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12.1 Section A and B, 12.1 Section A and B, 12.212.2
Group 1Group 1
Period 6Period 6
BondsBonds
Bond – a force that holds together Bond – a force that holds together two or more atoms and functions as two or more atoms and functions as one unitone unit
Bond energy – the strength required Bond energy – the strength required to break the bondto break the bond
Bonds
ExampleExample
What’s the difference between bond What’s the difference between bond and bond energy?and bond energy?
AnswerAnswer
Bonds hold together atoms while Bonds hold together atoms while bond energy is a characteristic of a bond energy is a characteristic of a bond in which it describes how bond in which it describes how strong a bond is.strong a bond is.
Types of Chemical BondsTypes of Chemical Bonds
Covalent bond – a bond that forms Covalent bond – a bond that forms when two nonmetals reactwhen two nonmetals react
Ionic bond – a bond that forms when Ionic bond – a bond that forms when a nonmetal and a metal reacta nonmetal and a metal react
Polar Covalent bond – between two Polar Covalent bond – between two extremes in which atoms are not that extremes in which atoms are not that different so that there is an unequal different so that there is an unequal sharing of electronssharing of electrons
Methane (covalent bond)
ExampleExample
What happens to the electrons in a What happens to the electrons in a covalent bond?covalent bond?
AnswerAnswer
The electrons are shared by each of The electrons are shared by each of the atoms.the atoms.
ElectronegativityElectronegativity
Electronegativity – the ability for an Electronegativity – the ability for an atom to attract electronsatom to attract electrons
Electronegativity increases up a Electronegativity increases up a group and across a periodgroup and across a period
Similar electronegativity results in a Similar electronegativity results in a covalent bond and different covalent bond and different electronegativity results in an ionic electronegativity results in an ionic bondbond
Electronegativity ranges from 0-4.0Electronegativity ranges from 0-4.0
Electronegativity
ExampleExample
On the periodic table, how does On the periodic table, how does electronegativity increase and electronegativity increase and decrease?decrease?
AnswerAnswer
Electronegativity increases going up Electronegativity increases going up a group and across a period(left to a group and across a period(left to right). It decreases going down a right). It decreases going down a group and across a period (right to group and across a period (right to left).left).
Electron ConfigurationsElectron Configurations
Groups 1 and 2 are the Groups 1 and 2 are the ss orbitals – two orbitals – two electrons max in eachelectrons max in each
Groups 3-12 are the Groups 3-12 are the dd orbitals – 10 orbitals – 10 electrons maxelectrons max
Groups 13-18 are the Groups 13-18 are the pp orbitals – 6 orbitals – 6 electrons maxelectrons max
Lanthanides – bottom of the periodic table Lanthanides – bottom of the periodic table – have – have ff orbitals and hold 15 electrons orbitals and hold 15 electrons
You read across the table to do electron You read across the table to do electron configurationsconfigurations
Electron Configuration
ExampleExample
Write the electron configuration for Write the electron configuration for Ca. Tell what noble gas you would Ca. Tell what noble gas you would use to abbreviate.use to abbreviate.
AnswerAnswer
1s^2 2s^2 2p^6 3s^2 3p^6 4s^21s^2 2s^2 2p^6 3s^2 3p^6 4s^2 You would use ArgonYou would use Argon
Structures of Ionic CompoundsStructures of Ionic Compounds When a nonmetal and a metal react they usually When a nonmetal and a metal react they usually
form an octet (8 valence electrons)form an octet (8 valence electrons) Stable compounds achieve an octetStable compounds achieve an octet Cation is always smaller than the atom and the Cation is always smaller than the atom and the
anion is always bigger than the atomanion is always bigger than the atom Cations are the metals and the anions are the Cations are the metals and the anions are the
nonmetalsnonmetals Anions are bigger because they are greedy for Anions are bigger because they are greedy for
electrons while the cation are smaller because electrons while the cation are smaller because they have to give up electronsthey have to give up electrons
Polyatomic ions are held together by covalent Polyatomic ions are held together by covalent bondsbonds
Sodium Chloride Crystal Lattice
ExampleExample
When a metal and a nonmetal react, When a metal and a nonmetal react, in what conditions are they stable?in what conditions are they stable?
AnswerAnswer
When they form an octet they are When they form an octet they are stable because they have achieved a stable because they have achieved a noble gas electron configuration.noble gas electron configuration.
QuizQuiz
1)1) What are cations? Anions?What are cations? Anions?2)2) What happens when a metal loses What happens when a metal loses
all of its valence electronsall of its valence electrons3)3) What are the individual polyatomic What are the individual polyatomic
ions held together by?ions held together by?4)4) What is larger the anion or the What is larger the anion or the
cation?cation?5)5) What is the range of What is the range of
electronegativity?electronegativity?
AnswersAnswers
1)1) Cations are the metals and the anions Cations are the metals and the anions are the nonmetals.are the nonmetals.
2)2) It gets smaller because it loses its It gets smaller because it loses its electrons.electrons.
3)3) Covalent bonds.Covalent bonds.
4)4) The anions are always bigger because The anions are always bigger because they gain electrons from the metals.they gain electrons from the metals.
5)5) The lowest electronegativity is 0 and the The lowest electronegativity is 0 and the highest is 4.0.highest is 4.0.
ReferencesReferences
subtopic 1 subtopic 1 http://www.vias.org/feee/img/00257.pnghttp://www.vias.org/feee/img/00257.png subtopic 2subtopic 2 http://www.windows.ucar.edu/physical_science/chemistry/chttp://www.windows.ucar.edu/physical_science/chemistry/ch4_molecule_big.gifh4_molecule_big.gif subtopic 3subtopic 3 http://www.chem.fsu.edu/chemlab/chm1050lmanual/halogehttp://www.chem.fsu.edu/chemlab/chm1050lmanual/halogens/polar_bond.jpgns/polar_bond.jpg subtopic 4subtopic 4 http://www.mpcfaculty.net/mark_bishop/periodic_table_blochttp://www.mpcfaculty.net/mark_bishop/periodic_table_blocks_alone.jpgks_alone.jpg subtopic 5subtopic 5 http://www4.nau.edu/meteorite/Meteorite/Images/Sodium_chttp://www4.nau.edu/meteorite/Meteorite/Images/Sodium_chloride_crystal.pnghloride_crystal.png