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Transcript of Metalloids
=from Greek word "
" or "
" meaning metal and "
" meaning sort.
="sort of metal"
=chemical elements that have properties of both non-
metals and metals
=In the periodic table of elements, metalloids form a step ladder that acts as a transition or division line from metals and non-metals. These elements can be found on the p-block.
Properties of Metalloids
A. Physical Properties
3. Can be shiny or dull
4. Solid at room temperature
B. Chemical Properties
1. Moderate electronegativity and
2. For the elements to the right, they tend to gain electrons during chemical reactions and the opposite for those on the left.
Though known for thousands of years, Boron was discovered by Sir Humphry Davy, Joseph Louis Gay-Lussac, Louie Jacques Thenard in 1808. When Davy produced enough boron to be considered an element using his experiment, he named it
. Gay-Lussac and Thenard found boron through the reaction of boric acid with potassium. Jons Jakob Berzelius distinguished boron as an element in 1824. There are a lot of uses for boron. Borosilicate glass is good at resisting thermal shock and is used for laboratory glassware, cooking, and cookware. Just like its fellow metalloids, boron is also used for semiconductors. When heated, boron gives off a distinguishable shade of green making it suitable for green fireworks.
Atomic weight: 10.811
Melting point: 2076 C
Boiling point: 3927 C
Origin of Name: Arabic word "
and Persian word
There were many attempts to isolate silicon. After trying to isolate it, Sir Davy proposed the name "silicium" from Latin word silex or silicis for flint and added "-ium" believing it was metal. Then, Gay-Lussac and Thenard failed to separate silicon from their experiment. Silicon got its present name from Thomas Thomson. He believed silicon is nonmetal like boron. Silicon was ,then, discovered by Jons Jakob Berzelius, by using Gay-Lussac's methods. Credits were given to him. 31 years later, Deville prepared the common form of crystalline silicon. Silicon is the second most abundant element in the Earth's crust and the seventh in the universe. Two allotropes of silicon is formed at room temperature: amorphous and crystalline. Amorphous exists as a brown powder and crystalline has metallic luster and a grayish color. When added with other elements, these crystals can be used for silicon chips, transistors, solar cells, rectifiers, and micro chips.
Atomic Weight: 28.0855
Color:dark grey with a tinge of blue
Melting Point: 1414 C
Boiling Point: 2900 C
Origin of Name: Latin "
" or "
In 1869, Dmitri Mendeleev predicted three elements that would fill the gap in his periodic table. He called it ekasilicon because of its postion. In mid-1885, Clemens Wrinkler was able to isolate germanium from mineral argyrodite. He named it after his hometown, Germany. Germanium is widely used in the semiconductor industry. When added with other elements, it forms transistors for electronic devices. It is also used for alloys and in fluorescent lamps. It can also be found in optical intruments and infrared detectors.
Atomic Weight: 72.64
Melting Point: 938.25 C
Boiling Point: 2833 C
Origin of Name: Named after the country of Germany
Arsenic compounds has been mined since early Chinese, Greek, and Egyptian civilazations. It is said that arsenic, itself, was first obtained by Albertus Magnus in 1250. Often, Arsenic can be found in minerals arsenopyrite, realgar, and orpiment. Arsenic can be obtained from arsenopyrite by heating it. Arsenic is poisonous. This is why it is used in insecticides, rat poisons and, wood preservers. Gallium arsenide is important in the semiconductor industry.
Atomic Weight: 74.92160
Color: metallic gray
Melting Point: 817 C
Boiling Point: 614 C
Origin of Name: Latin word "arsenicum" and Greek "arsenikon" meaning yellow orpiment.
The element Antimony has been known since ancient times. It occurs freely in the nature but is often found on the ores of stibnite and valentinite. Nicholas Lemery was the first to study Antimony. Pure antimony was first described by Swedish scientist, Anton von Swab. Antimony is very brittle and is a poor conductor. It is used in diodes and infrared detectors It can also be used in alloys with lead. Antimony compounds is used in ceramic enamel and in glass and pottery. Ancient Egyptians use antimony for black eye make-up.
Atomic Weight: 121.760
Color: silver/lustrous gray
Melting Point: 630.63 C
Boiling Point: 1587 C
Origin of Name: Greek "anti+monos" meaning "not alone" and Sb from historic name, Stibium
Tellurium was first discovered by Franz Joseph Moller von Reichenstein in gold ores in 1782. In 1798, tellurium was named by Martin Heinrich Klaproth who isolated it. It is often found in sylvanite, calaverite, and, krennerite ores. Tellurium is widely used in metallurgy especially in iron, copper, and lead alloys. It is also used as a semiconductor. It is used to color glass. It is also used in far infrared detectors.
Atomic Weight: 127. 60
Melting Point: 449. 51 C
Boiling Point: 998 C
Origin of Name: Latin word
"tellus" meaning goddess of the earth
Polonium was discovered by Marie Sklowdowska Curie in 1898. Polonium was the first element Marie Curie found. She discovered it while seeking the cause of the radioactivity of pitchblende. Polonium is usually made by bombarding bismuth-209 with neutrons in a nuclear reactor. This produces bismuth-210. It turns into polonium-210 through beta-decay. It is also used in anti-static brush, which is used to discharge any static electricity in the are of the brush.
Atomic Weight: 209
Melting Point: 254 C
Boiling Point: 962 C
Origin of Name: /named after Curie's hometown, Poland
There are also other element that are sometimes classified as metalloids such as Carbon, Aluminum, Selenium and Astatine because they have properties that can be compared to metalloids. The elements mentioned below are the commonly known metalloids.