Chemistry: Ionic Charges, Polyatomic Ions, and Molecular Nomenclature

Fixed charge for Al

3+

Fixed charge for Zn

2+

Fixed Charge for Cd

2+

Fixed Charge for Ag

1+

Ammonium

NH₄⁺

Hydronium

H₃O⁺

Mercury (l)

Hg₂²⁺

Is Ammonium a cation or anion?

Cation

Is hydronium a cation or a anion?

Cation

Is mercury (l) a cation or anion?

Cation

Acetate

C₂H₃O₂⁻

Azide

N₃⁻

Carbonate

CO₃²⁻

Chlorate

ClO₃⁻

Chlorite

ClO₂⁻

Chromate

CrO₄²⁻

Cyanide

CN⁻

Dichromate

Cr₂O₇²⁻

Dihydrogen Phosphate

H₂PO₄⁻

Hydrogen carbonate or bicarbonate

HCO₃⁻

Hydrogen Phosphate

HPO₄²⁻

hydrogen sulfate or bisulfate

HSO₄⁻

Hydroxide

OH⁻

Hypochlorite

ClO⁻

Nitrate

NO₃⁻

Nitrite

NO₂⁻

Oxalate

C₂O₄²⁻

Perchlorate

ClO₄⁻

Permangante

MnO₄⁻

Peroxide

O₂⁻²

Phopshate

PO₄³⁻

Phosphite

PO₃³⁻

Sulfate

SO₄²⁻

Sulfite

SO₃²⁻

Thiocyanate

SCN⁻

What is a polyatomic ion?

Consists if a combination of two or more atoms

What is a Oxoanion?

Polyatomic ions containing oxygen

If two atoms have similar IE and EA

electrons will not completely transfer from one to another (i.e. will not form ions).

Instead, electrons are shared between atoms to give each atom a noble gas config.

Diatomic Molecules

Diatomic molecules contain two atoms and can be either heteronuclear or homonuclear.

Binary molecular compounds/ covalent compounds

consist two different non-metals

Mono-

1

Di-

2

Tri-

3

Tetra-

4

Penta-

5

Hexa-

6

Hepta-

7

Octa-

8

Nona-

9

Deca-

10

Ammonia

NH₃

Acid

substance that produces hydrogen ions (H+ , proton) when dissolved in water

Binary acids

Contain hydrogen and a monoatomic anion

Oxoacids

when dissolved in water, produce hydrogen ions and their corresponding oxoanions

-ite

-ous acid (sprITE is delicOUS)

-ate

-ic

Hydrates

compounds that have a specific number of water molecules within its solid structure

The Octet Rule

atoms will lose, gain, or share electrons in order to achieve a noble gas electron configuration

Bond length

Bond length is the distance between the nuclei of two covalently bonded atoms.

Bond Strength

We quantify bond strength by measuring the quantity of energy required to break it

Polarity

Covalent and ionic bonds are two extremes of bonding. In fact, some ionic compounds have covalent bonding. Bonding can vary with the degree of e- pair sharing

Nonpolar covalent bond

e - pair shared equally between 2 bonded atoms • homonuclear diatomic (H2 , N2 , O2 , F2 , Cl2 , Br2 , I2 ) • 2 atoms with identical IE and EA

Homonuclear Diatomer

(H2 , N2 , O2 , F2 , Cl2 , Br2 , I2 )

polar covalent bond

e - pair shared unequally between 2 bonded atoms • e - pair is closer to one atom than the other

Electronegativy

Electronegativity is the ability of an atom in a compound to pull electrons to itself

The greater the electronegativity difference between two atoms, the more polar is the bond.

➢A bond between atoms whose electronegativities differ by less than 0.5 is generally considered purely covalent or nonpolar.

➢A bond between atoms whose electronegativities differ by the 0.5 to 2.0 is generally considered polar covalent.

➢A bond between atoms whose electronegativities differ by 2.0 or more is generally considered ionic

Dipole

is the separation of electrical charge created when atoms with different electronegativity form a covalent bond

Magnitude of dipole

=Dipole moment

extent of polarity depends on

electronegativity difference between the 2 atom

the larger the electronegativity difference

the larger the dipole moment

For hydrogen halides, the smaller the bond length

the larger the dipole, the more polar the bond.

- Because electronegativity decreases down a group.

Expanded octet

observed for nonmetals in period 3 and beyond

Lewis Structure

theoretical explanations of structures

How to find Formal Charge?

Formal Charge = valence e - − nonbonding e- − bond lines

What atom can have a negative FC

the more electronegative atom

Resonance Structures

two or more equally valid Lewis structures for one molecule/ion

Bond Order

Bond order = number of bonds on central atom number of terminal atoms

High Bond Order

Higher bond order = shorter bonds = higher bond energy = more e- being shared = atoms closer together

Bond Order 1,2,3

Bond order = 1 → single bond

Bond order = 2 → double bond

Bond order = 3 → triple bond

Expanded Octet

The central atom has more than eight electrons.

Incomplete Octet

The central atom has fewer than eight electrons due to a shortage of electrons. e.g. Be and B

Odd numbers of electrons

The central atom has fewer than eight electrons due to an odd number of electrons.

-Free radicals (very reactive):e.g. NO, NO2 , ClO3

-Best structure is the one that minimize the Formal charge