By: Melissa M, Mackenna P, Landon B, Zachary K! Block: 7

About Metalloids

The metalloids include Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), and Polonium (Po).

Metalloids are the elements found along the stair-step line that separates metals from nonmetals. This line is drawn from between Boron and Aluminum to the border between Polonium and Astatine.The only exception to this is Aluminum which is classified under "Other Metals”. Metalloids have properties of both metals and non-metals.


Boron: Was not officially discovered until 1808 by Sir Humphry Davy, Joseph-Louis Gay-Lussac and Louis Jaques Thenard.

Silicon: Silicon was looked at for the first time by Jons Berzelius in 1823

Germanium: This element was predicted by Clemens Winkler in 1886

Arsenic: The dicoverer of this element is unknown and the date of discovery was known to the anicents.

Polonium: Polouium was the first element discovered by Marie and Pierre Curie in 1898

Tellurium: Tellurium was founded by Franz Muller Von Reichenstein 1782.

Number of Valence Electrons: Every Metalloid has valence eletrons. However, Boron is the only metalloid that has 3 valence electron. Silicon and Germanium have 4 electrons. Also Arsenic and Antimony both have 5 valence electrons. Last but not least the last two Metalloids Tellurium and Polonium have 6 valence electrons.

Boiling and Melting Points of Metalloids:

Boron- Melting Point- 2300C Boiling Point- 2550C

Silicon- Melting Point- 1410C Boiling Point- 2355C

Germanium- Melting Point- 937C Boiling Point- 2830C

Arsenic- Melting Point- 81C Boiling Point- 613C

Antimony- Melting Point- 630C Boiling Point- 1750C

Tellurium- Melting Point- 449C Boiling Point- 990C

Polonium- Melting Point- 254C Boiling Point- 962C

Health and Evironmental Concerns:

Boron has an environmental concerns, when animals are exposed to boron during pregnancy their offspring may suffer from birth defects or delayed development.

Silicon is an health concern considering with lung cancer.

Arsenic causes skin cancer, liver cancer, and lymphatic cancer.

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Everyday examples that have metalloids in them !

Boron: Fireworks

Silicon: Computer microchips

Germanium: Wide angle camera lenses

Arsenic: Mirrors

Antimony: Batteries, Mascara, pottery

Tellurium: Glass and ceramics

Polonium: A brush that has dust practicals with Polonium in it, that helps clean cameras that are used a lot (for examples movie producers use them to help clean the camera for a good view during the movie)

What metalloids react with!

Metalloids acts as a nonmetal when reacting with sodium yet as a metal when reacting with fluorine

Metals, Nonmetals, and Metalloids (4.3 - 4.4)

13:03 is the time when they talk about mettaloids in the video above