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What is the periodic table?

• compact way of organizing elements• contains a lot of information • allows us to make predictions about

behavior and properties of elements

• Elements

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History of the Periodic Table

• End of the 1700’s – less than 30 elements known

• Many elements discovered during 1800’s

• Many experiments done to determine atomic masses

John Newlands

• 1864: if elements arranged by atomic mass - properties repeat every 8th element

• Law of Octaves – did not work for all known elements

• Key idea was correct: Properties of elements do repeat in periodic way

Mendeleev & MeyerMendeleev produced 1st accepted PT: 1869•Elements ordered by ↑ atomic mass into columns with similar properties•PredictedPredicted existence & properties of undiscovered elements•Not totally correct

– more accurate atomic mass calculations showed some elements weren’t in right place

Remember

1860’s:

•No subatomic particles yet discovered

•Dalton’s billiard ball model of the atom

1913 – Henry Moseley

• by 1913, protons & electrons discovered– Neutrons were predicted

• Moseley determined atoms of each element contain unique # protons (= atomic number)

• rearranged Mendeleev’s PT by atomic number instead of mass

• problems with elements in wrong place disappeared

Periodic Law

• There is a periodic repetition of chemical and physical properties of elements when arranged by increasing atomic numberincreasing atomic number

Glenn Seaborg: 1950’s

• Lanthanide and Actinide Series

Seaborg

Mendeleev

Mosley

Newlands

Vocabulary of PT

• Columns called groupsgroups or familiesfamilies – Today: #1 thru 18, Arabic numerals– Past: A & B groups, Roman numerals

• A-Group – Columns 1,2,13-18 (= representative elements)– IA – 8A

• B-Group– Transition metals (columns 3-12)– IB - 8B

• Rows are called seriesseries or periodsperiods– #1 thru 7

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Column numbering (1 18) left to right

Period numbering (1 7) top to bottom

Structure of Periodic Table

• Closely related to electron configuration of each element

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Energy Levels = Row Number

• Elements in same row have same # of principal energy levels – so # of principal energy levels = to row #

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Going Across Row 2:Going Across Row 2:

2-8Ne18 (VIIIA)

2-7F17 (VIIA)

2-6O16 (VIA)

2-5N15 (VA)

2-4C14 (IVA)

2-3B13 (IIIA)

2-2Be2 (IIA)

2-1Li1 (IA)

ConfigurationElementFamily

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Going Down Column 1:Going Down Column 1:

2-8-18-32-18-8-1Fr7

2-8-18-18-8-1Cs6

2-8-18-8-1Rb5

2-8-8-1K4

2-8-1Na3

2-1Li2

1H1

ConfigurationElementPeriod

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Valence Electrons

414 or IVA

313 or IIIA

22 or IIA

11 or IA

Number of Valence Electrons

Group

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Valence Electrons

• Chemical behavior determined by # valence electrons

• Elements with same # valence electrons will have similar chemical properties– Elements in same column have similar

chemical properties

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Classifying the Elements

• 2/3 (75%) of elements are metalsmetals• Remaining elements: non-metalsnon-metals &

metalloidsmetalloids (semi-metals)• Metalloids:

– some properties of metals & some properties of nonmetals

• Staircase:Staircase: – dividing line between metals & nonmetals – elements to left are metals (except H)– elements to right are non-metals

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Properties of Metals

• Malleable – flattened into sheets

• Ductile – drawn into wires & tubes

• have Luster

• Good Conductors of heat & electricity

• Solid at room temperature (except Hg)

• Metals lose electrons & form positive ions “Metals are losers”“Metals are losers”

• Low ionization energy

• Low electronegativity

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Properties of Nonmetals• generally gases or solids (except Br2)• solids are Brittle• solids are Dull• poor conductors of heat & electricity• Nonmetals gain electrons & form negative ions “ “Nonmetals are winners”Nonmetals are winners”• High ionization energy• High electronegativity

Properties: OPPOSITE of metals

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Properties of Metalloids

7 metalloids: – 5 on right of staircase: B,Si,As,Te,At– 2 on left of staircase: Ge,Sb

Each metalloid has some metallic and some nonmetallic properties– Example:Si

• shiny like metal but brittle like nonmetal

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Names of Families(AKA group A elements)

• Group 1 = Alkali Metals

• Group 2 = Alkaline Earth Metals

• Groups 3-12: Transition metals

• Group 13 = Boron family

• Group 14 = Carbon family

• Group 15 = Nitrogen family

• Group 16 = Oxygen family

• Group 17 = Halogens

• Group 18 = Noble Gases

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Transition Metals

• Groups 3 through 12

• AKA group B elements

• Actinide & Lanthanide series – inner transition elements

• put the COLOR in your life– form brightly colored salts/solutions

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Elements that are gases at STP

Diatomics:

H2, N2, O2, F2, Cl2

Monatomics: noble gases He, Ne, Ar, Kr, Xe, Rn

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Two Elements: liquid at room temperature

Br2 (non-metal) and Hg (metal)

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All other elements are solids at room temperature