Transcript Group 16 Elements

Group 16 Elements
By Zach Bindell, Val Chin, & Kevin Pugh
Chalcogens
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Each element contains six valence electrons
Each element forms 2- ions
Located in the p block of the periodic table
The term chalcogen was first used by the
Wilhelm Blitz research group at the
University of Hannover in Germany
Chalcogens
● The term calcogen in greek is literally “copper
former” but can be translated to “ore former” or,
more commonly, “chalk former”
● The characteristics of chalcogens vary
dramatically because the group crosses the line
between metals and nonmetals
● The elements are mostly solids at room
temperature, excluding oxygen, which is a gas
Oxygen
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Discovered in 1774 by Joseph Priestly in Wiltshire
England after he did experiments with HgO (mercuric
oxide). He found out that by exposing the chemical to
sunlight it liberated a gas that is now recognized as pure
oxygen (O2).
The name comes from the greek ‘oxy genes’ meaning
‘acid forming’.
Oxygen is a diatomic element naturally found as a
colorless, odorless gas. It is also highly flammable.
It makes up 21% of the Earth’s atmosphere, 49% by
mass of the Earth’s crust, and ⅔ of the human body.
The oxygen content in the atmosphere is at the perfect
concentration so organisms don’t die of asphyxiation or
spontaneously combust.
O16 is the most abundant isotope (99.762%)
Used in the production of a wide variety of chemicals
including nitric acid and hydrogen peroxide.
Used most commonly in the steel industry for welding
and cutting metal.
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Sulfur
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S
General Characteristics
○ Assryian texts from 700-600B.C. state sulfur is a “product of the riverside”
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○ Sulfur deposits were found along the rivers.
SULFUR
○ Discovered in Northern Iraq
Physical Characteristics
○ Solid at room temperature
○ Nonmetal
○ Yellow brittle crystals
○ Density = 2.07g/cm3
○ Melting Point = 115.21oC, Boiling Point = 444.62oC
Unique Facts
○ Used for organic insecticides, preservatives for dried fruits, and fertilizers
○ Extracted from the Earth by Frasch processes.
Selenium
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Discovered in 1817 by Jöns Jacob Berzelius after
observing a red-brown sediment collected as a bi
product of sulfuric acid.
The name comes from ‘selene’ the Greek name for
moon.
Selenium is a metalloid naturally found in either a
silvery metal or a red powder.
It is an essential trace element in humans however in
excess can act as a carcinogen.
Most abundant isotopes: 80Se(49.6%), 78Se(23.7%),
76Se(9.4%).
Used as an additive to glass to make it clear.
Used in photocells, solar cells, and photocopiers
because it is useful in converting light energy to
electrical energy.
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Tellurium
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Te
General Characteristics
○ Discovered by Franz Joseph Miller von Reichstein in Romania, 1783
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TELLURIUM
○ Found in gold ores
○ He was intrigued by the metallic sheen in gold ore and discovered Tellurium
Physical Characteristics
○ Solid at room temperature
○ Grey powder
○ Density = 6.232g/cm3
○ Melting Point = 449.51oC, Boiling Point = 988oC
Unique Facts
○ Used with copper and stainless steel to improve machinability
○ Very toxic metalloid
○ If workers mining Tellurium are exposed to tellurium, they get “tellurium breath”
that smells like garlic breath.
Polonium-Po
● Named for the country of Poland, where it was discovered
● A silvery grey radioactive semimetal which is a solid at room
temperature
● Melting point: 254°C, 489°F
● Boiling point: 962°C, 1764°F
● Density: 9.32 g/cm3
● Used as an alpha emitter
● Used as a source of heat in space equipment
● Very rare natural element
● Mendeleev predicted Po would exist because of a missing space
on his periodic table
● In 1898 Marie Curie and husband Pierre extracted some Polonium
from pitchblende (uranium oxide, U3O8)