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Note taking guide: The Periodic Table – How’s it put together
Essential Questions:
- Who figured out the periodic table and how is it organized?
- What can the periodic table tell us?
What is the periodic table?
•The periodic table is an organized arrangement of the
•Over time, and as more elements were discovered, scientists noticed of properties among elements
•They tried to the elements by these properties
Who created it?
JOHANN DOBEREINER (1829) -
•Classified some elements into groups of , which he called triads
•The elements in a triad had similar chemical properties and orderly physical properties
•One element in each triad had properties intermediate of the other two elements
•Examples:
•Cl, Br, I
•Ca, Sr, Ba
JOHN NEWLANDS (1863) -
•Arranged elements in order of
•Noticed that certain properties repeated every element
•Elements should be arranged in “octaves” (like in music)
•His law of octaves failed beyond the element calcium
•His claim was dismissed out of hand
•But this idea of “repeating 8’s” will re-surface!
DMITRI MENDELEEV (late 1800’s)
•He is credited with “inventing” the periodic table, although other folks were also doing similar work around the same time
•He arranged the known elements by increasing
•When arranged this way, he noticed that properties did repeat
•He left to keep elements properly aligned by their properties
•He felt that the blank spaces would someday be occupied by elements that had not yet been discovered
•He predicted the properties of those elements – his predictions were remarkably accurate
•In spite of his great achievement, problems arose when new elements were discovered and more accurate atomic weights determined
•Examples:
•Ar and K
•Co and Ni
•Te and I
•Th and Pa
HENRY G.J. MOSELEY (1913)
•The old arrangement was not perfect – some elements just didn’t fit
•Improved the periodic table by arranging elements by instead of atomic mass
•For the most part, atomic masses also increase, although there are some (examples are cobalt and nickel)
•The new arrangement corrected the problems from the old version
•Current arrangement of periodic table is by atomic number
•Henry Moseley was killed by a sniper in 1915 during World War I (Gallipoli, Turkey)
•Because of this, the British government changed its policy and did not allow “prominent and promising scientists” to enlist for combat duty in the armed forces during World War II
THE PERIODIC LAW
•When elements are arranged in order of increasing , there is a of their physical and chemical properties
EXAMPLE PERIODIC TABLE ENTRY
Note that the atomic number is a whole # and the atomic mass is a decimal #
NOMENCLATURE OF ELEMENTS – CHEMICAL SYMBOLS
•Could be the 1st letter of the element – H=hydrogen
•May need the 2nd or another letter of the element – C=carbon, so what about cobalt or calcium? Needed 2nd letter. What about chlorine? 6 elements have “C” as 1st letter!
•Some derived from name – Au=gold (aurum = shining dawn)
•Some named to honor (Cm=curium for Marie Curie)
•Some named for (U=uranium, Np=neptunium, Pu=plutonium)
•Some named for (Eu = Europium, Ytterby in Sweden has four elements named for it: Tb = terbium, Y = yttrium, Er = erbium, Yb = ytterbium)
•Some named for (Cs = cesium because it imparts a blue color to a flame, caesius = sky blue)
•Some named using rules established by an international committee
•First letter is ALWAYS
•Second letter is ALWAYS
Metals, Non-Metals, Metalloids
•That heavy stair-step line separates the metals from the non-metals
•The elements that straddle the line are called “metalloids”
Metals
•Metals are good of heat and electricity
•Metals are
•Metals are (can be stretched into thin wires)
•Metals are (can be pounded into thin sheets)
•A chemical property of metal is its reaction with water, which results in corrosion
Non-metals
•Non-metals are of heat and electricity
•Non-metals are or malleable
•Solid non-metals areand break easily
•They are (non-lustrous); they do not reflect light
•Some non-metals are gases (O, N, Cl); some are brittle solids (S); one is a fuming dark red liquid (Br)
Metalloids
•Metalloids (metal-like) have properties of metals and non-metals
•Some of the metalloids are . This means that they can carry an electrical charge under special conditions. This property makes metalloids useful in computers and calculators
•They are that can be shiny or dull
•They conduct heat and electricity better than non-metals but not as well as metals
•They are and
Rows on the periodic Table
•Each horizontal row of the periodic table is called a
–There are 7 periods
–The elements in a period are alike in properties
–The properties change greatly across even given row
–The first element in a period is always an extremely ; the last element in a period is always an
Columns on the Periodic Table
•The vertical columns of elements on the periodic table are called or
–The elements in any group/family of the periodic table have similar, but not identical, and properties
–Groups/Families have names in addition to numbers
–Groups/Families are numbered from 1-18 (left-right) or I-IIA, B, III-VIIIA (left-right)
–The elements in each column have the same number of electrons in the outermost energy level or shell (one to eight → remember John Newland’s “law of octaves”?)
STOP – POETRY ASSIGNMENT & ELEMENTS INVESTIGATION LAB
ORGANIZING THE TABLE BY GROUP OR FAMILY
Group 1: ALKALI METALS
•very reactive that do not occur freely in nature
•malleable, ductile, good conductors of heat and electricity.
•can explode if they are exposed to water
•The alkali metals form compounds that are similar to each other.
•Alkali metals each have valence electron
•This electron is removed when alkali metals react.
•The easier it is to remove an electron, the the atom is.
•TREND: Reactivity of alkali metals as you go the group.
Group 2: ALKALINE EARTH METALS
•
•very reactive
•not found free in nature
•Alkaline Earth metals each have valence electrons
•These electrons are removed when alkaline earth metals react.
•The easier it is to remove an electron, the the atom is.
•TREND: Reactivity of alkali metals as you go the group.
Group 3-12: TRANSITION METALS
•ductile and malleable, and conduct electricity and heat
•iron, cobalt, and nickel, are the only elements known to produce a magnetic field.
•Include Rare Earth Metals (2 rows at bottom that are pulled out)
Group: 13-16 BORON, CARBON, NITROGEN AND OXYGEN FAMILIES
•Named after the of each family
•These elements are usually referred as either metals, metalloids or non metals rather than their family names
- P-block METALS
•are ductile and malleable
•are solid, have a high density,
Group 17: HALOGENS
•"halogen" means and compounds containing halogens are called "salts"
•exist in all three states of matter
•Fluorine is the of the halogens because its outer energy level is closest to the nucleus.
•The reactivity of the halogens down the group as the outer energy levels of each element’s atoms get f from the nucleus.
Group 18: NOBLE GASES
•do not form compounds
•Happy/Inert Elements (Full outer shells)
•Neon and the elements below it in Group 18 have eight electrons in their outer energy levels.
•Their energy levels are stable, so they do not combine easily with other elements.
•At one time these elements were thought to be completely unreactive, and therefore became known as the .
•When chemists learned that some of these gases can react, their name was changed to .
•They are still the most stable element group.
STOP – COLOR THE PERIODIC TABLE ACTIVITY
Note Taking Guide Periodic Table1 of 7