Elements

Helium

The only element without a solid state: it is liquid at absolute zero.

Potassium (from potash). Starts the fourth period.

Can be made to burn with a lavender-colored flame.

Vanadium (from Vanadis, another name for Freya).

Chromium (from Greek 'chroma' meaning 'colour').

Cobalt (from German 'kobald' meaning goblin, an accusation of miners astray in their search for tin).

Nickel (from German 'kupfernickel' meaning devil's copper or St. Nicholas copper). The discoverer analyzed a mineral which he thought might contain copper.

Gallium (from Gallia). Discovered by a French guy in 1875, see also 32 Ge.

Germanium (from Germania). Discovered by a German guy in 1886, see also 31 Ga.

Rubidium (meaning deepest red). Starts the fifth period.

Few uses. Due to chemical similarity to 19 K (potassium) we absorb it in food. Nontoxic. The average person stores about 500 mg.

Niobium (from Niobe, the daughter of King Tantalus). So named due to its similarity to 73 Ta (tantalum), which is below in the same group.

Technetium (from Greek meaning artificial).

Ruthenium (from Latin meaning Russia).

Rodium (from Greek meaning rose-colored).

Palladium (from the asteroid Pallas, named after Pallas the goddess of wisdom).

Silver (argentum).

It's used in mirrors because it's the best reflector of visible light known.

Silver tarnishes over time, forming a black oxide. Where appearance is important, as in jewelry, we use sterling silver, an alloy with mostly silver.

Indium (from Latin meaning indigo).

Tin.

Antimony (from Greek meaning 'not alone'). The symbol Sb is from the Latin name stibium. Found in nature as the mineral stibnite AKA antimonite.

A solid metalloid in the nitrogen group.

History: Used in Ancient Egypt as a mascara, in the Middle Ages to harden lead for type (printing press).

Uses: alloys (with lead particularly) in batteries, types, bullets; some electronic devices; some flame-retardant materials.

Toxic.

Cesium (caesius means sky blue and cesium flame is sky blue). Starts the sixth period.

An important use is the cesium clock, i.e. atomic clock, used in mobile phone networks and GPS.

Lanthanum, the first in the lanthanides (57-71).

Cerium (from the asteroid Ceres, named after Ceres the god of agriculture).

Lutetium (from Lutetia, the old name for Paris). Ends the lanthanides.

Hafnium (from the Latin name for Copenhagen, Hafnia).

Tungsten. The English name is derived from a Swedish word, but the Swedish name for 74 W is something else altogether (volfram).

Has the highest melting point of any element (3414 C).

Used to be in lightbulbs. Calcium and magnesium tungstenates are still used in fluorescent lighting. Tungsten carbide (tungsten + carbon) is immensely hard, very important to metalworking, and a great material for drills and saws.

Iridium (from Iris the goddess of the rainbow).

Almost as unreactive as gold. The most corrosion-resistant material known.

Discovered together with osmium (76 Os): When crude platinum (78 Pt) was dissolved in aqua regia, it left behind a black residue thought to be graphite, but Smithson Tennant found it to be two new elements, named iridium due to its colourful salts and the other osmium due to its curious odor.

Gold. The Latin name is aurum.

Not toxic; chemically unreactive, though it will dissolve in "aqua regia", a mixture of nitric and hydrochloric acid.

Mercury AKA quicksilver (hydrargyrum).

Mercury, and 35 Br, are the only liquid elements at room temperature.

Had many uses in the past, but is highly toxic. Now mostly used as catalyst.

Polonium, the first radioactive element (with the exception of 43 Tc), and all following elements are radioactive.

Francium. Starts the seventh period.

Has no uses. Half-life of 22 minutes.

Actinium, the first in the actinides (89-103).

Uranium (from Uranus).

Most uranium comes in the form of U-238, which is not fissile. Enriched uranium has a greater proportion of U-235, depleted uranium is back to being mostly U-238, with even less 235 than naturally occurring uranium.

Uranium weighs 19.1 g/cm³ which is almost as heavy as gold (19.3 g/cm³).

Plutonium

Californium, the last useful element. Einsteinium (99 Es) and above are only for research as of ~2015.

Used in metal detectors.

• Periodic table