Chemical Elements

What Is a Chemical Element?

An element is a chemical atom with rectified protons inside its nuclei. We cannot split it into more basic substances, as it is a pure chemical substance. The number of protons is an element’s defining characteristic, corresponding to its atomic number. All atoms of the same element have the same atomic number.

One hundred eighteen elements have been recognised by the IUPAC (International Union of Pure and Applied Chemistry). Of these, 24 are formed during nuclear reactions, whereas 94 occur naturally on earth. Lithium, sodium, and potassium are a few intrinsically forming elements on the earth’s crust. In contrast, elements like samarium, promethium, plutonium, and neptunium are formed during nuclear reactions.


Lithium is a chemical element with the symbol Li and atomic number 3 in the periodic table. It is moderately abundant and is present in the earth’s crust at 65 ppm (parts per million). Lithium is a silvery-white alkali metal.

Lithium should be stored in a vacuum or inert liquid, like purified kerosene or mineral oil, as it is a very reactive and flammable element. It imparts a metallic lustre that gets tarnished in the presence of moist air.

Physical Properties of Lithium

Name of ElementLithium
Chemical SymbolLi
Atomic Number3
Blocks block
Relative Atomic Mass6.94 g mol-1
Appearance at 20 °CSolid
Boiling Point1615 K, 1342°C, 2448°F
Melting Point453.65 K, 180.50 °C, 356.90 °F
Density0.534 g cm−3
Discovered byJohan August Arfvedson in 1817

Chemical Properties of Lithium

Name of ElementLithium
Electron Configuration[He] 2s1
 Stable Isotopes3Li6 and 3Li7
Oxidation State+ 1
Specific Heat Capacity3582 J kg−1 K−1


Samarium is a chemical element with the symbol Sm and atomic number 62 in the periodic table. It is a relatively hard silver-coloured metal that gradually oxidises in the air and ignites spontaneously at 150 oC. Chemically, samarium is a lanthanide. It shows one stable oxidation state of +3.

Samarium and its compounds act as catalysts and chemical reagents. It helps in the decomposition of plastics, dechlorination of pollutants like PCB polychlorinated biphenyls, and dehydrogenation and dehydration of ethanol. It is also an anticarcinogen used to treat prostate cancer, lung cancer, osteosarcoma and breast cancer.

Naturally occurring samarium has five stable isotopes, 62Sm144, 62Sm149, 62Sm150, 62Sm152 and 62Sm154, and two exceptionally long-lived radioisotopes, 62Sm147 and 62Sm148, with 62Sm152 being the most plentiful, i.e. 26.75%. It is a beta emitter with a half-life of 46.3 hours.

Physical Properties of Samarium

Name of ElementSamarium
Chemical SymbolSm
Blockf block
Boiling Point2067 K, 1794°C, 3261°F
Melting Point1345 K, 1072°C, 1962°F
Density7.52 g cm−3
Appearance at 20 °CSolid
Relative Atomic Mass150.36 g mol-1
Atomic Number62
Discovered byPaul Emile Lecoq de Boisbaudran in 1879

Chemical Properties of Samarium

Name of ElementSamarium
Electron Configuration[Xe], 4f6, 6s2
Total Number of IsotopesSeven
 Stable Isotopes62Sm144, 62Sm149, 62Sm150, 62Sm152 and 62Sm154
Oxidation State+ 3