Presenting… Chemistry’s Top 20

1. Presenting…Chemistry’sTop 20

2. Hydrogen: 1 H

3. Hydrogen: 1 H Over ninety percent of all the atoms in the universe are hydrogen atoms and they are the lightest atoms of all elements!Hydrogen as water (H2O) is absolutely essential to life on Earth and it is present in most life-sustaining molecules. Hydrogen burns in air to form only water as waste product. If enough hydrogen could be made from other thanfossil fuels then there might be a possibility of a hydrogen economy.

4. Helium: 2 He

5. Helium: 2 He Helium is the other very simple element that you will find with one atomic orbital. It was named after the Sun and the Latin word "helios". Even when first discovered and identified, scientists knew there were large amounts of helium in the Sun. Similar to hydrogen, helium is usually found as a gas and has no color or smell. Helium is very unreactive and is found everywhere in the universe, just like hydrogen, and is the second most common element.

6. Lithium: 3 Li

7. Lithium: 3 Li This is the first metal in the periodic table and it is a silvery colored solid when purified. Lithium is never found alone in nature. It is always bonded to other elements.Lithium is a solid and is the least dense metal. It’s only about half as dense as water. Lithium atoms tend to lose an electron to form Li+ ions. Lithium can be mixed with aluminum and magnesium for light-weight alloys, and is also used in batteries, some greases, some glasses, and in medicine.

8. Beryllium: 4 Be

9. Beryllium: 4 Be Beryllium was discovered in 1798 when a chemist (Vaquelin ) was working with emeralds. Emeralds are a precious form of the mineral beryl, [Be3Al2(SiO3)6]. It is metal and is never found alone in nature. It is always combined with other elements when found on Earth .Beryllium compounds are very toxic. Its chemistry is controlled by its tendency to lose 2 electrons to form Be2+. It is a non-magnetic metal, so it is very useful in electronics.

10. Boron: 5 B

11. Boron: 5 B Boron has properties which are borderline between metals and non-metals (semimetallic). It was isolated and named in 1808. It's a tough element to isolate because it is never found alone in nature and is always part of larger compounds in nature, appearing as a brown powder or a crystal. It is a very poor conductor of electricity. Boron compounds play important roles as light structural materials, insecticides and preservatives .

12. Carbon: 6 C

13. Carbon: 6 C Carbon is the magic element for everything on earth. All life on earth depends on carbon. It is a very stable element and is found in nearly every biological compound that makes up our bodies, systems, organs, cells, and organelles. When you breathe out, it's carbon combined with oxygen. Carbon It is found in abundance in the sun, stars, comets, and atmospheres of most planets. Carbon is found free in nature in three forms: amorphous, graphite, and diamond.

14. Nitrogen: 7 N

15. Nitrogen: 7 N Along with carbon and oxygen, nitrogen is essential in most of the compounds that allow life to exist. Nitrogen gas is colorless, odorless, and generally unreactive as a pure molecule. Its compounds are vital components of foods, fertilizers, and explosives. As a liquid it is also colorless and odorless and is a cryogenic fluid which can cause rapid freezing on contact with living tissue. Almost eighty percent of earth's atmosphere is made of nitrogen gas.

16. Oxygen: 8 O

17. Oxygen: 8 O Oxygen is the third most abundant element found in the sun. Oxygen gas (O2) is colorless, odorless, and tasteless, and is also very reactive. O2 makes up over twenty percent of the earth's atmosphere. Earth is the only planet in the solar system with enough oxygen to support life as we know it. About two-thirds of the human body, and nine-tenths of water, is made of molecules containing oxygen atoms.

18. Fluorine: 9 F

19. Fluorine: 9 F Fluorine is the most reactive of all elements! It can combine with nearly any element on Earth. Fluorine gas has a yellowish color at room temperature and is very poisonous. Fluorine is classified as a “halogen” which means “salt-former”. The most common uses of fluorine are in the production of uranium, air conditioning, refrigeration, insecticide, toothpaste, and Teflon.

20. Neon: 10 Ne

21. Neon: 10 Ne Neon is a very unreactive (“inert”) and rare gas. It is present in the atmosphere as only1 part in 65,000. Neon is a clear, odorless gas that isn't very exciting without electricity. But, in a vacuum discharge tube, neon glows reddish orange. Liquid neon has over 40 times more refrigerating capacity than liquid helium, and more than 3 times that of liquid hydrogen.

22. Sodium: 11 Na

23. Sodium: 11 Na Pure sodium is a silvery bright metal that is quite soft and putty-like. Sodium tends to give up one electron easily and, therefore, forms +1 ions (Na+). Sodium is one of the few metals that will float when it is placed in water. Its atomic mass is less that water's atomic mass. Soap is generally a sodium salt of fatty acids. The importance of common salt to animal nutrition has been recognized since prehistoric times. The most common sodium compound is NaCl (table salt).

24. Magnesium: 12 Mg

25. Magnesium: 12 Mg When purified, magnesium is a very light and silvery metal. Magnesium is the eighth most abundant element in the earth's crust , but is not found in it's elemental form in nature. Its lightness makes it perfect for use in many other metal alloys to increase strength without increasing the weight of the structure. Magnesium is also an important dietary element. Both humans and plants need small amounts of magnesium to live and be healthy. It is called a “trace metal”.

26. Aluminum: 13 Al

27. Aluminum: 13 Al Pure aluminum is a silvery-white metal with many desirable characteristics. It is light, nontoxic (as the metal), nonmagnetic and non-sparking. It is somewhat decorative. It is easily formed, machined, and cast. Pure aluminum is soft and lacks strength, but alloys with small amounts of copper, magnesium, silicon, manganese, and other elements have very useful properties. Aluminum is an abundant element in the earth's crust, but it is not found free in nature.

28. Silicon: 14 Si

29. Silicon: 14 Si Silicon is found everywhere in the universe. It is very common in the earth’s crust, but is not found by itself in nature. Silicon is typically bonded to oxygen, forming “silicates” such as sand (silica), quartz, rock crystal, amethyst, agate, flint, jasper and opal. Silicon is found also in minerals such as asbestos, feldspar, clay and mica. When purified, silicon is a metallic- looking and grayish crystal. While it might be shiny like a metal, it is actually a metalloid (semimetal)!

30. Phosphorus: 15 P

31. Phosphorus: 15 P Phosphorus is not found free in nature and is very reactive. When isolated and pure, phosphorus is clear and almost transparent. There are four common forms used today: white, black, red, and violet . Phosphorus compounds are important to living things. It is found in bones, teeth, nucleic acids (DNA and RNA), in the energy carriers (such as ATP), lipids, proteins and enzymes. Phosphorus is also one of the most important elements for plants.

32. Sulfur: 16 S

33. Sulfur: 16 S Sulfur is a pale yellow, brittle solid, which is not soluble in water. It its pure form, sulfur has a faint odor, but its compounds can be very “smelly”. Sulfur is essential to life and is a minor component of fats, body fluids, and skeletal minerals.It is found in meteorites, volcanoes, hot springs. It is recovered commercially from "salt domes" along the Gulf Coast of the USA.Sulfur dioxide is a dangerous component in atmospheric air pollution and is one of the factors responsible for acid rain.

34. Chlorine: 17 Cl

35. Chlorine: 17 Cl Chlorine is not found in a free state in nature. Cl2 is a greenish-yellow gas which reacts with nearly all elements. Chlorine gas irritates mucous membranes of the respiratory tract and is likely to be fatal after a few deep breaths. It was used as a war gas in 1915. Chlorine is the second member of the “halogen” family and tends to form salts such as NaCl (solid or in seawater).

36. Argon: 18 Ar

37. Argon: 18 Ar Argon is a colorless and odorless gas making up about 1% of the atmosphere. Argon is very “inert” and is one of the noble gases. It is not known to form true chemical compounds. Argon is heavier than air and less reactive than nitrogen gas. It is therefore used to fill light bulbs, to extinguish fires, and to prevent fires during welding. It is also used in museums to protect and preserve old documents.

38. Potassium: 19 K

39. Potassium: 19 K Potassium is never found free in nature. It is an extremely reactive and electropositive metal. It oxidizes very rapidly in air and it usually catches fire when reacting with water. It has a very low density and is soft & easily cut with a knife. It is silvery in appearance immediately after a fresh surface is exposed. Potassium is an essential constituent for plant growth and it is found in most soils. It is also a vital element in the human diet.

40. Calcium: 20 Ca

41. Calcium: 20 Ca Calcium is a grey silvery metal. It is an essential constituent of leaves, bones, teeth, and shells. Calcium is the fifth most abundant element in the earth's crust (more than 3%).Calcium does not occur as the metal itself in nature. It occurs commonly on earth in various forms of its carbonate. (Ex: chalk, limestone, marble, and calcite.) Its compounds are used to make plaster, quicklime, cement, and electronic materials.

42. Sir Humphrey Davy(1778-1829) Accomplished and well-respected chemist who discovered the elements sodium, potassium, magnesium, calcium, boron, strontium, and barium.

43. References http://www.webelements.com/ http://www.chem4kids.com/files/elem_intro.html http://www.encyclopedia.com/topic/Sir_Humphry_Davy.aspx