Transcript Mixed groups - Cloudfront.net

Bell Work
Using your textbook, define the
following terms:
• Metalloid
• Semiconductor
• Allotrope
Section 3
Mixed Groups
Objectives
• Distinguish among metals, nonmetals, and
metalloids
• Describe the nature of allotropes
• Describe how the properties of metalloids define
them as semiconductors
Properties of Metalloids
• Form ionic and covalent bonds with other elements
• Have metallic and nonmetallic properties
• Semiconductor: def. element that conduct electric current
under certain conditions
• Mixed groups- 13,14,15,16,17  contain a combo of metals,
nonmetals, and metalloids
Boron Group
• All have 3 electrons in outer shell
BORON, B - metalloid
• Borax used in some laundry
products to soften water
• Boric acid mild disinfectant
• Boranes used in jet and rocket
fuel
Boron Group conti.
ALUMINUM, Al – metal
•most abundant metal in Earth’s crust
•strong, lightweight
•used in cooking pans, siding, airplanes
Carbon Group
• 4 electrons in outer shell
• Allotropes- def. different forms of the same
element; different molecular structure
Carbon, C – nonmetal
• found in all organic compounds
• CO2
• natural gas
• coal & oil
Use Phone…
• Soft lead metal was once used for writing black marks on
paper. Graphite mixed with clay is less toxic and has
replaced lead in pencils for writing.
• The term graphite comes from the Greek word
____________ which means ___________________.
Graphein
To write
Allotropes in Carbon
Diamond- clear, extremely hard
• each C is bound to 4 C atoms forming tetrahedrons
Graphite- black powder consisting of hexagonal layers of C
atoms where each C is bound to 3 C
Buckminsterfullerene- soccer ball shape
• used to make tiny tubes nanotubes
•
https://www.brainpop.com/technology/scienceandindustry/nanotechnology/
Carbon group conti.
Silicon, Si - metalloid
•2nd most abundant element in earth’s crust
•most found in sand, rocks, and soil
•2 allotropes:
1.hard, gray substance
2.brown powder
•Used in electronic devices ex: computer
chips
Germanium, Ge – metalloid
•Semiconductor used in cell phone and other
electronics
Tin, Sn- metal
• Coats other metals to
prevent corrosion
• combines w/ other
metals to produce
bronze
Lead, Pb- metal
• once used in paint and
pencils TOXIC
Nitrogen Group
• 5 electrons in the outer shell
• Tend to share electrons and form
covalent compounds w/ other
elements
Nitrogen, N – nonmetal
• 4th most common element in
body
• Used to produce nitrates (NO3-)
and ammonia found in fertilizers
Phosphorus, P- nonmetal
• 3 allotropes
• water softener, fertilizers, match
heads, fine china
Nitrogen Group conti.
• Antimony, Sb (metalloid)& Bismuth, Bi (metal)used to lower melting point in other metals
• Bismuth used in automatic fire-sprinkler heads
Oxygen Group
• 6 electrons in outer shell
Oxygen, O - nonmetal
• 21% air, diatomic molecule O2 (needed for
respiration)
• electrical storm O2 ozone molecules O3
(protection from Sun’s radiation)
Oxygen Group cont.
Sulfur, S – nonmetal
•several allotropes: different
shaped crystals & noncrystalline
forms
•Bad smell- rotten eggs!
•pigments in paint
•Sulfuric acid fertilizers
Selenium, Se – nonmetal
•need trace amounts in diet for
making antioxidant enzymes
Tellurium, Te – metalloid
•brittle, mildly toxic, rare,
silver-white; alloy, no biological
function
Polonium, Po – metalloid
•Rare radioactive element
HOMEWORK
• Chapter Review Worksheet
Synthetic Elements
• By smashing existing elements with
particle accelerated in a heavy ion
accelerator, nuclear scientists have
been
creating elements typically not
found on
Earth.
• Except for Technetium 43 and Promethium 61,
each synthetic elements has more than 92
protons (transuranium elements).
• Neptunium-> bombarding U w/ neutrons; ½
disintegrate in 2 days to form plutonium (highly
toxic/used in bombs)
• Pu-> changed to Americium (used in smoke
detectors)
Transuranium Elements
•
•
•
•
•
Unstable
Synthetic
Many disintegrate quickly
Towards the bottom of the periodic table
More than 92 protons
Why make elements?
• Medical applications
• Weapons applications
• By studying how these elements form and disintegrate,
gain understanding of forces holding the nucleus
together. When atoms disintegrate = radioactive
• Scientists are seeking stability in synthetic elements