Mole Day and Chemistry’s Counting Unit
A dozen eggs can fit in a carton, but a dozen atoms would be far too small to see. Chemists often work with vast numbers of atoms and molecules, so they need a counting unit much larger than a dozen. Their answer is the mole: an amount containing approximately 602 sextillion particles.
That number is written as 6.02 × 10²³, or 602,000,000,000,000,000,000,000. It is so important in chemistry that it inspired Mole Day, a classroom observance on October 23. The date and the customary celebration time, from 6:02 a.m. to 6:02 p.m., echo the digits in 6.02 × 10²³. Mole Day is a way to celebrate chemistry, not the anniversary of a discovery.
A bigger kind of dozen
A dozen always means twelve, whether someone is counting eggs, pencils, or stars. The word tells us how many objects there are, not what they are made of or how much they weigh. A mole works the same way, except its number is enormously larger.
- observance:
- An event or occasion marked for a special purpose.
- approximate:
- Close to the actual value, but not exact.
- contributions:
- Parts that combine to make a total.
- rearrange:
- To put parts in a different order or arrangement.
- ratio:
- A comparison of quantities showing their relationship.
- quantities:
- Amounts or numbers of things.
- complications:
- Factors that make a situation harder to predict or manage.
- measurable:
- Able to be determined using a measuring tool or method.
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Preview questions from this passageShowHide
- 1Why does the author compare a mole to a dozen at the beginning?
- 2How can one mole of helium atoms and one mole of water molecules have different masses?
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About this explanatory article passage for Middle School
“Mole Day and Chemistry’s Counting Unit” is a explanatory article reading passage about The mole in chemistry, written for Middle School. It takes about 6 minutes to read (840 words) and comes with an interactive quiz and a printable worksheet with comprehension questions and an answer key.