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Elements

There are about 90 natural elements found on Earth, and across the Universe.

Most are silvery-grey metals or colourless gases. They may look rather similar but each has unique properties. Compounds that the elements form with each other produce the astonishing variety of materials and colours all around us. They are what make us too.

Explore the Elements gallery at the Ulster Museum to find out more about these building blocks of the Universe.

Contact the author: Dr Mike Simms, Curator of Palaeontology

The Periodic Table © Dr Mike Simms

Elements of the Universe

Silicon carbide is a simple compound of silicon and carbon. It is used as a synthetic abrasive but it is also found as microscopic grains in some meteorites.

Silicon carbide grains were created in giant red stars and scattered into Space by stellar winds. These grains were swept up and incorporated into the planets as our Solar System formed from a cloud of dust.

Meteorites represent debris from the beginning of the Solar System, around 4567 million years ago, but the silicon carbide grains within them are even older still.

Synthetic silicon carbide. The block is about 30 cm long. © National Museums NI

Elements of the Earth

Many minerals are named after the place where they were first found. Some elements are too.

Strontium was first isolated in 1790 from the mineral strontianite, strontium carbonate. Both the mineral and the element take their name from the Scottish village of Strontian, where the mineral was first found.

The element was discovered by Adair Crawford and William Cruikshank. They were chemistry professors at the Royal Military Academy in Woolwich, but Adair was originally from near Belfast.

Strontianite from Strontian. Specimen is about 5 cm across © National Museums NI

Elements of Life

Living things are made largely from common elements, such as carbon, hydrogen, oxygen, nitrogen and phosphorus. Some other very common elements are hardly found at all.

Aluminium seems not to be used by any plants or animals. Silicon, one of the most abundant rock-forming elements, is found in just a few. ‘Glass sponges’ make their skeletons from silica (silicon dioxide), but most others are microscopic organisms.

Glass sponge, dredged from a depth of about 1000m off the west coast of Ireland. Specimen is about 30 cm high. © National Museums NI

Elements of Death

Hazardous substances have long been used to enhance beauty.

In the 1700s it was fashionable for the aristocracy to whiten their faces using ceruse. This is a powdered form of the white lead mineral cerussite (lead carbonate).

Lead is damaging to nerves, kidneys, skin and many other organs. Applying white lead to the face often caused ulcers, which needed more ceruse to cover them.

The most famous ‘victim of cosmetics’ was Maria Gunning, Countess of Coventry. She died from lead poisoning aged just 27.

The lead carbonate mineral cerussite, from Tynagh Mine, Co. Galway, Ireland. Specimen is about 10 cm high © National Museums NI

Elements of Progress

Copper was the first metal to be smelted from mineral ores more than 5000 years ago.

This led to a revolution in tool and weapon-making, the Bronze Age, that lasted for 2000 years, until the start of the Iron Age.

Copper became important again around 500 years ago as a key ingredient, along with zinc, in brass.

Copper’s electrical conductivity is second only to silver. In the last 200 years copper has become increasingly vital for telecommunications and electric power transmission.

11,000V power cable from the 1950s, when large parts of rural Ireland were electrified for the first time. Cable is about 5 cm across. Donated by NIE © National Museums NI

Elements of Technology

Some elements are catalysts: they help chemical reactions without being used up themselves.

Platinum, palladium and rhodium are among the rarest of elements. More than half of the total amount of these metals mined each year is used in catalytic convertors for motor vehicle exhausts. They transform toxic gases into non-toxic ones.

Each catalytic converter contains just two grams of these rare elements. This is spread across more than 200 square metres of corrugated iron-chromium-aluminium alloy foil.

Walker catalytic convertor from a Jaguar car, 1993. The corrugated foil is visible inside the chromium-plated barrel. Barrel is about 15 cm across © National Museums NI

Elements of Colour

Cubic zirconia is a synthetic gemstone made from zirconium oxide. A small amount of yttrium is added to ensure that it forms stable cubic crystals, like diamond. This produces a brilliantly sparkling, but colourless, gemstone.

Tiny amounts of other element oxides – such as chromium, neodymium, holmium or erbium - are added to produce different colours.

Elements of Light

Electronic flashbulbs produce a brilliant burst of light - but only once. The electric current ignites a fine zirconium metal wire inside the bulb.

The best quality flashbulbs have contacts made of rhenium. This metal has one of the highest melting points of any element, to withstand the very high electric current needed to fire the bulbs.

Elements of Wealth

Gold and silver were the metals of choice for the first coins, more than 2500 years ago. These elements continued to be used for many coins until about 200 years ago.

Since then cheaper metals and alloys have been increasingly used, such as copper, zinc, nickel and even steel. Aluminium is used too because it is so cheap, but this was not always the case. Until 1886 aluminium was so difficult to produce that it was more valuable even than gold!

Elements of Fashion

Gold is rare and expensive. Only the wealthy can afford it.

Brass is cheap and, some might say, vulgar when used in fashion items. But metallurgists can produce particular alloys of brass that look a lot like gold.

Prince’s Metal is named after Prince Rupert of the Rhine. It is a yellow-coloured alloy of 75% copper and 25% zinc. Pinchbeck Brass, with about 90% copper and 10% zinc looks even more like gold.

Elements of Fission

Radium, mixed with zinc sulfide, was painted onto clock and watch faces throughout the first half of the 20th Century. These luminous dials were visible in the dark.

Radiation emitted by the radium causes the zinc sulfide to glow. Radium itself has a half-life of more than 1600 years but the dials stop glowing after just a few decades. This is because the same radiation damages the crystal structure of the zinc sulfide.

Radium alarm clock from the 1920s. The zinc sulfide has long since ceased to glow. Clock is about 18cm high © National Museums NI