Every science classroom you have entered will most likely have had a periodic table somewhere. It is a Bible for chemists and it can tell us a lot about the fundamental elements that make us what we are.
I could not go a week by without looking at a periodic table (basically all my chemistry homeworks require it).
Chemical elements are the simplest substances found in nature consisting of individual atoms.
Each nucleus of the atoms is surrounded by a cloud of negative electrons counteracted by a positive nucleus consisting of neutrons and protons making the overall charge of an atom neutral.
Within the periodic table you get the simplest, smallest and most fundamental elements such as hydrogen and helium down to very dense elements such as radium with atomic number 92. A lot of the heavier elements are unstable and often undergo radioactive decay.
The iron in our blood down to the oxygen we breath was fused in the very dense and extreme cores of large stars. The heavier elements after iron were created by supernova explosions which could reach such temperatures. However not all elements are “naturally” occurring.
Neptunium, einsteinium and nobelium are some of the man-made elements. Any element with an atomic number greater than 92 is considered to be a man-made element
As of February 2015, there are 26 man-made elements listed on the periodic table. The actinide series includes neptunium, polonium, americium, curium and berkelium. Californium, einsteinium, fermium, mendelevium, nobelium and lawrencium are also found in the actinide series. Elements 104 through 118 are located in period 7 of the periodic table. Man-made elements in period 7 include rutherfordium, ununtrium, flerovium and ununoctium.
Scientists have determined that some of them are produced naturally in very small quantities. All of the man-made elements are radioactive and have the ability to undergo nuclear fission. Scientists use nuclear reactors and particle accelerators to produce these elements.
Many of the man-made elements are named after scientists or historical figures. Curium, first identified in 1944, was named after Marie and Pierre Curie. Rutherfordium was named after Ernest Rutherford, the father of nuclear physics. Researchers identified rutherfordium by bombarding plutonium with neon ions. Einsteinium gets its name from theoretical physicist Albert Einstein. Researchers from Berkeley identified einsteinium in the debris created by a thermonuclear explosion.
The inert gases (noble gases) or group 0 atoms don’t react easily as they already have an ideal electron configuration which enables them to have a stable life.
The table is primarily split between groups and periods.
Down a group:
- Atomic radius increases
- Nuclear charge increases
- Electron repulsion and shielding increases
Across a period the electronegativity of atoms increases.
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.
The most important event in the history of the periodic table occurred in 1869 when the table was published by Dmitri Mendeleev , a Russian chemist , who built upon earlier discoveries by scientists such as Antoine-Laurent de Lavoisier and John Newlands.
This was a tiny insight into one of the best structures in modern science.
Happy belated national periodic table day ! (7th February)
Image credits to Google.
All writing is my own from school notes.