Monthly Archives: September 2014

Murray Gell-Mann — September 15 is Aleksandr Mikhaylovich Butlerov’s birthday. Butlerov was a Russian organic chemist who introduced the term “chemical structure” to modern chemistry. Butlerov’s chemical structure theory was first to look at the chemical structure. He believed a molecule’s nature is determined by the type and number of atoms and their […]

Today In Science History – September 15 – Aleksandr Mikhaylovich ... Recently updated !

This entry was posted on September 14, 2014 by Todd Helmenstine (updated on August 15, 2026)

Vernier Scale — September 14 is Charles François de Cisternay du Fay’s birthday. Du Fay was a French chemist who made early contributions to the study of electrical charge. Du Fay discovered there were two types of electric charge. He named these charges after the methods he used to separate them. Vitreous (Latin […]

Today In Science History – September 14 – Charles du ...

This entry was posted on September 13, 2014 by Todd Helmenstine (updated on June 21, 2021)

Robert Robinson — September 13 is Hans Christian Joachim Gram’s birthday. Gram was a Danish doctor and bacteriologist best known for inventing the Gram staining technique in microbiology. Gram staining is a technique used to identify bacteria into two different groups, Gram-positive and Gram-negative. First, a sample of bacteria affixed to a microscope […]

Today In Science History – September 13 – Hans Gram ...

This entry was posted on September 12, 2014 by Todd Helmenstine (updated on August 13, 2025)

Pressure is a measurement of force per unit area. There are many different units associated with pressure. The SI unit for pressure is the pascal (Pa). One pascal is equal to one newton per square meter (N/m2). One pascal is a very small amount of pressure, so the kilopascal (kPa) is […]

Pressure Conversions – Atm to kPa

This entry was posted on September 12, 2014 by Todd Helmenstine (updated on January 20, 2022)

Richard Anthony Proctor — September 12 was a busy day in Moon science history. On September 12, 1959, the Soviet Union launched the second of their Luna Moon probes. Luna 1 was supposed to be the first man made object to reach the Moon, but an error during launch caused the probe to miss […]

Today In Science History – September 12 – Moon Science ...

This entry was posted on September 12, 2014 by Todd Helmenstine (updated on November 5, 2025)

Old-barometers — Pressure is a measurement of force per unit area. Unfortunately, there are many different units associated with pressure. The SI unit for pressure is the pascal (Pa). One pascal is equal to one newton per square meter (N/m2). One pascal is a very small amount of pressure, so the kilopascal (kPa) […]

Pressure Conversions – mmHg to kPa Tutorial

This entry was posted on September 11, 2014 by Todd Helmenstine (updated on January 20, 2022)

The Element Song lists the chemical elements of the periodic table. Tom Lehrer set the names of the elements to the tune of “I Am The Very Model Of A Modern Major-General” from the Gilbert and Sullivan opera buffa “The Pirates of Penzance.” Learning the lyrics is a fun way […]

The Element Song Lyrics

This entry was posted on September 11, 2014 by Anne Helmenstine (updated on June 21, 2021)

Rudolf Jakob Camerarius — September 11 is Harvey Fletcher’s birthday. Fletcher was an American physicist responsible for many contributions to sound and speech technology. While working for Bell Telephone Laboratory, Fletcher centered his research into human speech and hearing. He built the first practical audiometer to measure hearing loss and the first electronic hearing […]

Today In Science History – September 11 – Harvey Fletcher

This entry was posted on September 11, 2014 by Todd Helmenstine (updated on June 21, 2021)

Density is the measurement of the amount of mass per unit volume. Density calculations are done using the formula: whereρ = densitym = massV = volume Example Problems:1. Calculate the density in g/mL of 30 mL of solution that weighs 120 grams.2. Calculate the density in g/mL of 0.4 L of solution […]

Density Calculations – Worked Example Problem

This entry was posted on September 10, 2014 by Todd Helmenstine (updated on May 2, 2021)