6.1 PERIODIC TABLE

MEYER & MENDELEEV (1869): Showed connection between atomic mass & properties. Mendeleev – given credit (published first). Arranged by atomic mass. Found that properties repeated. Predicted existence & properties of undiscovered elements. (Ex. Ge) Recognized discrepancies in properties. (Ex. Te & I)

EARLY PERIODIC TABLE

MOSELY (1913) – Discovered protons (Atomic #) Arranged elements by atomic #. Saw clear pattern of periodic properties (problem of discrepancies solved). Periodic Law – When elements are arranged by increasing atomic number, there is a periodic repetition of chemical & physical properties.

MODERN PERIODIC TABLE: Boxes arranged by increasing atomic # Groups (families)– vertical columns. Numbered by “a” & “b” or 1-18 Elements in the same group share similar properties (Ex. Na & K – both in 1a) Representative elements (Main Group) Belong to “a” groups (“s” & “p” block) Wide range properties

PERIODS - Horizontal Rows Show # Energy Levels 7 periods on table Various properties Ex. Period 3 contains Na, Si, Cl, Ar (has 3 energy levels)

QUIZ 1) Mendeleev arranged elements by increasing ______. 2) How are elements arranged on the modern periodic table? 3) Sodium and magnesium are in the same _____. 4) Li & Na are in the same _____. 5) Which 2 elements have the most similar properties? Na Mg K Ar

ELEMENT CLASSIFICATION – 3 main types: Metals, Nonmetals, Metalloids Separated by “zigzag” line Metals: (Left of zigzag) (except H) Properties: Shiny & smooth (when clean) Ductile (can draw into wire) Malleable (hammer into sheets) Good conductors (heat & electricity) Often react with acids

GROUPS OF METALS 1a (1) = alkali metals (red) (not H) Most reactive metals (Fr most active) 2a (2) = alkaline earth metals (green) Very reactive

TRANSITION ELEMENTS (Metals) “d” block; “b” groups or # 3-12 Ex. Au, Fe, Cu Many transition metal compounds are colorful:

INNER TRANSITION ELEMENTS (Metals) ”f” block, 2 bottom rows (blue) 1st row (Lanthanide series) (Lanthanoid) 2nd row (Actinide series) (Actinoid)

QUIZ - METALS WHAT GROUP IS THIS? 1) Group 1a (1) 2) Group 2a (2) 3) Cu & Ag are in this group. 4) Bottom 2 rows are in this group. 5) Uranium is in this series. 6) Sm & Ce are in this series. 7) Most reactive metallic group. 8) Representative elements

NONMETALS – Right of zigzag & H Day 2 Properties: Gases or brittle & dull solids Only liquid is Br Poor conductors chlorine gas Groups: 6a (16) = chalcogens (oxygen gp.) 7a = halogens (very reactive) 8a = noble gases (inert, unreactive, full outer shell)

NONMETALS - What group is this? 1) Group 6a (16) 2) Group 7a (17) 3) Group 8a (18) 4) Hydrogen is the only nonmetal placed with this group. 5) The most reactive nonmetal group.

METALLOIDS (SEMI-METALS) Elements along zigzag (not Al) Show properties of both metals & nonmetals Ex. Si & Ge – shiny, semi-conductor, brittle Used in computer chips, etc.

OTHER GROUPS NAMED FOR 1st ELEMENT: Group 3a (13) Boron group Group 4a (14) Carbon group Group 5a (15) Nitrogen group Groups contain metals, nonmetals & metalloids.

QUIZ – METAL, NONMETAL, METALLOID 1) Tell whether the following is a metal, nonmetal or metalloid? Sr Co P Sb Se m m nm ml nm 2) An element is smooth, shiny, conducts electricity well, & reacts with acid. Which element is it? W Br As Ge W=metal

PROBLEM: Which element is this? 1) An element is a dull solid, brittle, and does not conduct electricity or react with acid. Which element & gp.? Mg Ge S O S, chalcogens 2) An element is shiny, brittle, partly conducts electricity but does not react with acid. Zn Ge Kr I Ge, Group 4A (carbon gp.)

Dmitri Mendeleev 1834-1907

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