On this page
No other group shows the change from nonmetal to metal quite as clearly as group 14. At the top is carbon, the element of life. Below it are silicon and germanium, the semiconductors of the digital age. At the bottom are tin and lead, soft metals humans have used for thousands of years. Below them sits the superheavy flerovium.
Four outer electrons
Every group 14 element has four electrons in its outer shell (ns² np²). Gaining or losing four electrons takes a lot of energy, so the lighter members prefer to share electrons, forming four covalent bonds. The heavier members increasingly behave as metals.
The group at a glance (from our element data)
| Element | Type | Melting point (°C) | Density (g/cm³) | Electronegativity |
|---|---|---|---|---|
| Carbon | Nonmetal | ~3,550 (sublimes at 1 atm) | 2.27 (graphite) | 2.55 |
| Silicon | Metalloid | 1,414 | 2.33 | 1.90 |
| Germanium | Metalloid | 938 | 5.32 | 2.01 |
| Tin | Metal | 232 | 7.29 | 1.96 |
| Lead | Metal | 327 | 11.34 | 2.33 |
Density rises steadily down the group, but melting points fall — carbon’s giant covalent network is extraordinarily strong, while tin and lead are held by weaker metallic bonding. (Lead’s electronegativity in some tables is higher than you’d expect for a metal; different scales and oxidation states give different values.)
Carbon: the element of life
Carbon’s ability to form four strong bonds — including bonds to other carbon atoms, making long chains and rings — gives it an almost limitless range of compounds. Millions of carbon compounds are known, far more than for all the other elements combined apart from hydrogen. That’s the subject of organic chemistry, and it’s why life is carbon-based.
Carbon also has striking allotropes (different forms of the same element): diamond, graphite, graphene, fullerenes like C₆₀ and carbon nanotubes. See the hardest element.
Silicon: the element of electronics
Silicon is the second most abundant element in the Earth’s crust, almost always bonded to oxygen as silica (SiO₂, quartz and sand) or silicates. Glass is made mostly from silica.
Pure silicon is a semiconductor. Adding tiny, controlled amounts of phosphorus or boron (“doping”) lets engineers make transistors — billions of them on a single chip. Silicon is also the main material of solar cells. Unlike carbon, silicon doesn’t form long chains of Si–Si bonds easily, and the Si–O bond is far stronger, which is why silicon’s natural chemistry is dominated by rocks rather than anything like biochemistry.
Germanium: the first transistor
Germanium was one of the elements Mendeleev predicted in 1871, as “eka-silicon”, before it was discovered in 1886 by Clemens Winkler in Germany. Its measured properties matched Mendeleev’s predictions remarkably closely — a triumph for the periodic table. See the history of the periodic table.
The first transistor, built at Bell Labs in 1947, used germanium. Silicon later replaced it for most uses, but germanium is still important in fibre optics, infrared optics and some high-speed electronics.
Tin and lead: the ancient metals
Tin was alloyed with copper to make bronze, starting the Bronze Age more than 5,000 years ago. Today it’s used in solder and to coat steel (“tin cans” are actually tin-plated steel). Tin has an odd property: below about 13 °C its familiar metallic form can slowly change into a brittle grey powder (“tin pest”).
Lead is dense, soft and easy to melt, and was used by the Romans for water pipes — the word “plumbing” comes from its Latin name, plumbum, which is also why its symbol is Pb. Lead is toxic, especially to children’s developing nervous systems, and has been removed from petrol, paint and plumbing in most countries. Its main use today is in lead-acid car batteries, and as shielding against X-rays and gamma rays.
The inert pair effect
Going down the group, the +2 oxidation state becomes more stable than +4. Carbon and silicon are almost always +4 (as in CO₂ and SiO₂). But lead is most stable as +2 (as in PbO and Pb²⁺ ions), and lead(IV) compounds are strong oxidizing agents. This is called the inert pair effect: in heavier elements, the two outer s electrons are held more tightly and are less willing to take part in bonding.
Quick answers
Which group 14 elements are metals? Tin and lead (and flerovium, predicted). Silicon and germanium are metalloids; carbon is a nonmetal.
Why is it called the carbon group? Groups are often named after their first element. It’s also called the tetrels, or group IV(A) in older systems.
Why is lead’s symbol Pb? From its Latin name, plumbum. See element symbols that don’t match their names.
Advertisement