Unit 2: Atoms and Bonding 2.76 Periodic Table Trends: 6. Families Textbook ch

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 +H 2 O metal hydroxide + H 2(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 1 st 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 metalsAlkaline earth metals are less reactive than alkali metals Alkaline earth metals are not found pure in nature; they are too reactiveAlkaline earth metals are not found pure in nature; they are too reactive 1 st and 2 nd ionization energies low1 st and 2 nd ionization energies low Harder, denser, and melt at higher temp than alkali metalsHarder, 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 +H 2 O Ca(OH) 2 + H 2(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 Series also 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 electricity Other 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 Hydrogen

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 (F 2, Cl 2, Br 2, and I 2 )  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 st noble gas compound synthesized by Neil Bartlett Today: Xe forms three compounds: – –XeF 2 – –XeF 4 (at right) – –XeF 6 Kr forms only one stable compound: – –KrF 2 The unstable HArF was synthesized in XeF 4 crystals

References Our textbook: Brown, Lemay et all. AP edition chemistry, 13 th edition, I modified the original PPTs to fit our needs in AP Chemistry.