1. The 1680s
   The ​1790s
2. The 1870s
   The 1910s

Titanium has a strong ability to bond with other elements. Because of that, it was not individually isolated until 1910.

1. The 1710s
   The 1800s
2. The 1860s
   The 1980s

Indium is a soft metal known for its silvery color. A simple metal to work with, it can be easily shaped or textured.

1. The 1760s
   The 1790s
2. The 1880s
   The 1920s

Hydrogen is the most abundant element in the universe. In total, it makes up around 75% of all the mass in the universe.

1. The 1690s
   The 1770s
2. The 1850s
   The 1930s

Though francium wasn't discovered until 1939, the element was predicted much earlier. In the late 1800s, scientists began to theorize that another alkali metal was out there, and it turned out to be francium.

1. The 1740s
   The 1800s
2. The 1890s
   The 1980s

Helium is a sneaky element with no color, taste or odor. It is the second most common element found throughout the universe.

1. The 1780s
   The 1820s
2. The 1890s
   The 2000s

The Lawrence Berkley Labs in California published a paper in 1999 announcing that they found element 118, oganesson. However, they had to retract the paper after their experiment couldn't be repeated.

1. The 1760s
   The 1810s
2. The 1920s
   The 1980s

Lithium is not found in its natural form anywhere on earth because of its radioactivity level. Instead, the element can be found in other places such as mineral springs and seawater.

1. The 1890s
   The 1930s
2. The 1980s
   The 1920s

Neon is a popular element used for lighting. However, it's also a good element for freezing and is used in cryonics.

1. The 1800s
   The 1890s
2. The 1940s
   The 1990s

Sodium is a necessary element for the human diet. In human cells, sodium regulates the fluid balance throughout the body.

1. The 1690s
   The 1770s
2. The 1840s
   The 1960s

Chlorine was used as a chemical weapon during World War I. Chlorine was effective because it was both toxic and lighter than air. However, it was also easy to detect because of its smell.

1. The 1660s
   The 1750s
2. The 1890s
   The 1940s

Credit for the discovery of astatine has been given to scientists from the University of California Berkley. However, researchers in Germany discovered it separately during WWII, but the war kept them from getting the information out.

1. The 1840s
   The 1900s
2. The 1990s
   The 2010s

Since it's a relatively new discovery, there is little information about flerovium. For example, scientists have yet to determine its melting point or boiling point.

1. The 1750s
   The 1800s
2. The 1880s
   The 1960s

A highly reactive metal, potassium is one of the most commonly known alkali metals. With an atomic number of 19, potassium contains 19 protons.

1. The 1770s
   The 1810s
2. The 1900s
   The 1980s

78% of the air we breathe is made up of nitrogen. However, we don't notice the nitrogen because it's odorless, tasteless and colorless.

1. The 1770s
   The 1820s
2. The 1900s
   The 1980s

Controversy surrounded the naming of hassium after it was discovered because both Russians and Germans claimed to have discovered the element. The Germans ultimately received credit, and the element was officially named in 1997.

1. The 1800s
   The 1850s
2. The 1920s
   The 1980s

In its purest form, hafnium has a bright, silvery shine to it. Once it oxidizes, the element gains a rainbow color.

1. The 1700s
   The 1810s
2. The 1880s
   The 1930s

After WWII, it was discovered that germanium had semiconductor qualities. With this discovery, the usefulness and production of germanium increased significantly.

1. The 1770s
   The 1820s
2. The 1900s
   The 1950s

Bromine is an important element in animal biology. However, it can also be used as a deadly gas, which is what happened in WWI.

1. The 1770s
   The 1810s
2. The 1920s
   The 2000s

In its gas form, oxygen has no odor, taste or color. However, when it's turned into a liquid or a solid, oxygen becomes a pale blue.

1. The 1790s
   The 1830s
2. The 1890s
   The 1950s

As with all elements that have an atomic number higher than 92, californium is a transuranium element. It is also the heaviest element that can be weighed.

1. The 1710s
   The 1770s
2. The 1880s
   The 2000s

At the moment, nihonium is not believed to be an important element in the biology of organisms. One reason for this is the high radioactivity of the element.

1. The 1660s
   The 1740s
2. The 1800s
   The 1970s

Hennig Brand was the first person to officially discover a new element when he found phosphorus. Other elements were known at the time, but no one is credited with discovering them.

1. The 1750s
   The 1790s
2. The 1860s
   The 1940s

Stainless steal is widely used because of its resistance to corrosion. This resistance is due to the presence of chromium.

1. The 1720s
   The 1870s
2. The 1910s
   The 2010s

Protactinium is an extremely radioactive metal that is toxic to animals. Of its 13 isotopes, none of them are stable.

1. The 1690s
   The 1810s
2. The 1880s
   The 1920s

Iodine is commonly used to make various medicines. However, some people can develop an allergy to the element.

1. The 1760s
   The 1850s
2. The 1920s
   The 1990s

Copernicium is named after Nicklaus Copernicus. Copernicus is credited with placing the sun at the center of the universe instead of the earth.

1. The 1700s
   The 1810s
2. The 1940s
   The 1980s

Plutonium was discovered during the early years of WWII. However, since it could be used to make an atomic bomb, its discovery was kept secret until after the war.

1. The 1800s
   The 1870s
2. The 1940s
   The 1990s

Scientists had a difficult time naming niobium because of its close association with tantalum. It officially received its current name in 1949.

1. The 1770s
   The 1840s
2. The 1890s
   The 1970s

Around 90% of manganese is mined from manganese dioxide. Common in nature, it is important in the production of steel.

1. The 1700s
   The 1790s
2. The 1850s
   The 1930s

A transition metal, yttrium is one of the rarest elements on earth. As a pure element, it is never found in nature.

1. The 1770s
   The 1820s
2. The 1900s
   The 1950s

Extremely radioactive, einsteinium glows blue when in the dark. It was discovered from exploding a hydrogen bomb in 1952.

1. The 1690s
   The 1740s
2. The 1860s
   The 1970s

Because it's so toxic, thallium has been commonly used in poisons for rats and insects. However, it's also been used as a murder weapon.

1. The 1680s
   The 1780s
2. The 1870s
   The 1960s

Tungsten is a refractory metal, meaning it's highly resistant to heat and wear. Other refractory metals include niobium and tantalum.

1. The 1800s
   The 1880s
2. The 1950s
   The 1990s

Cerium is an important element for those in the film industry. It is popularly used for lighting such as carbon arc lighting and projector lights.

1. The 1790s
   The 1870s
2. The 1940s
   The 2000s

Americium can be found naturally in minerals containing uranium. The element can also be found in nuclear power plants from the neutron bombardment​ of plutonium.