Chalcogens

__**Chalcogens**__
===Chalcogens are the chemical elements in group 16, also known as group VI and the oxygen family. The group contains 5 elements including oxygen (O), sulphur (S), selenium (Se), tellurium (Te) and polonium (Po). The name of this group Chalcogens comes from the Greek word //chalcos// which means ‘ore formers’ because they can all be found in copper ores.===

** Oxygen **

 * Symbol:** O
 * Atomic Number:** 8
 * Atomic Mass:** 15.9994 amu
 * Melting Point:** -218.4 °C (54.750008 K, -361.12 °F)
 * Boiling Point:** -183.0 °C (90.15 K, -297.4 °F)
 * Number of Protons/Electrons:** 8
 * Number of Neutrons:** 8
 * Classification:** [|Non-metal]
 * Crystal Structure:** Cubic
 * Density at 293 K:** 1.429 g/cm3
 * Color:** colorless

=
Oxygen is the most commonly found element on Earth, making up around 50% of all elements on Earth’s surface. At room temperature oxygen is a gas which has no smell, taste or colour while as a liquid and solid has a whitish blue colour. Oxygen is highly reactive and when formed with other substances to make an oxide is called oxidation. Examples of oxidation are respiration in animals and plants and when items are burned in the air called combustion. It helps form numerous amounts of compound groups from acids to phosphates as well as proteins and fats.======
 * ** Isotope ** || ** Half Life ** ||
 * O-15 || 122.2 seconds ||
 * O-16 || Stable ||
 * O-17 || Stable ||
 * O-18 || Stable ||

**Symbol:** S

 * Atomic Number:** 16
 * Atomic Mass:** 32.066 amu
 * Melting Point:** 112.8 °C (385.95 K, 235.04001 °F)
 * Boiling Point:** 444.6 °C (717.75 K, 832.28 °F)
 * Number of Protons/Electrons:** 16
 * Number of Neutrons:** 16
 * Classification:** [|Non-metal]
 * Crystal Structure:** Orthorhombic
 * Density at 293 K:** 2.07 g/cm3
 * Color:** yellow

=
Ranking as the 13th most common element in the Earth’s crust, sulfur is a nonmetallic element and has no smell or taste. Sulfur exists naturally as sulfates and metallic sulfides in its elemental state but can also be found in organic ones. It is most abundantly found in North America making the U.S own 26% of the resources shares. Sulfur is used to make things like dyes, battery acids and fertilizers as well as chemicals like sulfuric acid. ====== []
 * ** Isotope ** || ** Half Life ** ||
 * S-32 || Stable ||
 * S-33 || Stable ||
 * S-34 || Stable ||
 * S-35 || 87.2 days ||
 * S-36 || Stable ||

**Symbol:** Se

 * Atomic Number:** 34
 * Atomic Mass:** 78.96 amu
 * Melting Point:** 217.0 °C (490.15 K, 422.6 °F)
 * Boiling Point:** 684.9 °C (958.05005 K, 1264.8201 °F)
 * Number of Protons/Electrons:** 34
 * Number of Neutrons:** 45
 * Classification:** [|Non-metal]
 * Crystal Structure:** Hexagonal
 * Density at 293 K:** 4.79 g/cm3
 * Color:** gray

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Selenium is derived from the Greek word //selēnē// which means the Moon and is the 34th most commonly found element in Earth’s crust. Discovered in 1817 by Jöns Jakob Berzelius it has 6 natural isotopes and a large amount of allotropes. Due to its manner of conducting electricity to one magnetic or electric pole it is commonly used in electrical rectifiers. Although very important to warm blooded creatures it can also be harmful if too much is taken into the body.======
 * ** Isotope ** || ** Half Life ** ||
 * Se-73 || 7.15 hours ||
 * Se-74 || Stable ||
 * Se-75 || 119.78 days ||
 * Se-76 || Stable ||
 * Se-77 || Stable ||
 * Se-78 || Stable ||
 * Se-79 || 65000.0 years ||
 * Se-80 || Stable ||
 * Se-82 || Stable ||

[]

**Symbol:** Te

 * Atomic Number:** 52
 * Atomic Mass:** 127.6 amu
 * Melting Point:** 449.5 °C (722.65 K, 841.1 °F)
 * Boiling Point:** 989.8 °C (1262.95 K, 1813.64 °F)
 * Number of Protons/Electrons:** 52
 * Number of Neutrons:** 76
 * Classification:** [|Metalloid]
 * Crystal Structure:** Hexagonal
 * Density @ 293 K:** 6.24 g/cm3
 * Color:** silverish

=
The name is derived from the Latin word //tellus //meaning “earth” and was found by Franz Joseph Müller von Reichenstein. Ranked 37th most abundant element in the Earth’s crust and can be commonly found with copper, silver, gold, zinc, cobalt and many others. Mainly used as semiconductors on alloys. ======


 * ** Isotope ** || ** Half Life ** ||
 * Te-119 || 4.69 days ||
 * Te-120 || Stable ||
 * Te-121 || 16.8 days ||
 * Te-121m || 154.0 days ||
 * Te-122 || Stable ||
 * Te-123 || 1.3E12 years ||
 * Te-123m || 119.7 days ||
 * Te-124 || Stable ||
 * Te-125 || Stable ||
 * Te-125m || 58.0 days ||
 * Te-126 || Stable ||
 * Te-127 || 9.4 hours ||
 * Te-127m || 109.0 days ||
 * Te-128 || Stable ||
 * Te-129 || 1.16 hours ||
 * Te-129m || 33.6 days ||
 * Te-130 || 2.5E21 years ||
 * Te-131 || 25.0 minutes ||
 * Te-131m || 1.35 days ||
 * Te-132 || 3.26 days ||
 * Te-133 || 12.4 minutes ||
 * Te-133m || 55.4 minutes ||
 * Te-134 || 41.8 minutes ||

[]

** Polonium **

 * Symbol:** Po
 * Atomic Number:** 84
 * Atomic Mass:** (209.0) amu
 * Melting Point:** 254.0 °C (527.15 K, 489.2 °F)
 * Boiling Point:** 962.0 °C (1235.15 K, 1763.6 °F)
 * Number of Protons/Electrons:** 84
 * Number of Neutrons:** 125
 * Classification:** [|Metalloid]
 * Crystal Structure:** Monoclinic
 * Density @ 293 K:** 9.4 g/cm3
 * Color:** Silver-grey

=
Discovered in 1898 by Marie Curies, polonium is a radioactive metal with a silver-grey colour and was named after her country Poland. It has many isotopes with lifespans ranging from 1 second to 102 years. It burns in the air creating polonium oxide and when it reacts with halogens makes tetrahalides.======
 * ** Isotope ** || ** Half Life ** ||
 * Po-206 || 8.8 days ||
 * Po-207 || 5.8 hours ||
 * Po-208 || 2.89 years ||
 * Po-209 || 102.0 years ||
 * Po-210 || 138.38 days ||
 * Po-211 || 0.51 seconds ||
 * Po-212 || 0.29 microseconds ||
 * Po-213 || 4.0 microseconds ||
 * Po-214 || 163.7 microseconds ||
 * Po-215 || 1.78 milliseconds ||
 * Po-216 || 0.14 seconds ||
 * Po-218 || 3.1 minutes ||

[]

References:
Bentor, Y N.d., //Periodic Table: Sulfur//, Pair Networks, accessed 13 October 2011, [] Bentor, Y N.d., //Periodic Table: Selenium//, Pair Networks, accessed 13 October 2011, [] Bentor, Y N.d., //Periodic Table: Tellurium//, Pair Networks, accessed 13 October 2011, [] Bentor, Y N.d., //Periodic Table: Polonium//, Pair Networks, accessed 13 October 2011, [] || Banks, C N.d., //Chalcogens//, Advameg. Inc., accessed 11 October 2011, []. Kvaran, A N.d., //Oxygen//, Advameg. Inc., accessed 11 October 2011, []. Wen, G N.d., //Sulfur//, Advameg. Inc., accessed 13 October 2011, []. Harwood, J N.d., //Selenium//, Advameg. Inc., accessed 13 October 2011, []. Crawford & Klapotke, M & T N.d., //Tellurium//, Advameg. Inc., accessed 13 October 2011, []. Sherk, S N.d., //Polonium//, Advameg. Inc., accessed 13 October 2011, [] || . ||==
 * Bentor, Y N.d., //Periodic Table: Oxygen//, Pair Networks, accessed 13 October 2011, [].