Platinum is a dense, malleable, and corrosion-resistant noble metal used in catalysts, electronics, jewelry, and laboratory equipment.
The electron configuration of platinum is [Xe] 4f14 5d9 6s1. Although the expected configuration might be [Xe] 4f14 5d8 6s2, one 6s electron is promoted to the 5d orbital to achieve extra stability from a nearly filled d-subshell.
Platinum is called a noble metal because it is highly resistant to oxidation, corrosion, and chemical attack. It does not react with oxygen or water under normal conditions and remains stable even in strong acids, except aqua regia, which can dissolve it.
\(\mathrm{Pt(s) + 4\,HCl + HNO_3 \rightarrow H_2[PtCl_6] + 2\,H_2O + NO}\)
Platinum exhibits several oxidation states, most commonly +2 and +4. Examples include:
These compounds are widely used in catalysis and coordination chemistry.
Platinum has a wide range of applications:
Cisplatin (cis-[Pt(NH3)2Cl2]) is a platinum-based chemotherapy drug used to treat various cancers. It binds to DNA in cancer cells, causing cross-links that inhibit replication and trigger cell death (apoptosis).
\(\mathrm{[Pt(NH_3)_2Cl_2] + DNA \rightarrow [Pt(DNA)(NH_3)_2] + 2\,Cl^-}\)
Platinum serves as a catalyst in automobile catalytic converters because it promotes redox reactions that convert harmful gases into less toxic ones:
\(\mathrm{2\,CO + 2\,NO \xrightarrow{Pt} 2\,CO_2 + N_2}\)
It helps reduce emissions of carbon monoxide, hydrocarbons, and nitrogen oxides from vehicle exhaust.
Platinum occurs naturally as native platinum and in ores such as sperrylite (PtAs2) and cooperite (PtS). It is mainly extracted as a by-product of nickel and copper refining. Recovery involves several steps, including flotation, chemical dissolution, and precipitation.
Platinum is used in jewelry because it is highly lustrous, ductile, and tarnish-resistant. Unlike silver or gold, platinum retains its shine indefinitely and does not oxidize. Its density also gives jewelry a premium weight and durability.
Platinum is a silvery-white, dense, and malleable metal with a melting point of 1768 °C and a boiling point of 3825 °C. It is an excellent conductor of electricity and heat and has high resistance to wear and corrosion.
Metallic platinum is non-toxic and safe for use in jewelry and medical devices. However, some platinum compounds, especially those used in industrial and medical processes (like cisplatin), can be toxic and must be handled carefully under controlled conditions.
Platinum catalyzes the hydrogenation of alkenes, a key reaction in the production of margarine and other organic compounds:
\(\mathrm{RCH=CH_2 + H_2 \xrightarrow{Pt} RCH_2CH_3}\)
Here, platinum facilitates the addition of hydrogen across the carbon–carbon double bond.