It is a unique physical property of an object that shows how tightly matter is packed together that object
Solid materials, such as iron and platinum, have densely packed particles
In outer space, the densest object observed to date is a neutron star
They have densities ranging between 37×1017 to 59×1017 kilogram per meter cube, which is 26×1014 to 41×1014 times denser than our Sun To put this into perspective, one teaspoon of neutron star material would have a mass of about 65×1012, which is nearly 1,000 times the mass of the Great Pyramid of Giza
What is the densest material on the Earth, and why are they important?
This might be the first time you have heard about the element named molybdenum
For starters, it belongs to the group of transition metals with an atomic number of 42
It doesn’t occur naturally in a pure metallic form; it only exists in oxidation states in various minerals
Most molybdenum compounds have high melting points and low solubility in water
They are extensively used in alloys, electrodes, and catalysts
Molybdenum is commonly used in steel because it increases the strength, hardness, and toughness of the alloy
Almost all ultra-high-strength steels with a yield point of at least 300,000 psi consist of 025 to 8% molybdenum
And since molybdenum can withstand very high temperatures without softening or expanding, it is also used to manufacture airplane and missile parts, industrial motors, and electrical contacts
Silver is nearly half as dense as gold, which means one gram of silver would be almost double the size of one gram of gold in terms of volume
Although it is not as impressive as gold or platinum, it has many extraordinary properties
For instance, silver exhibits the highest thermal conductivity, electrical conductivity, and reflectivity compared to any metal
It is found in the Earth’s crust in a free elemental form or in minerals like chlorargyrite and argentite
From historical times, silver has been valued as one of the crucial minerals on Earth, which is still the case today
Not only has it been used to make currencies but also ornaments, tableware, and modern electronic products like solar panels
Since it has high thermal and electrical conductivity, it is extensively used in the electronics industry for developing conductors and coatings
Denser than most commonly used materials, lead has the highest atomic number of any stable substance
It is soft and malleable and has a relatively low melting point
On Earth, lead is one of the commonly found elements alongside sulfur
Lead’s high atomic weight and tightly-packed face-centered cubic structure give it a density of 1134 grams per centimeter cube, which is higher than common metals like copper, iron, and zinc
It is now a well-accepted fact that lead was known to humans, even before 6000 BCE, and was probably used for metal smelting
Ancient Egyptians were the first to use lead as a consumer product
In the 21st century, lead plays an important role in many industrial sectors (including construction works) due to its high density and extreme tolerance for corrosion
Named after the Thor, the Norse god of thunder, thorium is a moderately strong radioactive metal and its known isotopes are unstable
This naturally occurring radioactive metal is found in water, rock, and soil
It is about three times as abundant as uranium in the Earth’s crust
There might be more untapped energy available for use from thorium in the Earth’s crust than from combined uranium and fossil fuel sources
Most of the Earth’s internal heat has been attributed to thorium and uranium
As per the World Nuclear Association, India has the largest thorium reserve in the world, followed by Brazil, Australia, and the USA
While thorium is harder than other radioactive materials like plutonium and uranium, it is less dense than both
The most common impurity is thorium dioxide — even the purest samples contain approximately 01% of the dioxide
Today, thorium is used to improve the strength of magnesium, control the grain size of tungsten in electric lamps, coat tungsten wire in electrical instruments, and build heat-resistant ceramics
Moreover, numerous thorium reactors have been constructed to replace uranium in nuclear reactors
Discovered in the early 1800s by English chemist William Wollaston, Rhodium is known for its extreme corrosion resistance and chemically inert characteristics
It is one of the rarest substances in the Earth’s crust, containing 00002 parts per million
Although a large amount of rhodium is retrieved from platinum and other platinum group elements, at least one of its isotopes (103 Rh) is found naturally
Surprisingly, it has also been detected in some potatoes, with concentrations ranging from 08 to 30 parts per million
It has a lower density and a higher melting point compared to platinum
It is not affected by many acids (including nitric acid) but dissolves slightly in aqua regia
Today, it is mostly used as a catalyst in TWC or three-way catalytic converters (exhaust control systems) in petrol or diesel engines as they help minimize nitric oxide and nitrogen dioxide emissions
In nuclear reactors, rhodium detectors are used to determine the neutron flux level
It is also alloyed with palladium and platinum to improve hardness and corrosion resistance
Mercury is quite an interesting element in the periodic table
It is one of the two solid elements that becomes liquid under normal room temperature and pressure, the other being bromine
Its melting and boiling points are −388 °C and 3567 °C
Its density is about 135 times higher than water, so a small amount of mercury feels surprisingly heavy
And since it has a high surface tension, it forms almost spherical beads on glass
When it transforms from liquid to solid, it changes volume by nearly 4% (from 1369 g/cm3 to 14184 g/cm3)
Since mercury expands and contracts in a fixed manner with temperatures, it is used in manometers, barometers, thermometers, sphygmomanometers, float valves, and various other devices
However, its use in sphygmomanometers and thermometers has largely been phased out because of its toxic nature
Today, it is primarily used for electronic applications and manufacturing industrial chemicals
Gaseous mercury, for instance, is used in fluorescent lamps, mercury (II) chloride serves as a catalyst in the production of polyvinyl chloride (PVC), and solid mercury(II) sulfide is used as a pigment in rubber, plastic, and paints
Earlier known as tantalium, it belongs to the refractory group of metals, which constitutes a minor portion of different types of alloys
It’s dense, ductile, and highly conductive to electricity and heat
Solid tantalum has a body-centered cubic crystal structure with Young’s modulus of 186 GPa and yield stress of 331 MPa While the metal is very hard, it is known for its corrosion resistance property — even at temperatures lower than 150 °C, tantalum doesn’t react with aggressive aqua regia (a mixture of nitric acid and hydrochloric acid)
It makes up 1 or 2 parts per million of the Earth’s crust by weight
It is hard, rare, and highly corrosion-resistant, which makes it the perfect material for high-performance capacitors
Due to its impressive oxidation resistance and high melting point, it is used to build vacuum furnace parts, valve bodies, and thermowells
Like thorium, Uranium is weakly radioactive
It is naturally found in three isotopes: uranium-238, uranium-235, and less common uranium-234
While it occurs in low concentrations in rock, water, and soil, it is commercially extracted from uranium-bearing minerals like uraninite
The existence of such an element was first discovered in 1789; however, its radioactive properties were discovered only in 1896 by Eugène-Melchior Péligot, and its practical use was done for the first time in 1934 after the Manhattan Project
The metal is denser than lead and tantalum but slightly less dense than gold and tungsten
Due to its unique properties, it is widely used in high-density penetrators in the military sector
Depleted uranium (which is less radioactive) can be alloyed with other metals like molybdenum or titanium, so that it can be used as a shielding material to store and transport radioactive substances
Although depleted uranium is less radioactive, it is dense enough to halt radiations from strong sources like radium
And since it can be machined and cast with ease at a relatively low cost, it is preferred over similarly dense materials
Tungsten is obtained from rare minerals like scheelite and wolframite
It was first identified as an element in 1781 and classified as a metal in 1783
Tungsten has the highest melting point (except carbon), highest tensile strength, and highest boiling point of all known elements
While pure single-crystalline tungsten is ductile and can be cut with harder metal, polycrystalline tungsten is intrinsically brittle and hard to work
Its most common applications include X-ray tubes, incandescent light bulb filaments, welding electrodes, radiation shielding, and superalloys
A few tungsten compounds are used as catalysts to produce industrial chemicals
Recently, tungsten has become popular in the 3D printing industry
Its high thermal conductivity and wear resistance enhances the printing quality of abrasive filaments
Moreover, Metallic tungsten is utilized in jewelry as an alternative to platinum or gold
Since it is harder and causes fewer allergic reactions than gold alloys, it can be used to make rings, necklaces, and bangles with brushed finishes
At present, the largest producer of tungsten is China (66,000 metric tons every year), followed by Vietnam (4,500 metric tons) and Russia (2,400 metric tons)
Gold-Coated James Webb Space Telescope
Gold is one of the most precious, popular, and sought-after materials on Earth
As per various studies, gold originated from supernova nucleosynthesis and from the collision of neutron stars in distant space
On Earth, it is found in natural rocks formed billions of years ago
It mostly occurs as tiny (microscopic) particles embedded in rock, typically together with sulfide minerals or quartz
Earth’s oceans also contain very small amounts of gold — there are approximately ten grams of gold for every one billion metric tons of ocean water in the Atlantic and North Pacific
Since gold has high resistance and electrical conductivity, it is used to make electrical connectors for all types of computerized devices
Like all other metals, the density of gold decreases as it gets hotter
At just below its melting temperature (1064 °C), its density reduces to 1831 g/cm3
At just above this temperature, the density of molten gold reduces to 1719 g/cm3
Have you ever wondered why you always get impure gold whenever you buy jewelry?
Well, that’s because pure (24 carats) gold is soft
To make it more durable and strong, other metals like copper and silver are added, so it becomes impure in the process
When gold is alloyed with other metals, the overall density of the alloy is reduced
The 18-carat gold with an equal proportion of copper and silver has a density of 154 g/cm3, while 9-carat gold has a density of 11 g/cm3
According to Statista, the United States has approximately 3,000 metric tons of gold reserves in mines
Australia has the largest share of the world’s gold mine reserves
It accounts for 11,000 metric tons of gold, followed by Russia (6,800 metric tons)
Plutonium is the densest radioactive element on Earth
Plutonium has a total of seven allotropes, whose densities range between 16 to 186 g/cm3
Contrary to most of the elements in the periodic table, plutonium’s density increases when by 25% when it melts
The density of the molten plutonium, however, decreases with temperature
Near its melting point, it has a relatively high viscosity and surface tension than other metals
On a large scale, this deadly element was first used in the Manhattan Project — a substantial amount of plutonium was used to detonate a nuclear weapon (named “Fat Man”) in Nagasaki, Japan
After World War II, its use was solely restricted to producing commercial nuclear energy
Today, about 35% of the energy generated in nuclear power plants comes from plutonium
It is formed in nuclear power reactors from uranium-238 as a by-product
The isotope plutonium-238, in particular, emits a massive amount of thermal energy with low levels of neutron rays and gamma rays
One kilogram of plutonium-238 can produce nearly 570 watts of heat
Read: 15 Intriguing Facts About Uranium | A Weak Radioactive Metal
It has the highest boiling point, except for carbon and tungsten
It also has the highest boiling point and third-highest melting point of any stable element at 5596 °C
As of the densest elements on Earth, it has a hexagonal close-packed crystal structure
At normal temperature and pressure, it doesn’t react with nitric acid, hydrochloric acid, sulfuric acid, aqua regia, and alkalis
Rhenium doesn’t occur freely in nature
It is extracted from porphyry molybdenum deposits and other minerals, usually in very low concentrations averaging 0001 parts per million
Like other platinum group metals, rhenium is a precious Earth element, and its alloys are unique, with high melting points and impressive mechanical properties
Due to these unique properties, rhenium alloys are used in exhaust nozzles and turbine blades of jet engines
Moreover, molybdenum-rhenium and tungsten-rhenium alloys are utilized in heating elements, welding rods, semiconductors, metallic coatings, and X-ray anodes
Platinum is one of the rarest Earth metals, with an average abundance of 5 micrograms per kilogram
It is found in Earth’s crust as native deposits and in some copper and nickel ores
The element is also one of the least reactive metals that exhibits excellent corrosion resistance even at high temperatures
Since it doesn’t react with other materials under high temperatures and pressure, it is often found as native platinum
Although it remains unaffected by water and air, it dissolves in hot concentrated sulphuric and phosphoric acids and hot aqua regia
Despite being dense, pure platinum is soft and can be easily damaged (just like gold)
That’s why it is hardened by mixing with other metals like palladium, ruthenium, rhodium, and iridium
Platinum-ruthenium alloy, for example, has a bright luster and doesn’t tarnish
Besides jewelry, Platinum is used in vehicle emissions control devices, dentistry equipment, laboratory equipment, electrodes, catalytic converters, and turbine engines
About 80% of the total platinum is produced in South Africa
The country produces 130 metric tons every year
Russia comes in a distant second place, with an annual production capacity of 19 metric tons
Iridium is the second-densest element and one of the rarest elements in Earth’s crust
It was discovered in 1803 in residues of platinum ores by an English chemist Smithson Tennant
It has two naturally occurring, stable isotopes: Iridium-191 and Iridium-193
Iridium also has the most corrosion-resistant property of any metal, even at extreme temperatures near 2,000 °C
At normal temperature and pressure, it is not affected by bases, acids, or most strong chemicals
These properties make iridium a valuable transition metal
Since iridium is eight times stronger and six times harder than platinum, it is primarily used to make high-performance spark plugs
While copper spark plugs can last 20,000 miles, platinum electrodes have a life expectancy of about 100,000 miles, and iridium spark plugs can last 25% longer than that
It can also be used as electrodes for the production of chlorine (in the Chlor-alkali process) and as crucibles for the recrystallization of semiconductors at high temperatures
Moreover, the current display technology, specifically OLED screens, uses iridium compounds to produce light and vibrant colors
Osmium is the densest naturally occurring element on Earth
It is also among the rarest elements, making 50 parts per trillion of the Earth’s crust
This gray-white metal is twice as dense as lead
It is very hard, brittle, and has the fourth-highest melting point of all elements (after carbon, tungsten, and rhenium)
Its bulk modulus is extremely high, ranging from 395 to 462 GPa, which is comparable to that of diamond
These properties make osmium difficult to machine, form, or work, even at high temperatures
While pure osmium doesn’t occur in nature, its native alloys are found with platinum metals
He discovered the element together with iridium in the residues of platinum ores that are insoluble in aqua regia
Due to the extreme toxicity and volatility of osmium oxide, the element is rarely used in its pure form
It is usually alloyed with other platinum-group metals for high-wear applications
These alloys are used to make tips of fountain pens, electrical contacts, and instrument pivots
Read: 20 Rarest And Most Expensive Materials On Earth
Is diamond the hardest material found on Earth?
No Researchers have discovered six materials that are harder than diamonds
In proportion to thickness, graphene is the strongest material known to humans
Read: 10 Hardest Minerals In The World | On Mohs Scale
What’s the most expensive liquid in the world?
Onasemnogene abeparvovec is currently the most expensive medication available in liquid form
Read: 16 Most Expensive Liquids In The World