Periodic Table

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• Periodic Table
• Origin of the Periodic Table starts with Dmitri
  Mendeleev and Lothar Meyer
• Both arranged the elements in order of atomic
  weight and placed elements with similar
  properties in columns.
• At the time only 63 or so elements were known and
  there were obvious missing elements in their
  periodic tables
• Mendeleev was able to predict fairly accurately
  the chemical and physical properties of some of
  these missing elements such as Ga and Ge
• Henry Moseley observed that the n of x-rays
  emitted by elements bombarded with electrons
  increased with atomic weight.
• He labeled the emissions using an integer he
  called the atomic number.
• The use of the atomic number improved the
  organization
• For some horizontal neighboring pairs, the
  element with the higher atomic number has a
  lower atomic weight.
• Compare Ar to K Co to Ni Te to I Th to Pa U
  to Np

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Periodic Table Periodic Law When the elements
are arranged in order of their atomic numbers,
there is a periodic, or cyclic, repetition in
their chemical and physical properties. Periods
are the rows of elements. They are numbered 1,
2, 3, Groups or Families of elements are
vertical columns. They are labeled with Roman or
Arabic numerals and letters Some groups have
common names IA or 1A - alkali metals IIA or
2A - alkaline earth metals VIA or 6A -
chalcogens VIIA or 7A - halogens VIII or 8A -
noble gases A elements - representative or main
group elements B elements - transition metals
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• Periodic Table
• Metals are along the left and middle of the
  periodic table
• Good electrical and thermal conductors
• Metallic luster
• Malleable and ductile
• Except for Hg, all are solids at room temperature
• Non-metals are in the upper right of the periodic
  table
• Non-conductors of electricity and heat
• Sometimes colored
• Gases, liquid and low melting solids
• Metalloids are on a diagonal separating the
  metals from the non-metals
• Intermediate properties - semiconductors,
  insulators

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• Periodic Table
• Group 1A - H and the Alkali metals Li, Na, K, Rb,
  Cs, Fr
• H normally exists a gaseous diatomic molecules,
  H2
• The other elements are metallic solids
• They are the most active metals and are always
  found combined in nature
• They are isolated by electrolysis 2NaCl(l )
  2Na(s) Cl2(g)
• They react with most non-metals
• 2M(s) H2(g) 2MH(s)
• 2M(s) S(s) M2S(s)
• 2M(s) Cl2 (g) 2MCl(s)
• They react with H2O(l ) with sufficient release
  of heat to cause ignition of the H2 produced
• 2M (s) 2H2O(l ) H2(g) 2MOH(aq)
• Li reacts with O2(g) to form lithium oxide
  4Li(s) O2 (g) 2Li2O(s)
• Na reacts with O2(g) to form sodium peroxide
  2Na(s) O2 (g) Na2O2(s)
• K, Rb, Cs react with O2(g) to give metal
  superoxide M(s) O2(g) MO2(s)
• ? reacts with O2 to give water 2H2(g) O2(g)
  2H2O(l )

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• Periodic Table
• Group 2A - Alkaline Earth Metals Be, Mg, Ca, Sr,
  Ba, Ra
• Some physical properties
• Densities are low but higher than alkali metals
• Melting temperatures are much higher than alkali
  metals
• Their chemical activity increases with atomic
  mass
• Be does not react with water or steam even at red
  heat
• Mg does not react with water but will react with
  steam
• Mg(s) H2O(g) MgO(s) H2(g)
• Ca, Sr, Ba react with water at room temperature
• Ca(s) 2H2O(l ) Ca(OH)2(aq) H2(g)
• The reaction with oxygen gives MO 2 Mg(s)
  O2(g) MgO
• Transition elements are all metals
• Except for Cu, Pt and Au, all are found combined
  with other elements in nature
• Have many commercial uses Fe, V, Cr, Mn, Ni in
  steel
• Au, Ag, Cu in jewlery, electronics and electrical
  industries
• Some are biologically important Fe in hemoglobin
  and cytochromes

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• Periodic Table
• Group 3A - B, Al, Ga, In, Tl
• B is a metalloid
• Al, Ga, In, Tl are metals
• Boron is found in borax, Na2B4O710H2O
• NaBH4 is a fairly important chemical for organic
  chemistry
• Aluminum is the most abundant metal in the
  earths crust
• Group 4A - C, Si, Ge, Sn, Pb
• C is nonmetallic Si, Ge are metalloids Sn, Pb
  are metals
• C has at least three allotropes different forms
  of an element that exist in the same physical
  state under the same conditions of temperature
  and pressure

graphite
diamond
buckyballs (C60)
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• Periodic Table
• Group 4A - C, Si, Ge, Sn, Pb
• Graphite exists as flat sheets of molecules with
  fused 6-membered rings carbon of carbon atoms
  which can slip passed one another
• Sheets of graphite can be formed into extremely
  strong fibers for use in golf clubs, jet
  fighters and bombers, sail boat masts and tennis
  rackets
• Diamond is the hardest substance known to man and
  is used as an abrasive for polishing and cutting
• The structure of diamond is a lattice work in
  which each C atom is bonded to 4 other C atoms
• Diamond is an excellent conductor of heat but an
  electrical insulator and can be synthetically
  formed into thin sheets for use in semiconductor
  devices
• Si is found in nature as SiO2 in quartz and sand
• Pure Si has the same structure as diamond
• Major uses of Si and its compounds include
  concrete production, semiconductor devices,
  glass, fiber optic devices
• Sn is used as solder and mixed with copper to
  make bronze
• Pb is used for electrical solder as a mixture
  with Sn
• A major use of Pb is in lead acid batteries

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• Periodic Table
• Group 5A - N, P, As, Sb, Bi
• N2 makes up 75 of the atmosphere
• It is a constituent element of proteins,
  important biochemical compounds
• Phosphorus - meaning light-bearing - is found in
  bones and teeth
• White and red phosphorus are two allotropes of
  phosphorus
• As H3PO4, it is found in most softdrinks, and
  Na3PO4 is used as a cleaner

• As and Sb are metalloids
• Bi is a metal and is the heaviest element that is
  not radioactive
• All group 5A elements make oxides with general
  formula E2O3 and sulfides with general formula
  E2S3.

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• Periodic Table
• Group 6A - Chalcogens O, S, Se, Te, Po
• O, S, Se are nonmetals, Po is a radioactive metal
• O2(g) and O3(g) are two allotropes of oxygen
• O3(g) is a pungent smelling, poisonous gas, that
  can be formed in an electric discharge 3O2(g)
  O2(g)
• O2 is a very good oxidizing agent(! )because it
  attracts electrons strongly from other metal
  and non-metal elements.
• Compounds of O22- and O2- slowly decompose
• 2H2O2(aq) 2H2O(l ) O2(g)
• Sulfur exists as S8 molecules in its most stable
  form.
• S readily forms S2- ions because it attracts
  electrons from other elements
• S also reacts with other elements including
  oxygen S(s) O2(g) SO2(g)

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• Periodic Table
• Group 7A - Halogens - salt formers F, Cl, Br, I,
  At
• All halogens are non-metal, diatomic molecules
• Much of the chemistry of the halogens involves X-
  ions.
• F2 is the best oxidizing agents of all the
  elements and reacts vigorously with almost every
  other substance
• 2H2O(l ) 2F2(g) 4HF(aq) O2(g)
• Cl2 can be produced from electrolysis of molten
  NaCl or brine
• 2NaCl(aq) 2H2O(l ) 2NaOH(aq) Cl2(g)
  H2(g)
• Cl2 is added to water (where its converted to
  HOCl) as a disinfectant
• Cl2(g) H2O(l ) HOCl(aq) HCl(aq)
• (NaOCl is chlorine bleach, Chlorox)

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• Periodic Table
• Group 8A - Noble gases He, Ne, Ar, Xe, Rn
• Exist as monatomic gases
• These elements are not chemically very active.
• Only a few compounds with F or F and O are known
  for Xe and KrF2

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• Molecules and Molecular Compounds
• A molecule is an assembly of two or more atoms
  tightly bound together.
• When the atoms of 2 or more elements are in a
  molecule, this is the smallest particle of such
  a compound.
• Some elements exist as molecules
• O2 oxygen sometimes called dioxygen,
• O3 ozone
• H2 hydrogen sometimes called dihydrogen
• N2 nitrogen sometimes called dinitrogen
• Halogens F2, Cl2, Br2 I2
• S8 sulfur, P4 phosphorus,
• Many compounds are molecular
• HCl, H2O, H2O2, CH4, CO, CO2, C2H4,
• Molecules with two atoms are diatomic

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• Chemical Formulas
• A chemical formula is representation of a
  molecule of a molecular compound
• Molecular Formulas give the actual number of
  atoms of each element in a molecule
• O2, CO2, CO, H2O, H2O2, C6H6
• Empirical Formulas give the smallest whole number
  ratio of the atoms of each element in a molecule
• For C6H6, its empirical formula is CH
• For H2O2, its empirical formula is HO
• Different compounds may have the same empirical
  formula
• 
  (structural formulas)
• Molecular Formula CH2O C2H4O2
• Empirical Formula CH2O CH2O

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Representations of Molecules structural
perspective ball-and-stick
space filling formula
drawing Molecular Models allow one to visualize
molecules in three space
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• Ions and Ionic Compounds
• Ions are atoms or molecules that have gained or
  lost electrons to become charged species.
• Atoms of Metal Elements lose electrons to become
  positively charged ions. Positive ions are
  called cations.
• Atoms of Non-metal Elements gain electrons to
  become negatively charged ions. Negative ions
  are called anions.

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• Ions and Ionic Compounds
• Polyatomic ions are molecular species that have
  gained or lost electrons
• NO3-, SO42-, PO43- (nitrate ion, sulfate ion,
  phosphate ion)
• NH4, H3O (ammonium ion, hydronium ion)
• Predicting Ionic Charges
• Metal Representative Elements
• Group 1A elements lose 1e, and thus have the same
  of electrons as the previous Noble Gas.
• Na has 11 electrons Na has 10 electrons Ne has
  10 electrons
• Group 2A elements lose 2es and thus have the
  same of electrons as the previous Noble Gas.
• Ca has 20 electrons Ca2 has 18 electrons Ar
  has 18 electrons

Learn the formulas, names and charges of the
polyatomic ions in Table 3.1, p 110 in Kotz
Treichel
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• Predicting Ionic Charges
• Non-metal Representative Elements
• Non-metal representative elements gain enough
  electrons to have the same number of electrons
  as the next Noble Gas element.
• F has 9 electrons F- has 10 electrons Ne has 10
  electrons
• O has 8 electrons O2- has 10 electrons Ne has
  10 electrons
• N has 7 electrons N3- has 10 electrons Ne has
  10 electrons
• Each transition element may have ions with more
  than one charge

Learn the formulas, names and charges of the ions
in Figure 3.6, p. 107 in Kotz Treichel
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