Next week…. • Monday: Lab 11 Periodic Trends • Tuesday: Lab 11 Analysis and Intro to Trends • Wednesday: Trends Continued • Thursday: Graded Trends Activity (Due Jan 4th) • Friday: NO SCHOOL
Essential Question • How is the periodic table arranged?
Dobereiner—Triad Model (1829) Elements in groups of 3 Could not incorporate new elements Newlands—Law of Octaves (1864) Repeating pattern every 8 elements Several known elements didn’t fit the trend History of the P.T.
Mendeleev (1869) • Father of the Periodic Table • Elements’ properties are periodic functions of their atomic mass • Grouped elements based on properties • Left space for “new” elements • Predicted properties of unknown elements
Vertically intoGroups/Families Horizontally IntoPeriods Elements are arranged:
If you looked at one atom of every element in a group/family you would see…
Each atom has the same number of valence electrons -Electrons in the outermost shell - We call these “bonding” electrons
The group 2 atoms all have 2 electrons in their outer shells Be (Beryllium) Atom Mg (Magnesium) Atom
Octet Rule • An atom is most stable with _____ electrons in the outer most energy level • Atoms either gain or lose electrons to achieve this.
The number of outer or “valence” electrons in an atom affects the way an atom bonds. • The way an atom bonds determines many properties of the element. • This is why elements within a group usually have similar properties.
If you looked at an atom from each element in a period you would see…
The period 4 atoms each have 4 electronenergy levels 4th Shell K (Potassium) Atom Kr (Krypton) Atom Fe (Iron) Atom
Divisions of the Table • Divided into regions based on general properties • Include: • Metals • Non-metals • Metalloids
Metals • Left of stairstep line • Very dense • Shiny • Solids, high melting pt. • Thermal & electrical conductors • Form + ions
Non-metals • Right of stairstep line • Low density, usually gases • Melt at low temperatures • Do NOT conduct heat or electricity
Metalloids • Have properties of both metals and non-metals • Lie along the stairstep line separating metals and nonmetals • Except Al and Po • Semi-conductors
Quick Check! • State whether the following are metals, nonmetals, or metalloids: • Potassium • Iodine • Antimony
Group Properties • The Periodic Table is divided into several groups based on the properties of different atoms.
Review • What group is phosphorus in? • What period is phosphorus in? • How many valence electrons does phosphorus have? • Is it a metal, nonmetal, or metalloid? • How many electrons does it need to gain to be stable?
http://www.lyon.edu/webdata/Users/DMcDowell/GenChem/alkalishow.htmlhttp://www.lyon.edu/webdata/Users/DMcDowell/GenChem/alkalishow.html Alkali Metals
Alkali Metals • Group 1 • Soft, silvery colored metals • 1 valence e- • Form +1 ions • Very reactive!!! • Sodium Drop: http://www.youtube.com/watch?v=MTcgo46nxNE • http://www.youtube.com/watch?v=m55kgyApYrY
Alkaline Earth Metals • Group 2 • Silvery-white metals • 2 valence e- • Form +2 ions • Fairly reactive • Found in rocks in the earth’s crust
Transition Metals • Have very similar properties • Most are conductors • Malleable/Ductile • Can form multiple ions • Fe can be 2+ or 3+
Lanthanide Series Actinide Series
Rare Earth Metals • Very Reactive • Strongly paramagnetic • Many are radioactive
Halogens • Group 17 • Most are poisonous • Gain an e- to form -1 ions • Cl2 was used as a chemical weapon during WWI and WWII
Noble Gases • Group 18 • Very unreactive • Originally believed to be inert (unreactive) • Gases at room temperature • Helium has the lowest boiling pt (-268.9oC)
Summing It Up • State which group each of the following elements belongs to and give a property of the element. • Lithium • Chlorine • Uranium • Krypton • Strontium • Chromium