1. Americium
   Uranium
2. Hydrogen
   Thorium

Hydrogen is an element which is represented by the symbol H and the atomic number 1. It is the lightest element and the most abundant in the universe. While it has many uses, it is particularly known for being used as a coolant in generators and as an energy resource in power plants.

1. Radon
   Krypton
2. Bismuth
   Mercury

Krypton is an element which is represented by the symbol Kr and the atomic number 36. It is used in lighting when taking photos, in magnetic resonance imaging and computer tomography as well as an insulating gas between window panes.

1. Thallium
   Gold
2. Lead
   Helium

Helium is an element which is represented by as the symbol He and the atomic number 2. It is a naturally occurring colorless and odorless gas which has quite a number of uses. It is however, mostly known for being used as a lifting gas in airships and balloons.

1. Zirconium
   Platinum
2. Iridium
   Erbium

Zirconium is an element which is represented by the symbol Zr and the atomic number 40. While it has no biological role, it is used in positron emission tomography cameras, jet engines and has also been shown to have benefits for patients with chronic kidney disease.

1. Carbon
   Barium
2. Xenon
   Iodine

Carbon is an element which is represented by the symbol C and the atomic number 6. It is one of the most abundant elements found in the Earth’s crust and is used by every living system as well as in lubricants, pigments, in electrodes and in charcoal.

1. Tin
   Palladium
2. Silver
   Technetium

Silver is an element which is represented by the symbol Ag and the atomic number 47. It is known for exhibiting high electrical and thermal conductivity. Most silver is produced as a byproduct of gold, lead and copper and the precious metal has been used in the creation of solar panels, utensils and money.

1. Niobium
   Oxygen
2. Rubidium
   Bromine

Oxygen is an element which is represented by the symbol O and the atomic number 8. It is one of the most abundant and combustible elements in the universe and is used in cellular respiration and photosynthesis in different organisms as well as in the creation of various compounds.

1. Arsenic
   Selenium
2. Zinc
   Iodine

Iodine is an element which is represented by s the symbol I and the atomic number 53. It is the heaviest stable halogen and has a number of uses including as a catalyst, dye and colorant, pharmaceutical, sanitation and photography. It is also required by the body in order to synthesize thyroid hormones.

1. Neon
   Gallium
2. Astatine
   Polonium

Neon is an element which is represented by the symbol Ne and the atomic number 10. It is a very expensive colorless and odorless noble gas which has been used in signs for its bright color as well as in vacuum tubes, wave meter tubes, helium lasers and also as a cryogenic refrigerant.

1. Zinc
   Francium
2. Barium
   Copper

Barium is an element which is represented by the symbol Ba and the atomic number 56. It has a very high chemical reactivity and as such is not found in nature. In its soluble ion form, it is poisonous and has been used in rodenticides. It is also used in barium sulfate was well as X-ray imaging.

1. Nickel
   Sodium
2. Cobalt
   Iron

Sodium is an element which is represented by the symbol Na and the atomic number 11. It is one of the most abundant elements found in the Earth’s crust and has many different uses across several fields. In living creatures, it is the major cation found in extracellular fluid and it also plays a role in nerve impulses.

1. Manganese
   Boron
2. Chromium
   Iridium

Iridium is an element which is represented by the symbol Ir and the atomic number 77. It is one of the rarest elements on earth, with only three tons being produced and consumed every year. It has been used to create spark plugs, and airplane parts as well as in medical imaging.

1. Potassium
   Silicon
2. Chlorine
   Sulfur

Silicon is an element which is represented by the symbol Si and the atomic number 14. It has an extremely high melting boiling points and can be found in substantial amounts in the Earth’s crust.

1. Aluminum
   Platinum
2. Magnesium
   Neon

Platinum is an element which is represented by the symbol Pt and the atomic number 78. It is one of the rarer and least reactive metals and has been used to create parts for vehicles as well as in hard disks, turbine engines and jewelry and anticancer drugs.

1. Fluorine
   Oxygen
2. Aluminum
   Nitrogen

Aluminum is an element which is represented by the symbol Al and the atomic number 13. Aluminum is known for having a low density as well as being able to resist corrosion. Because of this, it has been used in the transportation, aerospace, construction and packaging industries.

1. Carbon
   Boron
2. Hydrogen
   Sulfur

Sulfur is an element which is represented by the symbol S and the atomic number 16. It is one of the most abundant elements on the planet and has a wide variety of uses including in insecticides, furniture, as well as the treatment of acne. In the body, it is used as a cofactor and it is present in 3 amino acids.

1. Hydrogen
   Phosphorus
2. Helium
   Holmium

Phosphorus is an element which is represented by the symbol P and the atomic number 15. It is an essential element to life as it is a component of DNA, RNA, ATP and phospholipids. It is also found in different detergents, fertilizers and pesticides

1. Gold
   Copernicium
2. Californium
   Curium

Gold is an element which is represented by the symbol Au and the atomic number 79. It is one of the precious metals, and throughout history has been used in creating coins, jewelry, electronics, medicine and even in various food preparations.

1. Lithium
   Zinc
2. Potassium
   Calcium

Zinc is an element which is represented by the symbol Zn and the atomic number 30. In the body, it is an essential element and is needed for pre and postnatal development and in other areas, it is used as an anti-corrosive agent, in paints and in galvanization.

1. Sulfur
   Scandium
2. Silver
   Chlorine

Chlorine is an element which is represented by the symbol Cl and the atomic number 17. Chlorine has been used significantly in creating sanitation products like commercial bleaches as well as reagents, disinfectants and also in the production of polyvinyl chloride and plastics.

1. Indium
   Ruthenium
2. Mercury
   Palladium

Mercury, also known as quicksilver, is an element which is represented by the symbol Hg and the atomic number 80. It has quite a number of uses, some of which include thermometers, sphygmomanometers and fluorescent lamps, but it is also poisonous if considerable amounts are ingested or inhaled.

1. Calcium
   Praseodymium
2. Neodymium
   Dysprosium

Calcium is an element which is represented by the symbol Ca and the atomic number 20. It is the fifth most abundant element is the human body and plays a vital role in physiological and biochemical processes including signal transduction, muscle contraction and bone formation.

1. Mercury
   Lead
2. Uranium
   Plutonium

Lead is an element which is represented by the symbol Pb and the atomic number 82. Lead has quite a number of uses, some of which includes the production of bullets, weights, batteries and paints, as well as in construction and plumbing. It is also a neurotoxin and if it accumulates, it can cause blood disorders and damage the nervous system.

1. Actinium
   Arsenic
2. Antimony
   Titanium

Titanium is an element which is represented by the symbol Ti and the atomic number 22. Because of its low density and its immense strength, it is used in the aerospace industry to create engines, missiles and spacecraft. It is also used to make prosthetics, dental implants and mobile phones.

1. Germanium
   Moscovium
2. Radon
   Americium

Radon is an element which is represented by the symbol Rn and the atomic number 86. The gas has been listed as a carcinogen and as such, has been linked to lung cancer and increased risk of leukemia. Despite that, it has been used to treat some types of cancers.

1. Mendelevium
   Lawrencium
2. Iron
   Einsteinium

Iron is an element which is represented by the symbol Fe and the atomic number 26. It has been listed as the most common element on Earth and has been used since ancient times in manufacturing steel and concrete. In humans it is a component of hemoglobin and myoglobin, as well as being important in cellular respiration.

1. Protactinium
   Uranium
2. Plutonium
   Platinum

Uranium is an element which is represented by the symbol U and the atomic number 92. It has one of the highest atomic weights of all of the elements and can also be toxic to humans. It has been used in nuclear power plants and nuclear weapons and in early photography.

1. Cobalt
   Beryllium
2. Helium
   Lithium

Cobalt is an element which is represented by the symbol Co and the atomic number 27. It has been used as a blue pigment since ancient times in jewelry and paint and is still being used as one today. In the body, it is a component of a coenzyme called cobalamin or Vitamin B12.

1. Manganese
   Oxygen
2. Nitrogen
   Tin

Tin is an element which is represented by the symbol Sn and the atomic number 50. Because of how malleable it is, it has been used to produce corrosion resistant tin-plated steel, tin cans used for food and drinks, solder and PVC plastic.

1. Iron
   Cobalt
2. Bismuth
   Nickel

Bismuth is an element which is represented by the symbol Bi and the atomic number 83. When it is stable, it has one of the highest atomic masses and is used as an ingredient in pharmaceuticals in products like Pepto-Bismol, in cosmetics like eyeshadows and hairspray and also as a pigment.

1. Cadmium
   Plutonium
2. Tellurium
   Rhodium

Plutonium is an element which is represented by the symbol Pu and the atomic number 94. Some types of plutonium are able to sustain nuclear chain reactions and therefore are used in nuclear weapons and nuclear reactions. There are also some forms of plutonium that are used to power spacecraft and as heat sources.

1. Barium
   Cerium
2. Europium
   Copper

Copper is an element which is represented by the symbol Cu and the atomic number 29. It is one of the most popularly used elements in the word and can be found in everything from heat and electricity conductors in building materials to coins, jewelry and various pesticides.

1. Livermorium
   Nitrogen
2. Roentgenium
   Darmstadtium

Nitrogen is an element which is represented by the symbol N and the atomic number 7. This element forms almost 80% of the Earth’s atmosphere and can be found in all organisms as part of DNA and RNA and in the energy molecule; adenosine triphosphate.

1. Arsenic
   Hassium
2. Seaborgium
   Dubnium

Arsenic is an element which is represented by the symbol As and the atomic number 33. This element is used primarily in different types of ammunition, car batteries and pesticides. It is also very poisonous and can result in symptoms as mild as vomiting and abdominal pain to as serious as encephalopathy.

1. Fermium
   Francium
2. Flerovium
   Potassium

Potassium is an element which is represented by the symbol K and the atomic number 19. It is one of the elements that is essential for life as it plays a role in gastrointestinal motility, hormone secretion, glucose and insulin metabolism as well as homeostasis.

1. Polonium
   Promethium
2. Praseodymium
   Einsteinium

Einsteinium is a synthetic element which is represented by the symbol Es and the atomic number 99. Named after Albert Einstein, the element was discovered as a component of the first hydrogen bomb explosion, which occurred in 1952.

1. Molybdenum
   Manganese
2. Chromium
   Magnesium

Chromium is an element which has the symbol Cr and the atomic number 24. It is known for being resistant to corrosion as well as being extremely hard and is therefore used as components of structural material as well as engines and turbines. It is also used as a pigment and wood preservative.

1. Silicon
   Xenon
2. Sodium
   Calcium

Xenon is an element which is represented by the symbol Xe and the atomic number 54. The colorless and odorless gas has been used in the creation of flash lamps, lasers, general anesthesia, and some athletes have been known use it as a doping agent as it can increase the production of erythropoietin.

1. Nobelium
   Argon
2. Sodium
   Phosphorus

Nobelium is an element which is represented by the symbol No and the atomic number 102. Named after the inventor of dynamite, Alfred Nobel, the element does not have a specific use partly due to its very short half-life.

1. Zirconium
   Niobium
2. Curium
   Cadmium

Curium is an element which is represented by the symbol Cm and the atomic number 96. The element was named after Marie and Pierre Curie, researchers who were known for their work involving reactivity. Its most practical application is its involvement in X-ray spectrometers.