National Chemistry Week runs October 17–23, 2027, a yearly campaign to show how chemistry shapes daily life. The American Chemical Society started it more than three decades ago, and its local sections still lead hands-on events for kids and families.
Third Week of October
Every October, during the third week, from Sunday through Saturday. The 2023 edition covered October 15 to 21, and October 18 kicked off the 2026 week.
It usually overlaps with Mole Day on October 23.
ACS organizes it through its local sections. Businesses and schools often sign on as partners.
An ACS Tradition
A 2023 Senate resolution called that year’s event the 34th annual National Chemistry Week. It commended ACS and its partners for the events.
Older roots run underneath. On April 6, 1876, 35 chemists met at the College of Pharmacy of the City of New York to found it.
Congress incorporated ACS by an act that took effect on January 1, 1938, a 2026 Senate resolution notes.
The year 2026 was a milestone, marking the society’s 150th anniversary and the 135th of its New York Section.
New York shows how deep the roots go. That section and the New York Hall of Science have partnered on the week for decades, reaching more than 25,000 children.
Why Chemistry Gets a Week
Kids are the main audience. The campaign aims to reach the public, especially students from kindergarten through 12th grade, Colorado State University notes.
Themes tie chemistry to real life. In 2023, “The Healing Power of Chemistry” looked at medicines and vaccines.
Construction took over in 2026. “Chemistry Under Construction” explored the chemistry behind building, creating and transforming the world.
Volunteers make it work. ACS local sections, student groups and technical divisions all take part.
Universities join in too. In 2023, Colorado State’s chemistry department used the week to promote its undergraduate research labs.
PepsiCo has sponsored the New York celebration for over 20 years, QNS reported.
Ways to Take Part
Museums and colleges often host free demos. At New York’s Hall of Science, the 2026 event ran from 11 a.m. to 4 p.m. on Sunday.
- Try a safe kitchen experiment, such as making a pH indicator from red cabbage.
- Find a local ACS section event near you.
- Visit a science museum’s chemistry demo.
- Thank a chemistry teacher who made the subject click.
- Celebrate Mole Day with a math-and-science snack.
Frequently Asked Questions
What is Mole Day?
It’s a chemistry celebration named for a key unit of measure.
Who runs National Chemistry Week?
A national scientific society for chemists.
Is it only for scientists?
No. Most events are aimed at kids and families.
When is National Chemistry Week held?
During October’s third week, and the dates shift slightly from year to year.