Chapter 5 : The Periodic Table. Objectives Be able to define and explain each periodic trend,...
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Transcript of Chapter 5 : The Periodic Table. Objectives Be able to define and explain each periodic trend,...
Chapter 5 : The Chapter 5 : The Periodic TablePeriodic Table
ObjectivesObjectives Be able to define and explain each Be able to define and explain each
periodic trend, including comparing periodic trend, including comparing two different elements. For example: two different elements. For example: which of the following elements has which of the following elements has the larger atomic radius?the larger atomic radius?
History of the Periodic Table History of the Periodic Table
In the 1700s In the 1700s scientists had scientists had identified only identified only 30 elements30 elements
In the 1800s In the 1800s there were 60there were 60
History of the Periodic Table History of the Periodic Table
Early 1800s Early 1800s Dobereiner grouped Dobereiner grouped elements into triads elements into triads by physical and by physical and chemical propertieschemical properties
Li, Na, KLi, Na, K
History of the Periodic Table History of the Periodic Table 1865 J.A.R. Newlands 1865 J.A.R. Newlands
discovered that when discovered that when elements were elements were arranged by atomic arranged by atomic mass, properties mass, properties repeated themselves repeated themselves every eighth element every eighth element
Called these octavesCalled these octaves
Mendeleev Mendeleev 1869 Dmitri Mendeleev 1869 Dmitri Mendeleev
produced the first periodic produced the first periodic table for his studentstable for his students
Left blanks where Left blanks where elements had yet to be elements had yet to be discovereddiscovered
Not strictly in order of Not strictly in order of atomic mass (Ar atomic mass (Ar K)K)
Properties of Germanium as Predicted by Mendeleev
Properties ofEkasilicon
Predictedin 1871
Atomic weightDensity
Specific heatMelting pointOxide formula
Oxide density
Chloride formula
bp of chloride
725.5 g/cm3
0.31 J/(°C · g)Very highRO2
4.7 g/cm3
RCl4
100°C
Properties ofGermanium
Predictedin 1871
Observed in1886
Atomic weightDensity
Specific heatMelting pointOxide formula
Oxide density
Chloride formula
bp of chloride
725.5 g/cm3
0.31 J/(°C · g)Very highRO2
4.7 g/cm3
RCl4
100°C
72.35.47 g/cm3
0.32 J/(°C · g)960°CGeO2
4.70 g/cm3
GeCl4
86°C
MoseleyMoseley In 1913 Moseley In 1913 Moseley
assigned elements assigned elements atomic numbers and atomic numbers and rearranged periodic tablerearranged periodic table
Periodic LawPeriodic Law – when – when arranged by increasing arranged by increasing atomic number elements atomic number elements show periodic trendsshow periodic trends
Table TermsTable Terms Groups or Families Groups or Families are the are the
columns on the periodic tablecolumns on the periodic table Periods Periods are the rows going across.are the rows going across.
Periodic PropertiesPeriodic Properties Depend on two main factors: the Depend on two main factors: the
number of protons and electrons, number of protons and electrons, and the way these subatomic and the way these subatomic particles interact with each other.particles interact with each other.
Draw a Bohr Model forDraw a Bohr Model for LithiumLithium PotassiumPotassium FluorineFluorine Make sure to indicate the number of Make sure to indicate the number of
protons in the centerprotons in the center Make sure levels are the same size Make sure levels are the same size
from atom to atom (rings for energy from atom to atom (rings for energy levels should be the same size)levels should be the same size)
LithiumLithium
PotassiumPotassium
FluorineFluorine
Atomic RadiusAtomic Radius Atomic radiusAtomic radius is the distance from the atom’s nucleus is the distance from the atom’s nucleus
to its outer edge.to its outer edge. Simply can be thought of as the size of an atomSimply can be thought of as the size of an atom Using the Bohr model, and thinking about the number, Using the Bohr model, and thinking about the number,
arrangement, and interaction of the protons and arrangement, and interaction of the protons and electrons, answer the following questions, and explain electrons, answer the following questions, and explain your answersyour answers
Which atom has a larger atomic radius: lithium or Which atom has a larger atomic radius: lithium or potassium?potassium?
Which atom has a larger atomic radius: lithium or Which atom has a larger atomic radius: lithium or fluorine?fluorine?
What is the atomic radius ____ from left to right on the What is the atomic radius ____ from left to right on the periodic table.periodic table.
What is the atomic radius ____ from top to bottom on the What is the atomic radius ____ from top to bottom on the periodic table.periodic table.
Atomic RadiusAtomic Radius Atoms get larger going down a group Atoms get larger going down a group
or familyor family– Principle energy level increases Principle energy level increases
moving downmoving down Atoms get smaller moving from left Atoms get smaller moving from left
to rightto right– In the same energy level, more In the same energy level, more
protons exert a stronger pull protons exert a stronger pull towards the nucleustowards the nucleus
Ionization EnergyIonization Energy Ionization energy Ionization energy is the energy needed to is the energy needed to
remove one electronremove one electron Na(Na(gg) -> Na) -> Na++((gg) + 1e) + 1e-- Remember that an ion is a atom with an Remember that an ion is a atom with an
overall charge of negative or positive overall charge of negative or positive (number of electrons changes)(number of electrons changes)
Metals are more likely to give up an Metals are more likely to give up an electron than nonmetals.electron than nonmetals.
The more difficult it is to remove an electron The more difficult it is to remove an electron the higher the ionization energy will be.the higher the ionization energy will be.
Ionization Ionization Using the Bohr models, and thinking about the Using the Bohr models, and thinking about the
number, arrangement, and interaction of the number, arrangement, and interaction of the protons and electrons, answer the following protons and electrons, answer the following questions, and explain your anwsers.questions, and explain your anwsers.
Which atom has a higher ionization energy: Which atom has a higher ionization energy: lithium or potassium?lithium or potassium?
Which atom has a higher ionization energy: Which atom has a higher ionization energy: lithium or fluorine?lithium or fluorine?
Ionization energy______ from left to right on the Ionization energy______ from left to right on the perioidic tableperioidic table
Ionication energy _______from top to bottom on Ionication energy _______from top to bottom on the periodic tablethe periodic table
Ionization EnergyIonization Energy Ionization energy Ionization energy is the energy needed to is the energy needed to
remove one electronremove one electron Na(Na(gg) -> Na) -> Na++((gg) + 1e) + 1e-- Metals are more likely to give up an electron Metals are more likely to give up an electron
than nonmetals.than nonmetals. IE decreases when moving down the groupIE decreases when moving down the group IE increases moving from left to right in a IE increases moving from left to right in a
periodperiod There are second and third IEs for the next There are second and third IEs for the next
electronselectrons
Electron AffinityElectron Affinity Electron affinity Electron affinity is the energy change is the energy change
that occurs when an atom gains an electronthat occurs when an atom gains an electron F(F(gg) + e) + e-- F F-- ( (gg) ) Most atoms give off energy when an Most atoms give off energy when an
electron is gained (negative)electron is gained (negative) Nonmetals have more of an electron Nonmetals have more of an electron
affinity than metalsaffinity than metals Atoms with greater affinity are more able to Atoms with greater affinity are more able to
gain valance electronsgain valance electrons
Electron AffinityElectron Affinity Using the Bohr models, and thinking about the Using the Bohr models, and thinking about the
number, arrangement, and interaction of the number, arrangement, and interaction of the protons and electrons, answer the following protons and electrons, answer the following questions, and explain your answers.questions, and explain your answers.
Which atom has a greater electron affinity: Which atom has a greater electron affinity: lithium or potassium?lithium or potassium?
Which atom has a greater electron affinity: Which atom has a greater electron affinity: lithium or fluorine?lithium or fluorine?
Electron affinity _______ from left to right on the Electron affinity _______ from left to right on the periodic table.periodic table.
Electron affinity ______from top to bottom on the Electron affinity ______from top to bottom on the periodic tableperiodic table
Electron affinityElectron affinity EA decreases when moving down EA decreases when moving down
the groupthe group EA increases moving from left to EA increases moving from left to
right in a periodright in a period
ElectronegativityElectronegativity Electronegativity Electronegativity reflects an atom’s ability to reflects an atom’s ability to
attract electronsattract electrons It is defined as the ability of an atom in a molecule to It is defined as the ability of an atom in a molecule to
attract electrons.attract electrons. Example: if a molecule consists of atoms X bonded to Example: if a molecule consists of atoms X bonded to
atom Y.atom Y. X-YX-Y The two atoms share the electrons in the molecule. The two atoms share the electrons in the molecule.
If X is more electronegative than Y, then the If X is more electronegative than Y, then the electrons will be more strongly attracted to X than Y, electrons will be more strongly attracted to X than Y, and will “hog” the electronsand will “hog” the electrons
X – YX – Y
ElectronegativityElectronegativity Which atom has a greater Which atom has a greater
electronegativity: lithium or potassium?electronegativity: lithium or potassium? Which atom has a greater Which atom has a greater
electronegativity: lithium or fluorine?electronegativity: lithium or fluorine? Electronegativity _______ from left to Electronegativity _______ from left to
right on the periodic table.right on the periodic table. Electronegativity______ from top to Electronegativity______ from top to
bottom on the periodic tablebottom on the periodic table
ElectronegativityElectronegativityCs & Fr have the lowest Cs & Fr have the lowest
electronegativities; F has the electronegativities; F has the highesthighest
EN decreases when moving EN decreases when moving down the groupdown the group
EN increases when moving from EN increases when moving from left to right across the periodleft to right across the period
Ionic RadiusIonic Radius Ionic radiusIonic radius is the distance from the ion’s is the distance from the ion’s
nucleus to its outer edge.nucleus to its outer edge. Remember that positive ions are formed Remember that positive ions are formed
when atoms lose electronswhen atoms lose electrons Negative ions are formed when atoms gain Negative ions are formed when atoms gain
electronselectrons Ions get larger going down a group or Ions get larger going down a group or
familyfamily Ions get larger moving from left to rightIons get larger moving from left to right
– The more electrons added increases repulsion The more electrons added increases repulsion among themamong them
Draw the Bohr models for the Draw the Bohr models for the following:following:
Lithium and Lithium ion (+)Lithium and Lithium ion (+) How does the lithium ion’s radius compare How does the lithium ion’s radius compare
to the radius of neutral lithium?to the radius of neutral lithium? Chlorine and Chlorine ion (-)Chlorine and Chlorine ion (-) How does the chloride ion’s radius How does the chloride ion’s radius
compare to the radius of neutral chlorine?compare to the radius of neutral chlorine? Sodium ion (+) and Fluoride Ion (-)Sodium ion (+) and Fluoride Ion (-) How do the number of electrons in these How do the number of electrons in these
two ions compare to each other?two ions compare to each other? How do the radii of these two ions How do the radii of these two ions
compare to each other?compare to each other?
Ionic radiusIonic radius Ions get larger going down a Ions get larger going down a
group or familygroup or family Ions get larger moving from Ions get larger moving from
left to rightleft to right– The more electrons added The more electrons added
increases repulsion among increases repulsion among themthem
Major Groups on the Periodic Major Groups on the Periodic TableTable
Alkali MetalsAlkali Metals Alkaline Earth Alkaline Earth
MetalsMetals Transition Metals Transition Metals Boron GroupBoron Group Carbon GroupCarbon Group Nitrogen GroupNitrogen Group
Oxygen Group Oxygen Group (Chalcogens)(Chalcogens)
HalogensHalogens Noble GasesNoble Gases Actinide SeriesActinide Series Lanthanide Lanthanide
SeriesSeries
Reactivity of Alkali and Alkaline Reactivity of Alkali and Alkaline Earth MetalsEarth Metals
Metals become Metals become more reactive as more reactive as you move down you move down the groupthe group
Metals become Metals become less active when less active when moving left to moving left to rightright
Why Are There Patterns?Why Are There Patterns? Elements have physical and chemical Elements have physical and chemical
properties based upon their valence properties based upon their valence electrons.electrons.
Valence electronsValence electrons are the electrons in are the electrons in the outer most energy level (s & p the outer most energy level (s & p orbitals)orbitals)
The number of valence electrons may The number of valence electrons may be determined by using the periodic be determined by using the periodic tabletable
Why Are There Patterns?Why Are There Patterns? When you look at an atom you are When you look at an atom you are
observing the valence electronsobserving the valence electrons Duet rule - only 2 electrons fill the Duet rule - only 2 electrons fill the
first energy levelfirst energy level Octet rule – 8 valence electrons is Octet rule – 8 valence electrons is
considered to be a full setconsidered to be a full set