unit 3 periodic table and valence electrons. valence electrons valence electrons are electrons...
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Valence electronsValence electrons
Valence electrons are electrons Valence electrons are electrons located in the outermost energy located in the outermost energy level.level.
They are located only in the They are located only in the s and p s and p sublevelssublevels
These electrons are involved in These electrons are involved in chemical bonding.chemical bonding.
Electron ConfigurationsElectron Configurations
An element’s electron configuration An element’s electron configuration shows how many valence electrons it shows how many valence electrons it has.has.
Example:Example:
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p44
Valence electrons = 6
PracticePractice
How many valence electrons do the How many valence electrons do the following elements have?following elements have?
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p66
1s1s222s2s222p2p663s3s223p3p22
1s1s222s2s22
8 valence electrons
4 Valence Electrons
2 valence electrons
Octet RuleOctet Rule Most elements want to have 8 valence Most elements want to have 8 valence
electrons (exception He)electrons (exception He)
Elements will gain or lose electrons in Elements will gain or lose electrons in their valence shell in order to achieve an their valence shell in order to achieve an octet.octet.– This process forms This process forms IonsIons..
Ions have the same electron Ions have the same electron configuration as their nearest configuration as their nearest noble gasnoble gas..
Positive IonsPositive Ions
Elements with less than 4 valence Elements with less than 4 valence electrons lose their outermost “s” electrons lose their outermost “s” and “p” sublevel electrons and “p” sublevel electrons
ExampleExample
Be: 1sBe: 1s222s2s2 2 has 2 valence electrons has 2 valence electrons
BeBe2+2+: 1s: 1s22 notice the ion has the samenotice the ion has the same
configuration as Heconfiguration as He– They always form positive ions.They always form positive ions.
Negative IonsNegative Ions
Elements with more than 4 valence Elements with more than 4 valence electrons gain electrons in their electrons gain electrons in their outermost “p” subleveloutermost “p” sublevel
ExampleExample
O: 1sO: 1s222s2s222p2p44 has 6 valence electronshas 6 valence electrons
OO2-2-: 1s: 1s222s2s222p2p66 now has 8 valencenow has 8 valence
electrons just like Neelectrons just like Ne– They always form negative ions.They always form negative ions.
Ion Formation SummaryIon Formation Summary Atoms gain or lose electrons to Atoms gain or lose electrons to
become more stable.become more stable.– They achieve the same electron They achieve the same electron
configuration as the Noble Gases.configuration as the Noble Gases.
Shorthand ConfigurationShorthand Configuration
S 16e-
Valence Electrons
Core Electrons
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
Noble Gas Shorthand Electron Noble Gas Shorthand Electron ConfigurationsConfigurations
Longhand ConfigurationLonghand Configuration
Noble Gas Shorthand Noble Gas Shorthand ConfigurationConfiguration
Shorthand ConfigurationShorthand Configuration– Core eCore e--:: Go up one row and over to the Go up one row and over to the
Noble Gas.Noble Gas.
– Valence eValence e--:: On the next row, fill in the On the next row, fill in the # of e# of e-- in each sublevel. in each sublevel.
[Ar] 4s2 3d10 4p2
Noble Gas Shorthand NotationNoble Gas Shorthand Notation Example - Example - GermaniumGermanium
Modern Periodic TableModern Periodic Table
Elements are arranged by increasing Elements are arranged by increasing atomic number.atomic number.– Recall that atomic number gives the Recall that atomic number gives the
number of protons in the nucleus of an number of protons in the nucleus of an atom.atom.
PeriodsPeriods
Horizontal rows on the periodic table Horizontal rows on the periodic table are called periods.are called periods.
Elements in the same period have Elements in the same period have the same number of valence shells.the same number of valence shells.
Elements in the same period share Elements in the same period share no similar chemical properties. no similar chemical properties.
Groups / FamiliesGroups / Families
Vertical columns on the periodic Vertical columns on the periodic Table are called groups.Table are called groups.
Groups are numbered 1-18Groups are numbered 1-18
Elements in the same group have the Elements in the same group have the same chemical properties because same chemical properties because they have the same number of they have the same number of valence electrons.valence electrons.
Some groups have special names.Some groups have special names.
Group 1 MetalsGroup 1 Metals
Known as Known as Alkali MetalsAlkali Metals Most active metals on periodic tableMost active metals on periodic table React violently with water, and React violently with water, and
become more active down the groupbecome more active down the group Only have 1 valence electron Only have 1 valence electron
(because they all end in s(because they all end in s11)) They all form ions with a +1 charge.They all form ions with a +1 charge.
Group 2 MetalsGroup 2 Metals Known as Known as Alkaline Earth MetalsAlkaline Earth Metals Also extremely reactive, but not as Also extremely reactive, but not as
much as Alkali Metalsmuch as Alkali Metals Contain 2 valence electrons (they end Contain 2 valence electrons (they end
in sin s22)) They all form ions with a +2 charge.They all form ions with a +2 charge.
Groups 3-12Groups 3-12 These groups are known as These groups are known as
Transition MetalsTransition Metals Not very reactive metalsNot very reactive metals Generally have 2 valence electrons Generally have 2 valence electrons Some of their “d” orbital electrons Some of their “d” orbital electrons
jump around into “p” orbitals so jump around into “p” orbitals so many of these elements have more many of these elements have more than one possible positive charge.than one possible positive charge.
Form colorful ion solutions (bright Form colorful ion solutions (bright vibrant colors)vibrant colors)
Group 17Group 17 Known as Known as HalogensHalogens Extremely reactive nonmetals; reactivity Extremely reactive nonmetals; reactivity
increases up a group (Fluorine the most increases up a group (Fluorine the most active)active)
Have 7 valence electrons (eHave 7 valence electrons (e-- configuration configuration ends in sends in s22pp55))
Most of these elements are toxic in their Most of these elements are toxic in their natural statenatural state
Most are also diatomic in their natural state Most are also diatomic in their natural state (F(F22, Br, Br22, Cl, Cl22, I, I22))
They all form ions with a (-1) charge.They all form ions with a (-1) charge.
Group 18Group 18 Known as Known as Noble gasesNoble gases Unreactive nonmetalsUnreactive nonmetals All have 8 valence electronsAll have 8 valence electrons (e- configuration ends in s(e- configuration ends in s22pp66), ),
except Helium (which has 2 except Helium (which has 2 electrons)electrons)
They do not form ions.They do not form ions.