Atoms in a Grain of Sand ✅ Compared

Because atoms are so tiny, you'll often hear people use comparisons by saying things like "There are more atoms in a grain of sand than ___", which reminds us of the remarkable scale of things at the atomic level.  But how factual and true are these statements? What interesting and mind boggling things do contain more or less of something than the number of atoms in a grain of sand?

Well, I decided to do a little research and have condensed the facts related to what was found, here. So if you're wondering, read along to find out.
atoms in a grain of sand
A single grain of sand is small but still visible to the naked eye, averaging .1mm (a tenth of a millimeter) in size or between 0.06mm to 2.0mm. Atoms on the other hand, are so extremely small that they cannot be seen with the naked eye. Atoms average .3nm (about a third of a nanometer) in size or between 0.1nm to 0.5nm.

How many Atoms in a grain of Sand?

Estimating the number of atoms in a grain of sand depends on its size, composition, and density. However, we can find a rough estimation for a grain of sand with a diameter of 0.1 millimeters (mm) using some assumptions and calcuations.

Assumed specifications of a single grain of sand:

  1. Size of the Grain: A single grain of sand with a diameter of 0.1 mm.
  2. Composition: Sand is primarily composed of silicon dioxide (SiO2), which consists of silicon (Si) and oxygen (O) atoms.
  3. Density: The density of sand can vary, but it's often around 2.65 grams per cubic centimeter (g/cm³).

Now, let's make some calculations:

  1. First, calculate the volume of the grain of sand. Assuming it's roughly spherical, you can use the formula for the volume of a sphere: V = (4/3)πr^3, where r is the radius.
    • Radius (r) = 0.1 mm / 2 = 0.05 mm = 0.005 cm
    • Volume (V) = (4/3)π(0.005 cm)^3 ≈ 5.24 x 10^-7 cm³
  2. Next, calculate the mass of the grain of sand using its volume and density:
    • Mass (m) = Volume (V) x Density ≈ (5.24 x 10^-7 cm³) x (2.65 g/cm³) ≈ 1.39 x 10^-6 grams
  3. Now, let's estimate the number of silicon atoms in this grain of sand. Silicon has an atomic mass of roughly 28.09 atomic mass units (AMU). One mole of silicon atoms (6.022 x 10^23 atoms) has a mass of 28.09 grams.
    • Number of moles of silicon in the grain of sand = Mass (m) / Atomic mass of silicon ≈ (1.39 x 10^-6 g) / (28.09 g/mol) ≈ 4.94 x 10^-8 moles
  4. Finally, you can calculate the number of silicon atoms in the grain of sand:
    • Number of silicon atoms ≈ Number of moles x Avogadro's number ≈ (4.94 x 10^-8 moles) x (6.022 x 10^23 atoms/mole) ≈ 2.98 x 10^16 silicon atoms.

This means that for a 0.1 mm grain of sand, there might be 2.98 x 10^16 silicon atoms. The number 2.98 x 10^16 represents 29,800,000,000,000,000 silicon atoms. So it can be said that there are approximately "29.8 quadrillion atoms in a single .1mm grain of sand".

Keep in mind that this is a rough estimate, and the actual number can vary depending on the specific type of sand and its exact composition.

Atoms in a Grain of Sand | Compared to what

At first glance, a grain of sand may seem like a tiny, unremarkable speck, but within it lies a multitude of atoms. But we previously learned that there are approximately 29.8 quadrillion atoms in a single grain of sand. While a grain of sand contains a substantial number of atoms, the true marvel of the atomic world becomes evident when we begin to explore and compare the composition of nature, everyday objects, and the universe to the atomic count of a grain of sand.

Similar things that contain more atoms than a grain of sand

From the complexity of the human body to the microscopic realm of bacteria, and even to the contents of your kitchen, numerous entities in the known universe contain an astonishingly greater abundance of atoms than a single grain of sand. Here are some examples that are made from more or less atoms than the number of atoms contained in a single grain of sand.

  1. Sugar Crystal (Sucrose): A sugar crystal, such as a grain of table sugar (sucrose), can contain on the order of 10^23 (one sextillion) to 10^24 (one septillion) atoms. The exact number depends on the size of the crystal.
  2. Salt Crystal (Sodium Chloride): A salt crystal, while smaller than a grain of sand, can contain approximately 10^18 (one quintillion) to 10^21 (one sextillion) atoms, depending on its size.

Smaller things and their atomic comparison

  1. Single Molecule of DNA: A single molecule of DNA can contain on the order of 10^9 to 10^10 (billions of atoms), with the precise number depending on the length of the DNA strand.
  2. Pollen Grain: A pollen grain from a plant is smaller than a grain of sand and may contain roughly 10^5 (one hundred thousand) to 10^6 (one million) atoms, depending on its size and the specific plant species.
  3. Particle of Dust: Dust particles can vary widely in size, but even small particles can contain thousands to millions of atoms, or approximately 10^3 (one thousand) to 10^6 (one million) atoms.
Entity Number of Atoms (Approx.) Atomic Comparison to a Grain of Sand
Pollen Grain 10^5 to 10^6 (Hundred Thousand to Million) Fewer atoms
Particle of Dust 10^3 to 10^6 (Thousand to Million) Fewer atoms
Sugar Crystal (Sucrose) 10^23 to 10^24 (Septillion) More atoms
Salt Crystal (Sodium Chloride) 10^18 to 10^21 (Sextillion to Quintillion) More atoms
Single Molecule of DNA 10^9 to 10^10 (Billion) More atoms
Human Body Approximately 7 x 10^27 (Septillion) More atoms
Grain of Sand (0.1mm) Approximately 29.8 quadrillion atoms Reference

These examples illustrate the incredible diversity and scale of objects in the universe, with some containing vastly more or less atoms than others. As you can see, the objects size does not determine how many atoms it is made up of. The sheer number of atoms in everyday objects is a testament to the remarkable complexity of the world around us.

Are there more atoms in a grain of sand than stars in the universe?

No, there are not more atoms in a grain of sand than there are stars in the observable universe, and here's why:

Astronomers estimate that there are roughly 100 billion to 200 billion galaxies in the observable universe. Each galaxy, on average, contains hundreds of billions to trillions of stars.

To provide a rough estimate, let's take the lower end of that range and calculate from there:

  • 100 billion galaxies × 100 billion stars per galaxy = 10,000,000,000,000,000,000,000 (10^21) stars

So, based on these estimates, there might be 10 sextillion stars (that's 10 followed by 21 zeros or 10,000,000,000,000,000,000,000 stars) in the observable universe. Keep in mind that this is just an approximation, and the actual number could vary due to what we learn in the future about the distribution and actual sizes of galaxies in the universe.

In contrast, as we've calculated above, a grain of sand can contain an estimated 29.8 quadrillion atoms (or 29,800,000,000,000,000 atoms).

Based on these estimates:

  • There are 10^21 (10 sextillion stars in the observable universe)
  • There are 29.8 x 10^15 (29.8 quadrillion atoms in a grain of sand)
Entity Comparison in Numerical Terms Comparison by Sheer Number
Stars in the Universe 10^21 (10 sextillion stars) 10,000,000,000,000,000,000,000 stars in the universe
Atoms in a Grain of Sand 29.8 x 10^15 (29.8 quadrillion atoms) 29,800,000,000,000,000 atoms in a grain of sand
Results from Comparison The number of atoms in a grain of sand (29.8 x 10^15) is about 3.36 x 10^5 times smaller than the estimated number of stars in the universe (10^21). So, there are approximately 336,000 times more stars in the observable universe than there are atoms in a grain of sand.

Therefore, it can be said that there are more stars in the observable universe than atoms in a single grain of sand. The number of stars in the universe is mind bogglingly immense. However, at scale one could also say the same for a single grain of sand!

Are there more atoms in a grain of sand than grains of sand on earth?

No, there are not more atoms in a single grain of sand than there are grains of sand on Earth. Let's break down those numbers to understand why.

We know that the number of atoms in a grain of sand can vary.  But, if we take our estimated number of 29.8 quadrillion atoms in a grain of sand (29.8 x 10^15 atoms), it is still much smaller than the average estimated number of grains of sand on Earth, which is on the order of 7.5 x 10^18. This means roughly that there are 7.5 quintillion grains of sand on Earth.

To compare:

  • Number of atoms in a grain of sand: 29.8 x 10^15 or (29.8 quadrillion atoms per grain of sand)
  • Number of grains of sand on Earth: 7.5 x 10^18 or (7.5 quintillion grains of sand on Earth)
Entity Comparison in powers of 10 Comparison by Sheer Number
Number of atoms in a grain of sand 29.8 x 10^15 (29.8 quadrillion atoms in a grain of sand)  29,800,000,000,000,000 atoms per grain of sand
Number of grains of sand on Earth 7.5 x 10^18 (7.5 quintillion grains of sand on Earth) 7,500,000,000,000,000,000 grains of sand on Earth
Comparison Results The number of grains of sand on Earth is larger than the number of atoms in a grain of sand by approximately 2.52 x 10^3 times, which means there are about 2,520,000 times more grains of sand on Earth than there are atoms in a single grain of sand.

In other words, the number of grains of sand on Earth is significantly larger than the number of atoms contained within any individual grain of sand.

Understanding power of 10 size comparisons

To help you further comprehend these atomic comparisons, I've listed the following breakdown of sizes into relative terms represented successively by larger powers of 10, where each term is a thousand times larger than the one before it.

The following table represents each ascending numerical term along with its respective value in powers of 10.

Numerical Term Value (in Powers of 10)
Thousand 10^3
Million 10^6
Billion 10^9
Trillion 10^12
Quadrillion 10^15
Quintillion 10^18
Sextillion 10^21
Septillion 10^24
Octillion 10^27
Nonillion 10^30
Decillion 10^33
Undecillion 10^36
Duodecillion 10^39
Tredecillion 10^42
Quattuordecillion 10^45
Quindecillion 10^48
Sexdecillion 10^51
Septendecillion 10^54
Octodecillion 10^57
Novemdecillion 10^60
Vigintillion 10^63