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January 20 th marks the passing of Carl Gräbe. Gräbe was a German organic chemist who discovered a method to synthesize the distinctive red alizarin dye with Carl Liebermann. This discovery greatly reduced the cost of the red dye that was previously only available from the madder plant. Gräbe was also the chemist who introduced the nomenclature used to describe bond locations on benzene rings. Benzene is a ring of carbon atoms forming a hexagon. When two functional groups attach themselves to different points of the hexagon, different prefixes are used to differentiate different patterns. Gräbe introduced the use of the prefixes para-, meta-, and ortho- to the organic chemist's dictionary. The para- prefix indicates the functional groups are attached on opposite carbon atoms. Meta- is used to indicate when there is a one carbon atom gap between functional groups. Ortho- is used when two functional groups are on adjacent carbon atoms.

Definition of a Molecule Molecules are formed when two or more atoms are held together by chemical bonds. Molecules Formed by Covalent Bonds For example, the oxygen molecule consists of two atoms of oxygen. In the case of oxygen, the bond that holds the two atoms together is known as a covalent bond, and here is how it works. The oxygen atom has 8 each of protons, neutrons, and electrons. The protons and neutrons are found in the center of the atom, known as the nucleus, and the electrons surround the nucleus in layers, or shells. The oxygen atom has 2 electrons in its first shell, and 6 in its second and outer shell. However, in chemistry, there exists the octet rule, which states that atoms generally strive to have 8 electrons in their outer shell. The oxygen therefore is 2 electrons away from a complete outer shell. When it binds with another oxygen atom, they can share two pairs of electrons and so each will have 8. When atoms share electrons like that, they for...

What Are Types of Chemical Reactions

Chemical & Physical Properties Beryllium Atomic Number: 4 Symbol: Be Atomic Weight: 9.012182(3) Reference: IUPAC 2009 Discovery: 1798, Louis-Nicholas Vauquelin (France) Electron Configuration: [He]2s 2 Other Names: Glucinium or Glucinum Word Origin: Greek: beryllos , beryl; Greek: glykys , sweet (note that beryllium is toxic) Properties: Beryllium has a melting point of 1287+/-5°C, boiling point of 2970°C, specific gravity of 1.848 (20°C), and valence of 2. The metal is steel-gray in color, very light, with one of the highest melting points of the light metals. Its modulus of elasticity is a third higher than that of steel. Beryllium has high thermal conductivity, is nonmagnetic, and resists attack by concentrated nitric acid. Beryllium resists oxidation in air at ordinary temperatures. The metal has a high permeability to x-radiation. When bombarded by alpha particles, it yields neutrons in the ratio of approximately 30 million ne...

Chemical & Physical Properties of Calcium   Calcium Calcium Basic Facts: Symbol: Ca Atomic Number: 20 Atomic Weight: 40.078 Classification: Alkaline Earth CAS Number: 7440-701-2 Calcium Periodic Table Location Group: 2 Period: 4 Block: s Calcium Electron Configuration Short Form : [Ar]4s 2 Long Form : 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2   Shell Structure: 2 8 8 2 Calcium Discovery Discovery Date: 1808 Discoverer: Sir Humphrey Davy [England] Name: Calcium derives its name from the Latin ' calcis ' which was the word for lime (calcium oxide, CaO) and limestone (calcium carbonate, CaCO 3 ) History: The Romans prepared lime in the first century, but the metal was not discovered until 1808. Swedish chemist Berzelius and Swedish court physician Pontin created an amalgam of calcium and mercury by electrolyzing lime and mercury oxide. Davy managed to isolate pure calcium metal from their amalgam.

Chemical & Physical Properties Magnesium Atomic Number: 12 Symbol: Mg Atomic Weight: 24.305 Discovery: Recognized as an element by Black 1775; Isolated by Sir Humphrey Davy 1808 (England) Electron Configuration: [Ne] 3s 2 Word Origin: Magnesia , a district in Thessaly, Greece Properties: Magnesium has a melting point of 648.8°C, boiling point of 1090°C, specific gravity of 1.738 (20°C), and valence of 2. Magnesium metal is light (one-third lighter than aluminum), silvery-white, and relatively tough. The metal tarnishes slightly in air. Finely divided magnesium ignites upon heating in air, burning with a bright white flame.

The scientific method is an objective way to explore the world around us. It is a systematic means of asking and answering questions, used by both scientists and non-scientists, all over the world. By the end of this quiz, you should feel confident you know the order of the steps of the scientific method and the difference between the three types of variables you may encounter in an experiment... Take the quiz

Have you ever wanted to complete a word search containing the elements? Now you can fulfill that wish with the Element Word Search.