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