.077 nm • C–H bond length: ~0.109 nm • Water molecule diameter: ~0.28 nm
Light (electromagnetic radiation): • Visible light wavelength: 400–700 nm — Violet: 380–450 nm — Blue: 450–495 nm — Green: 495–570 nm — Yellow: 570–590 nm — Orange: 590–620 nm — Red: 620–750 nm • UV light: <400 nm • Near infrared: 750–2500 nm
Nanotechnology: • Computer chip transistor size: 2–7 nm (modern chips, as of 2024) • Gold nanoparticles: 1–100 nm
In chemistry: • Bond lengths are typically measured in angstroms (Å) or picometres (pm), but nanometres are also used • Colloidal particles: 1–1000 nm (Tyndall effect is visible in this range) • Nanoparticles: 1–100 nm — have very different properties from bulk material • Drug delivery nanoparticles: 20–200 nm
In physics: • Wavelength of visible light (400–700 nm) — important for optics, spectroscopy, lasers • De Broglie wavelength of electrons: ~0.1–1 nm for typical electron microscopy beams • Electron microscope resolution: ~0.1 nm — can image individual atoms • X-ray wavelengths: 0.01–10 nm
Nanotechnology uses nanometre-scale structures to create materials and devices with unique properties: • Carbon nanotubes: ~1–100 nm diameter • Graphene: one atom thick (0.34 nm)
1 nanometre (nm) = 10⁻⁹ metres = 0.000000001 metres. The prefix 'nano' means 10⁻⁹, so 1 nm is one billionth of a metre. In other words, 1 metre = 10⁹ nm = one billion nanometres.
1 nm = 10 angstroms (Å). This is because 1 Å = 10⁻¹⁰ m and 1 nm = 10⁻⁹ m. So 1 nm = 10⁻⁹ / 10⁻¹⁰ = 10 Å. Angstroms are commonly used in chemistry and crystallography to express atomic and bond sizes.
1 nm = 1000 pm (picometres). This is because 1 pm = 10⁻¹² m and 1 nm = 10⁻⁹ m. So 1 nm = 10⁻⁹ / 10⁻¹² = 10³ = 1000 pm.
Visible light has wavelengths ranging from about 400 nm (violet) to 700 nm (red): Violet: 380–450 nm, Blue: 450–495 nm, Green: 495–570 nm, Yellow: 570–590 nm, Orange: 590–620 nm, Red: 620–750 nm. Ultraviolet (UV) is below 400 nm; infrared is above 700 nm.
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