Chapter 6 Notes Manipulating Polyatomic Ions and Chemical Bonding

Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Chapter 6 Notes – Problem Set: page 209: 1, 2, 3, 4, 6, 13, 15, 19, 20, 21, 25, 27, 28, 33, 34, 37, 39, 41, 42, 45, 47, 48, 49

Rules for expanding your list of polyatomic ions

Polyatomic ions vary in their charges, number of oxygen atoms, and number of hydrogen atoms. All students of accelerated chemistry must memorize 10 polyatomic ions. Once these ions are memorized, you can learn new rules to expand the number of polyatomic ions that you can use in chemistry class. Please realize that it is very difficult to expand if you do not know the first 10 polyatomic ions. Please learn these 10!!

Basic Polyatomic Ions

Name Formula Name Formula Hydroxide Nitrate Ammonium Phosphate Acetate Chromate Carbonate Dichromate Sulfate Chlorate Ways of expanding your list of polyatomic ions:

1. To change the number of oxygens:

-1 One more oxygen ClO4 ______

-1 Memorized ClO3 ______

-1 One less oxygen ClO2 ______

Two less oxygens ClO-1 ______

2. Whatever is true for chlorine, is also true for fluorine, bromine, and iodine.

-1 F substitution FO3 ______

-1 Br substitution BrO3 ______

-1 I substitution IO3 ______

3. If you add a Hydrogen, you have to make the ion more positive and call the ion “bi______”

-2 -1 Memorized CO3 is carbonate, so HCO3 is ______

-2 -1 Memorized SO4 is sulfate, so HSO4 is ______

0bbbbff75f5c734da32b162fe62be90a.doc Page 1 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding 4. Combinations of #1, #2, and #3 are possible:

-1 -1 HSO3 is called bisulfite, FO2 is called ______

General Rules for expanding your list of polyatomic ions Know the basic polyatomic ions: Name Formula Name Formula -1 NO -1 Hydroxide OH Nitrate 3 +1 -3 Ammonium NH4 Phosphate PO4 -1 -2 Acetate C2H3O2 Chromate CrO4 -2 -2 Carbonate CO3 Dichromate Cr2O7 -2 -1 Sulfate SO4 Chlorate ClO3

Rule #1 Change the number of oxygens: Remove one oxygen = change ending of name to ______

Remove two oxygens = change ending of name to –ite and beginning of name to ______

Add one oxygen = change beginning of name to ______

Examples: Name Formula Name Formula Name Formula Name Formula -1 -2 -1 -3 ClO4 SO5 NO4 PO5 -1 -2 -1 -3 ClO3 SO4 NO3 PO4 -1 -2 -1 -3 ClO2 SO3 NO2 PO3 -1 -2 -1 -3 ClO SO2 NO PO2

Rule #2 Other family members: Elements near each other in the same column tend to form similar polyatomic ions.

Examples: Name Formula Name Formula Name Formula -1 Chlorate ClO3 Sulfate Phosphate Fluorate Selenate Arsenate Iodate Bromate

Rule #3 Add Hydrogen Add only one H = change the beginning of the name to ______and make the charge one less negative (due to hydrogen’s positive one charge)

Examples: Name Formula Name Formula -2 -2 Carbonate CO3 Sulfate SO4 Bicarbonate Bisulfate

0bbbbff75f5c734da32b162fe62be90a.doc Page 2 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Rule #4 Combine rules 1, 2, and 3

-1 EX 1. HSO3 -2 Memorized SO4 ______

-2 Lose an “O” SO3 ______

-1 Add an “H” HSO3 ______

EX 2. HFO2

-1 Substitute an F FO3 ______

-1 Lose an “O” FO2 ______

Add an “H” HFO2 ______

Ex3: What is the formula for hypoiodite?

Hypoiodite = ______

Ex4: What is the formula for Biperselenate?

Biperselenate = ______

Monatomic Ions 0bbbbff75f5c734da32b162fe62be90a.doc Page 3 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding

For nonmetals, almost all single names that end with –ide indicates a single charged atom.

Simply write the symbol and the charge. The periodic table column indirectly indicates the element’s charge. Remember, elements want to have 8 electrons in their outer shell (Octet Rule).

For example, column #1 elements have a +1 charge, column #2 elements have a +2 charge, column #3 = +3, column #5 = -3, column #6 = -2, and column #7 = -1.

Ex1: What is the formula for chloride?

Ex2: What is the formula for an aluminum ion?

Ex3: What is the name of the S-2 anion?

Ex4: What is the name of the Mg+2 cation?

0bbbbff75f5c734da32b162fe62be90a.doc Page 4 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding 6.1 Introduction to chemical bonding

Most elements are not found alone in nature. They are ______

Chemical Bond - ______.

Types of chemical bonds:

Ionic - ______

Covalent – ______

Metallic - ______

Covalent bonds may be polar or nonpolar

Polar - ______

Nonpolar - ______

There are two ways to predict polar vs. nonpolar ( and covalent vs. ionic)

#1 Use electronegativity difference

0 = nonpolar covalent 0.4 - 1.7 = polar covalent greater than 1.7 = ionic

Examples:

NaCl HCl Cl2

#2 - There is an easier way to predict

Ionic = ______or ______Polar Covalent = ______Nonpolar Covalent = ______

0bbbbff75f5c734da32b162fe62be90a.doc Page 5 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Ionic Bonding

- Ionic compound - a substance composed of positive and neg. ions so that the charges Are______. It involves a ______of electrons.

+2 –1 Ca with Cl will form the compound CaCl2. It takes ______chlorine ions to cancel out the the +2 charge on the calcium ion.

- Ionic Bond – - - Formula unit -

- Metals - lose electrons - why? ______

- Nonmetals - gain electrons - why? ______

- Metals lose electrons until they become like a ______(usually 8 valence electrons)

- Nonmetals gain electrons until they do the same.

- Both go to s2p6 - 8 valence electrons - called a ______

- The tendency to arrange electrons so each atom has 8 is called the ______

- The formation of an ionic bond:

Na 1s 2s 2p 3s

Cl 1s 2s 2p 3s 3p

an easier way.....

- The ionic bonding picture looks like this....

Ex1: Na to Cl =

Ex2: Ba to Cl

0bbbbff75f5c734da32b162fe62be90a.doc Page 6 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Ex3: Al to N

Ex4: Na to S

The easy way: - Find the charge of each atom - “criss cross” the charges – charge cancels out and you are left with a neutral compound

Formula Name EX1: Al N

EX2: Na S

EX3: Al S

-1 EX4: Li NO3

-1 EX5: Ca C2H3O2

EX6: Magnesium and Phosphite

EX7: Aluminum and hyponitrite

EX 8: Calcium bromide

EX 9: Aluminum Sulfide

- Energy is involved in all ______

Na + Cl yields NaCl + 769 kJ

- Lattice energy - energy released when an ______forms.

NaCl = - 769 kJ/mole NaF = - 922 kJ/mole KCl = -718 kJ/mole

smaller ions have ______

- Property summary of ionic compounds: o ______o ______o ______o ______o ______

0bbbbff75f5c734da32b162fe62be90a.doc Page 7 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding

0bbbbff75f5c734da32b162fe62be90a.doc Page 8 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Metallic Bonding - “Sea of electrons theory”  The nuclei are arranged in a systematic lattice.

 The bond strength relies on the nuclear charge and the number of valence e-  Ex. Mg is stronger than Na

 The valence electrons form a sea of free moving electrons that are attracted to multiple positive nuclei.

Cu+ Cu+ Cu+ Cu+ 2 2 2 2

 Conducts Electricity as a result of free electrons.

 Malleability and ductility results from the nuclei's ability to move passed each other

Remember – in ionic bonds some atoms want e- and some don’t – in covalent bonds, all atoms share – in metals, no one atom wants the e-

Covalent Bonding

0bbbbff75f5c734da32b162fe62be90a.doc Page 9 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding In covalent bonding atoms share electrons. In the H2 molecule, each H atom says, "I only need one more e- to be like a noble gas (helium)." Since each hydrogen has only one electron, when two hydrogens bond they can share their electrons.

Molecule –

- monatomic molecules - ______

- diatomic molecules - ______

- polyatomic molecules - ______

- The formation of a covalent bond:

- Bond Length vs. Bond Energy

 Bond length = ______Bond Energy

- Diatomic Molecules and Orbital Notation (Orbital overlap or notatation diagrams):

H2 1s 1s

O2 1s 2s 2p

1s 2s 2p

N2 1s 2s 2p

1s 2s 2p

- Octet Rule- ______

0bbbbff75f5c734da32b162fe62be90a.doc Page 10 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding - Electron cloud representations:

F2 HCl

- HF - orbital notation diagram

F 1s 2s 2p

Lewis Dot Diagrams of molecules (covalent compounds) and polyatomic ions

Basic rules (try to use as many as the rules as possible)

1. Each atom wants 8 electrons (except H wants 2). 2. Each atom goes for close to the right # of bonds. 3. The least electronegative atoms goes in the middle OR 4. The atom that makes the most bonds goes in the middle. (H will always go on the outside.) OR 5. The “single guy” (the atom that does not have a subscript after it) goes in the middle.

- Other notes o Symmetry is key!!! o Place the atoms in order (left, right, bottom, and top) around a central atom. o S= N-A (s= shared electrons -# bonds, N= needed electrons – all need 8 except H which needs 2, A= # electrons actually have – valence e-) o Molecules with a charge . If using S = N-A/2, add the charge into the Actual amount of electrons . Put [] around the molecule and inclue the charge

0bbbbff75f5c734da32b162fe62be90a.doc Page 11 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Examples: Draw the following Lewis structures

Ex1: CH4

Ex2: H2O

Ex3: PCl3

Ex4: SiH2F2

Ex5: CS2

Ex6: C2H6

Ex7: C2H4

Ex8: C2H2

Ex9: CH2O

Ex10: HCN

Ex11: FON

0bbbbff75f5c734da32b162fe62be90a.doc Page 13 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Drawing polyatomic ions: count electrons - if the charge is - 3, add 3 electrons

-3 example PO4

less bonds than atoms want = negative charge more bonds than atoms want = positive charge

P wants 3 bonds, has 4 - + 1 charge Each O wants 2, has 1 - so each O = -1 Total = - 3

-3 Ex11: PO4

coordinate covalent bond - 2 shared electrons in a bond are donated by 1 atom

Ex12: NH4+

Ex13: OH-1

Ex14: sulfate

Ex15: nitrate

Ex16: nitrite

Ex17: carbonate

Ex18: bicarbonate

Ex19 H2SO4

Ex20: H3PO4

The Properties of Molecular Compounds

0bbbbff75f5c734da32b162fe62be90a.doc Page 15 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Valence shell electron pair repulsion theory (VESPER) – e- pairs get as far away from each other as possible Example Shared Lone Shape Example Angle(s) and drawing pairs pairs AB 1 0 Linear HF

AB2 2 0 Linear CO2

AB2E 2 1 Bent SO2

AB2E2 2 2 Bent H2O H2S

AB3 3 0 Triangular CH2O Planar

AB3E 3 1 Triangular NH3 pyramidal

AB4 4 0 Tetrahedron CH4

AB5 5 0 Triangular PF5 Bipyramidal

AB6 6 0 Octahedron SF6

0bbbbff75f5c734da32b162fe62be90a.doc Page 16 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Examples: Predict the shapes of the following (show all work):

Ex1: CCl4

Ex2: HBr

Ex3: SO3

Ex4: SO2

Ex5: H2S

Ex6: NH3

-1 Ex7: ClO4

Ex8: PF5

0bbbbff75f5c734da32b162fe62be90a.doc Page 18 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Intermolecular forces (IMF)- forces that hold molecules together

- happens between ______compounds

- intermolecular forces - can be ______

Intramolecular forces – chemical bonds (ionic, covalent, metallic)

- happens within a molecule or compound

- always ______

H ------Cl H ------Cl

Types of IMF

1. dipole-dipole - dipole - when electrons are ______distributed

Ex1: predict the IMF that occurs with HCl

Ex2: predict the IMF that occurs with H2S

2. hydrogen bonding - H-bonding is a “super-duper” dipole-dipole

- Ex3: predict the IMF that occurs with HF

0bbbbff75f5c734da32b162fe62be90a.doc Page 19 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding - Are we having FON? - H-bonding happens any time H is bonded to ______

- Why? A large difference in ______between F, O, or N and H results in one end of the molecule being very ______, while the other end is very ______.

- Why N and not Cl? They have identical electronegativities! Well, N is so much ______than Cl so the negative charge is spread over a smaller area which exerts more force.

- Effect of H-bonds on physical properties:

H-bonding tends to cause the following in substances:

 Boiling Point  Heat of Vaporization  Vapor Pressure  Melting Point

Also, H-bonds causes water to expand when it freezes. H-bonding is also responsible for the shapes of proteins.

We learned polar molecules have ______holding them together.

We learned about H-bonding or “super” ______

These two types of IMF usually result in substances being solids or liquids at room temp.

Most nonpolar covalent substances are ______at room temp. as the forces holding them together are not ______enough to keep the molecules attracted - hence they are ______

O2, H2, N2 - straight nonpolar substances

CO2 - have dipoles, but nonpolar due to its molecular geometry

Now, a third type of IMF

3. Van der Waals Forces (London Forces) - Temporarily induced dipoles caused by the motion of electrons.

more electrons = more attraction so, bigger atoms have stronger Van der Waals forces

0bbbbff75f5c734da32b162fe62be90a.doc Page 20 of 21 Accelerated Chemistry Chapter 6 Notes – Manipulating Polyatomic Ions and Chemical Bonding Summary

IMF Molecule Type Molecule Boiling Pt. (Co)

London Noble Gas He -269

London Noble Gas Ar -186

London Nonpolar H2 -253

London Nonpolar O2 -183

Dipole-dipole Polar HI -34

H-bonding Polar HF 19.5

Ionic NaCl 1413

Ionic MgF2 2237

Metallic Cu 2567

Metallic Fe 2750

Bond Energy - basic idea - what is the strength of chemical bonds? bond energy - energy needed to break a bond - measured in kJ/mole

bond strength and stability: stronger bond - more stable -needs more energy to break the bond weaker bond - takes little energy to break the bond so the chemical is unstable

chemical changes favor lower energy states - exothermic reactions are favored

Bond Strength

which is stronger? - single, double, or triple bond?

which is shortest bond length? s, d, or t?

which is stronger, short or long bonds?

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