Unit 2: Atoms and Bonding
2.76 Periodic Table Trends:
6. Families
Textbook ch 7.7 -7.8
Big Idea 1: The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangements of atoms. These atoms retain their identity in chemical reactions. Students will be able to demonstrate understanding by laboratory investigation, analysis of data and creation of models.
SWBAT:• Correlate the atomic properties of
elements based on family with their chemical reactivity and physical properties
Learning Objectives:
Alkali Metals Group 1A elements Alkali metals are NEVER found pure in
nature; they are too reactive (ALL react with water even moisture in the air)
Metal +H2O metal hydroxide + H2(g)
The reaction above very exothermic and can produce fire or explosion.
Reactivity of these elements increases down the group
Silvery appearance, soft enough to cut with knife
Also have low 1st ionization energies. Most reactive metal on periodic table
is in this group- Cs- cesium Fr- most unstable of the naturally
occurring elements , highly radioactive
Potassium, K reacts
with water and must be stored
in kerosene
Alkaline Earth Metals• Alkaline earth metals are less reactive than alkali
metals• Alkaline earth metals are not found pure in nature; they
are too reactive• 1st and 2nd ionization energies low• Harder, denser , and melt at higher temp than alkali
metals– Be does not react with water or steam– Mg reacts slightly with water and more readily with
steam– Ca and below follow this pattern: Ca +H2O Ca(OH)2
+ H2(g)
Uses:– Mg = sea water, light weight alloys for
planes and trucks– Be = dark green form is Emerald. Light
blue/green from is Aquamarine.– Sr = fireworks and flares
Transition
Metals
Copper, Cu, is a relatively soft metal, and a very good electrical conductor.
Mercury, Hg, is the only metal that exists as a liquid at room temperature
Lanthanide & Actinide Seriesalso called inner transition
metals• F-block elements• Actinides:
– ALL are unstable and radioactive
• Lanthanides:– shiny- reactive
metals– readily available
thanks to technology
Poor Metals• Al,Ga,In,Sn,Tl,Pb,Bi,Po are poor metals.• They are not very reactive and weakly posses
properties • FYI: Note there is some debate about Po…some
resources say it’s a semimetal …American Chemical Society calls it a poor metal (acs.org) . I won’t test you on this one.
Properties of Metalloids or Semimetals They have properties of both metals and nonmetals.
Metalloids are more brittle than metals, less brittle than most nonmetallic solids
Metalloids are semiconductors of electricity
Some metalloids possess metallic luster
Silicon, Si – A Metalloid Silicon has metallic luster
Silicon is brittle like a nonmetal
Silicon is a semiconductor of electricityOther metalloids include:
Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te
Nonmetals
• Nonmetals is a family on the periodic table that includes the nonmetals that didn’t already fit in a different family. (halogens or noble gas)
• Not to be confused when comparing all nonmetals to all metals by general characteristics (last PPT)
Nonmetals Nonmetals are poor conductors of heat and electricity
Nonmetals tend to be brittle
Many nonmetals are gases at room temperature
Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
H 11.00797Hydrogen
Examples of Nonmetals
Sulfur, S, was once known as “brimstone”
Microspheres of phosphorus, P, a reactive nonmetal
Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure
Halogens (a specific type of non metal
Halogens are never found pure in nature; they are too reactive Halogens in their pure form are diatomic molecules (F2, Cl2, Br2, and I2)
Note some debate about At…some resources place it as a metal… unstable and only micrograms have been produced so extensive testing impossible!- I won’t test you on this one.
Chlorine is a yellow-green poisonous gas
Noble Gases (a specific type of nonmetal)
Noble gases are ONLY found pure in nature – they are chemically unreactive (mostly…see next slide)
Colorless, odorless and unreactive; they were among the last of the natural elements to be discovered Neon lights
Neon gas + electricity
Noble Gases have been forced to react in lab
• In 1962 1st noble gas compound synthesized by Neil Bartlett
Today: • Xe forms three compounds:
– XeF2
– XeF4 (at right)– XeF6
• Kr forms only one stable compound:– KrF2
• The unstable HArF was synthesized in 2000.
XeF4 crystals
References
Our textbook: Brown, Lemay et all. AP edition chemistry, 13th edition, 2015
www.sciencegeek.net/Chemistry
I modified the original PPTs to fit our needs in AP Chemistry.
Top Related