Chemist Edward Frankland. Scientist Famous for Theory of Valence and Chemical Bond Formation.
Life and works of Sir Edward Frankland who laid the foundation for the theory of valence and discovered the science of organometallic compounds.
Sir Edward Frankland was a foremost English chemist of his day. He laid the foundation of modern structural chemistry through his theory of valence, a concept that atoms, when they come together to make chemical compounds, did so in regular ratios. He also introduced the term “bond” to describe the way that atoms link to each other.
Early Life of Edward Frankland in a Nutshell
Edward Frankland was born in Lancashire, England on January 18, 1825, an illegitimate son of a prominent lawyer. At 15-years-old, he became an apprentice in a chemist’s shop. In 1847, he was a chemistry teacher at Queenwood College, Hampshire, but soon went to Germany in Marburg to work with Robert Bunsen for three months.
Frankland Discovers the Science of Organometallic Compounds
While working with Bunsen, Frankland became fascinated by a class of chemicals that bound metal atoms with other compounds, now called organometals. The particular set of these that he was looking at were zinc dialkyls.
As well as an object of study, he used these compounds for entertainment. He described it that when he added water to these compounds, a greenish blue flame several feet long shot out of the tube, caused excitement among those present and it diffused an abominable odor.
Frankland’s pattern had actually been seen before. A few years earlier, Alexander Crum Brown reported it in his M.D. thesis at the University of Edinburgh, entitled “On the Theory of Chemical Combination.”
Findings on General Symmetry of Chemical Compounds Formula
What both Crum Brown and Frankland had seen was that when elements combine, they do so in whole number ratios. Antoine Lavoisier had been moving to the idea when he split and recombined water, and found constant proportions of hydrogen and oxygen were always involved. Farmland took this further and developed what he called atomicity, now known in the chemistry as valence. In his first report he said, “The combining power of the attracting element… is always satisfied by the same number of atoms…”
The Theory of Valence
The theory of valence is, with the valence number being the number of chemical bonds that any given atom can make with other atoms when forming a compound, in terms of atomic bonding, the idea is that every atom has a fixed number of bonds that it can form, and that to be stable, all of these bonds must be used.
For example, if a hydrogen atom bonds with another hydrogen atom, then the bonds on each atom will be fully used in forming H2, otherwise known as the molecule of hydrogen. Alternatively, two hydrogen atoms can combine with the two bonds of oxygen to form H-0-H, or water. Frankland further introduced the compound notation for what is now known as H20 (water.)
Valence of Carbon Forming Organic Chemical Compounds
The concept of valence was picked up and developed later by Friedrich August Kerkule, who decided that the valence of carbon must be four. He further suggested a radical idea that this would allow carbon to form into chains of atoms, therefore creating huge molecules. He was right.
In 1865, Kerkule proposed that carbon not only form chains but also link into closed six-atom rings. In the simplest carbon molecule, three of each carbon’s bond on each carbon binds to a hydrogen atom. The resulting molecule contains six atoms of carbon and six hydrogen atoms and is known as benzene, an organic chemical compound.
Legacy of Edward Frankland
Edward Frankland’s concept of the theory of valence forms the foundation of modern structural chemistry. Later followed by Kerkule’s realization that carbon can form chains and rings, gave rise to organic chemistry. Frankland and Kerkule enabled chemistry to become an important tool to create new complex compound molecules beyond what already exist in their day.
Frankland became professor of chemistry at the Royal College of Chemistry and he published Water Analysis for Sanitary Purposes.
Benzene’s structure in terms of the theory of valences produced a huge impact in chemical engineering. Its industrial use ranges from medical drugs to textile dyes.
In 1897, Frankland was knighted. He died two years later in August 9, 1899 after a brief illness.