HONORS CHEMISTRY
September 18-19, 2013
How do we know what the filling order is? What chemistry tool might we rely on?
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Electron Configurations and the Periodic TableElectron Configurations and the Periodic Table
Valence electron configurations repeat down a group
aufbau.exe.lnk
Ground state electron configurations
Example: Liatomic number = 3nucleus has 3 protonsneutral atom has 3 electrons
2 electrons in 1s orbital, 1 electron in 2s orbital
1s
2s
Different ways to show electron configuration
Read this “one s two”not “one s squared”
1s
2s
1s 2s
Li 1s2 2s1
Energy level diagram Box notation
Spectroscopic notation
Write the superscript 1.Don’t leave it blank
Using the Periodic Table
The last subshell in the electron configuration is one of these(row #) s (row # – 1) d(row #) p (row # – 2) f
The f-block is inserted into to the d-block
Electron configuration of O Atomic number of O = 8 so neutral atom has 8 e–
Electron configuration of Co Atomic number of Co = 27 so neutral atom has 27 e–
Simplifying electron configurationsShorthand Noble Gas Configuration
Build on the atom’s noble gas core
He 1s2
O 1s22s22p4
O [He]2s22p4
Ar 1s22s22p63s23p6
Co 1s22s22p63s23p64s23d7
Co [Ar]4s23d7
1s 2s 2p
3s 3p
4s 3d
1s 2s 2p
Noble Gases
Far right of the periodic table These elements are extremely unreactive
or inert They rarely form compounds with other
elements
Noble Gas electron configurations
What is the electron configurations for Neon
Abbreviated way to write configurationsStart with full outer shell then add on
Br Ba
Noble Gases
Neon- emits brilliant light when stimulated by electricity – neon signs- 4th most abundant element in the universe.
Helium- light non reactive gas- used balloons- inexpensive, plentiful and harmless
Radon- radioactive gas- can cause cancer- colorless, odorless emitted from for certain rocks underground
Properties of atoms correlate with the number and energy of electrons
Electron configurations are used to summarize the distribution of electrons among the various orbitals
Why are we doing all of this?Why are we doing all of this?
Electron configuration of ions
What is an ion? How many electrons does Cl1- have?
What is the electron configuration for the chloride ion?
How many electrons does Ca2+ have?What is the electron configuration for the calcium
ion? What do you notice?
Why is this important
Valence electrons Electrons in the outermost energy level
Where all the action occurs
The f-block is inserted into to the d-block
Find the electron configuration of Au Locate Au on the periodic table
Find the electron configuration of Au Au [Xe] The noble gas core is Xe
Find the electron configuration of Au Au [Xe]6s2
The noble gas core is Xe From Xe, go 2 spaces across the s-block in the 6th row
6s2
Find the electron configuration of Au Au [Xe]6s24f14
The noble gas core is Xe From Xe, go 2 spaces across the s-block in the 6th row
6s2
Then detour to go 14 spaces across the f-block 4f14
note: for the f-block, n = row – 2 = 6 – 2 = 4
Find the electron configuration of Au Au [Xe]6s24f145d9
The noble gas core is Xe From Xe, go 2 spaces across the s-block in the 6th row 6s2
Then detour to go 14 spaces across the f-block 4f14
note: for the f-block, n = row – 2 = 6 – 2 = 4 Finally go 9 spaces into the d-block on the 6th row 5d9
note: for the d-block, n = row – 1 = 6 – 1 = 5
Practice
Draw the orbital diagram for sulfur.What ion does sulfur want to form and why?
Draw the orbital diagram for Potassium.What ion does sulfur want to form and why?
What does this mean
Properties of atoms correlate with the number and energy of electrons
Atoms like to have full outer shells.
Refer to Atomic Structure Worksheet
Periodic Trends
Preview 4 Periodic Trends
Atomic Size/Radius Ionic Size (**)
Ionization EnergyElectronegativity
2 main factors affect periodic trendsNumber of electron shells (group)Effective Core Charge (ECC) (period)
Term (Refer to Definition Sheet) Effective Core Charge (ECC) 1) The net charge that pulls on the valence electrons in an
atom. The greater the effective core charge, the greater the pull. It is determined by subtracting the number of core electrons from the number of protons in the nucleus For example: Magnesium (label ECC on P.T.)
Term
Electron ShellPattern across the period?Pattern down the group?
Periodic Trends
Atomic radius The distance from the center of an atoms nucleus to it’s outermost electron
Measure of atomic size
Periodic Trends Graph the first 20 elements. What is the trend down a group? Across a Period?
Atomic radius
Periodic Trends
Atomic Radius Group Trend
Increases from top to bottom More energy levels or quantum levels (or “shell”) as
you go down a group – atomic radius increases Period Trend
Increases from right to left All electrons in the same energy level. Increased # of
protons holds them closer to nucleus. Decrease in Effective Core (Nuclear) Charge (ECC)
Calculate ECC for elements in period 2
Table of Table of Atomic Atomic RadiiRadii
Period Period Trend:Trend:Atomic Atomic RadiusRadius
Periodic Trends
Ionic Size
Size of an atom when electrons are added or removed.
Electrons removed atom becomes smaller.
Electrons added atoms become larger
Why? Electron-Electron
Repulsion
Ionic SizeIonic Size
CationsCations
Positively charged ions formed when an atom of a metal loses one or more electrons Smaller than the corresponding atom
AnionsAnions
Negatively charged ions formed when nonmetallic atoms gain one or more electrons
Larger than the corresponding atom
Periodic TrendsGraph the first 20 elements. What is the trend down a group? Across a Period? Ionic Size (label P.T.)
Table of Table of Ion Ion SizesSizes
Ionic Size
Group Trend Increases from top to bottom More energy levels as you go down a group – ionic
size increases Period Trend
Decreases as atoms lose more electrons Increases dramatically as atoms start gaining
electrons, decreases as atoms gain fewer electrons.
Periodic Trends
Ionization Energy Energy needed to remove one of the electrons on an atom’s outer shell.
How strongly does an atom hold it’s outermost electron.
Periodic Trends Graph the first 20 elements. What is the trend down a group? Across a Period?
Ionization Energy
Ionization Energy Group Trends
Increases from bottom to top.The closer outer shell electrons are to the
nucleus the harder they are to remove. Period Trend
Increases from left to right.The more electrons in the outer shell the harder
it is to remove one. Increase in Effective Core Charge (ECC)
Periodic Trend:Periodic Trend:Ionization Ionization EnergyEnergy
Periodic Trends
Electronegativity Is a measure of the level of attraction (pull) an atom exerts on the electrons of another atom.
Ability of an atom to attract electrons
Which elements want to gain electrons the most?
Periodic TrendsGraph the first 20 elements. What is the trend down a group? Across a Period? Electronegativity
Periodic Table of ElectronegativitiesPeriodic Table of Electronegativities
Electronegativity Group Trend
Increases from bottom to topAs radius decreases, electrons are closer to the
nucleus (decrease in number of electron shells) Period Trend
Increases from left to rightThe more electrons in the outer shell (up to 7)
the more the atom wants to attract electrons Exception: Trend does not apply to Noble Gases
Increase in Effective Core Charge (ECC)
Periodic Trend:Periodic Trend:ElectronegativityElectronegativity
Summarize the Trends
Questions???
Summary of Summary of Periodic TrendsPeriodic Trends
Practice
1. Se and Br1. Smallest atom
2. Lowest Ionization Energy
2. P, S, Se1. Largest atom
2. Highest Ionization Energy
3. Cl, Cl1-, Br, Br1-
1. Largest ionic size
4. Mg, Mg2+, Na, Na1+
1. Smallest ionic size
Atomic Properties DefinitionsFor Quiz – Monday Effective Core Charge:
It is the net charge that pulls on the valence electrons in an atom.
The greater the effective core charge, the greater the pull.
It is determined by subtracting the number of core electrons from the number of protons in the nucleus
Valence Electrons Are found in the outermost, valence, electron shell
(Bohr model) of the atom Core electrons
occupy all of the inner electron, core, shells
Atomic Properties Definitions Ionization Energy:
Energy needed to remove an electron from an atom or molecule. The higher the effective core charge and lower the number of
electrons shells, the greater the ionization energy Atomic size
How big (e.g., radius) an atom is Atomic radius is measured from the center of the nucleus to the
valence electron shell. The higher the effective core charge and lower the number of
electron shells, the smaller the atom. Electronegativity
Measure of the level of attraction (pull) an atom exerts on the electrons of another atom.
The higher the effective core charge and lower the number of electron shells, the greater the electronegativity
Homework
Atomic Structure Worksheet 5-3 Worksheet Study for Definition Quiz on Monday
Periodic TableObjective: Students know how to use the periodic table to identify alkali metals, alkaline earth metals, transition metals, metals, semimetals (metalloids), nonmetals, halogens and noble gases.
The Periodic TableThe Periodic Table
Dmitri Mendeleev – credited for the first periodic table in 1869. He had put element names and a few of their
properties on cards and then arranged them in various ways to help his students learn them more easily.
Arranged them so elements in the same column have similar properties.
Reactivity: Metal/NonMetal Trends
ELEMENT CLASSESELEMENT CLASSES
Periodic Song: http://www.privatehand.com/flash/elements.htmlPeriodic Song: http://www.privatehand.com/flash/elements.html
Reading the periodic table
Groups or families – vertical columns
Periods – horizontal rows
Alkali Metals All alkali metals have 1
valence electron They are very reactive Reactivity of these elements
increases down the groupAlkali metals:
http://video.google.com/videoplay?docid=-2134266654801392897#
Potassium, K reacts with water and must be stored in kerosene
Alkaline Earth Metals All alkaline earth metals have 2 valence
electrons Alkaline earth metals are less reactive than
alkali metals The word “alkaline” means “basic”
common bases include salts of the metals Ca(OH)2
Mg(OH)2
Properties of MetalsProperties of Metals Metals are good conductors of heat and electricity
Metals are malleable
Metals are ductile
Metals have high tensile strength
Metals have luster
Transition Transition MetalsMetals
Copper, Cu, is a relatively soft metal, and a very good electrical conductor.
Mercury, Hg, is the only metal that exists as a liquid at room temperature
Properties of Metalloids They have properties of both metals and nonmetals.Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster
Silicon, Si – A MetalloidSilicon, Si – A Metalloid Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity
Other metalloids include:
Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te
NonmetalsNonmetals Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature
Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
Examples of NonmetalsExamples of Nonmetals
Sulfur, S, was once known as “brimstone”
Microspheres of phosphorus, P, a reactive nonmetal
Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure
HalogensHalogens Halogens all have 7 valence electrons
Halogens in their pure form are diatomic molecules (F2, Cl2, Br2, and I2)
Chlorine is a yellow-green poisonous gas
Noble GasesNoble Gases
Noble gases have 8 valence electrons (except helium, which has only 2)
•they are chemically unreactive
• Colorless, odorless and unreactive; they were among the last of the natural elements to be discovered
Questions?
White Board
Refer to Periodic Trends Review
Electron Configurations and Periodic Trends Write the electron configuration and draw
an orbital diagram for each element Order each group of elements or ions
based on given data for each property requested on card
Use the orbital diagrams to explain the pattern. (does it agree with the “trend”)
Objectives
Use the periodic table to write electron configurations
Use the periodic table to obtain information about the properties of elements
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