AP Chem — Full Ion & Redox Reference

acetate

C₂H₃O₂⁻

aluminum

Al³⁺

ammonium

NH₄⁺

barium

Ba²⁺

bicarbonate

HCO₃⁻

bisulfate

HSO₄⁻

bisulfide

HS⁻

bisulfite

HSO₃⁻

bromate

BrO₃⁻

bromide

Br⁻

bromite

BrO₂⁻

calcium

Ca²⁺

carbonate

CO₃²⁻

chlorate

ClO₃⁻

chloride

Cl⁻

chlorite

ClO₂⁻

chromate

CrO₄²⁻ (yellow)

chromium

Cr³⁺

cupric

Cu²⁺ (blue)

cuprous

Cu⁺ (green)

cyanide

CN⁻

dichromate

Cr₂O₇²⁻ (orange)

ferric

Fe³⁺ (yellow)

ferrous

Fe²⁺ (green)

fluoride

F⁻

hydrogen

H⁺

hydronium

H₃O⁺

hydroxide

OH⁻

hypobromite

BrO⁻

hypochlorite

ClO⁻

hypoiodite

IO⁻

iodate

IO₃⁻

iodide

I⁻

iodite

IO₂⁻

lead

Pb²⁺

lithium

Li⁺

magnesium

Mg²⁺

manganese

Mn²⁺

mercuric

Hg²⁺

mercurous

Hg₂²⁺

nickel

Ni²⁺ (green)

nitrate

NO₃⁻

nitride

N³⁻

nitrite

NO₂⁻

oxalate

C₂O₄²⁻

oxide

O²⁻

perbromate

BrO₄⁻

perchlorate

ClO₄⁻

periodate

IO₄⁻

permanganate

MnO₄⁻ (purple)

peroxide

O₂²⁻

phosphate

PO₄³⁻

phosphide

P³⁻

phosphite

PO₃³⁻

potassium

K⁺

silver

Ag⁺

sodium

Na⁺

stannic

Sn⁴⁺

stannous

Sn²⁺

strontium

Sr²⁺

sulfate

SO₄²⁻

sulfide

S²⁻

sulfite

SO₃²⁻

thiocyanate

SCN⁻

thiosulfate

S₂O₃²⁻

zinc

Zn²⁺

hydrogen phosphate

HPO₄²⁻

dihydrogen phosphate

H₂PO₄⁻

Naming pattern: hypo–ite → per–ate

hypochlorite ClO⁻ → chlorite ClO₂⁻ → chlorate ClO₃⁻ → perchlorate ClO₄⁻ (charge stays –1, oxygens go 1→2→3→4)

“-ite” vs “-ate”

“-ite” has ONE FEWER oxygen than “-ate”; the charge is the same. (nitrite NO₂⁻ / nitrate NO₃⁻)

What does the prefix “bi-” or “hydrogen” do?

Adds one H⁺ and raises the charge by +1: CO₃²⁻ → HCO₃⁻, SO₄²⁻ → HSO₄⁻, S²⁻ → HS⁻

What does the prefix “thio-” mean?

One oxygen is replaced by a sulfur: SO₄²⁻ → S₂O₃²⁻ (thiosulfate), CN⁻ → SCN⁻ (thiocyanate)

“-ous” vs “-ic” endings

“-ous” = LOWER charge, “-ic” = HIGHER charge. ferrous Fe²⁺ / ferric Fe³⁺; cuprous Cu⁺ / cupric Cu²⁺; stannous Sn²⁺ / stannic Sn⁴⁺; mercurous Hg₂²⁺ / mercuric Hg²⁺

Which ion is the weird one — it travels as a pair?

mercurous, Hg₂²⁺ — two mercury atoms bonded together sharing a 2+ charge

Colored ions to know

CrO₄²⁻ yellow • Cr₂O₇²⁻ orange • MnO₄⁻ purple • Cu²⁺ blue • Cu⁺ green • Fe³⁺ yellow • Fe²⁺ green • Ni²⁺ green

Always soluble (memorize)

Alkali metal ions (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺), NH₄⁺, NO₃⁻, ClO₃⁻, ClO₄⁻, C₂H₃O₂⁻, HCO₃⁻

Cl⁻, Br⁻, I⁻ — solubility

Soluble EXCEPT with Ag⁺, Pb²⁺, Hg₂²⁺ (mnemonic: AP/H)

F⁻ — solubility

Soluble EXCEPT with Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺, Mg²⁺ (mnemonic: CBS-PM)

SO₄²⁻ — solubility

Soluble EXCEPT with Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺ (mnemonic: CBS/PBS). Your class handout also adds Ag⁺ and Hg₂²⁺.

O²⁻ and OH⁻ — solubility

INSOLUBLE except alkali metal ions and NH₄⁺. Ca²⁺, Sr²⁺, Ba²⁺ (CBS) are somewhat soluble.

CO₃²⁻, PO₄³⁻, S²⁻, SO₃²⁻, C₂O₄²⁻, CrO₄²⁻ — solubility

INSOLUBLE except with alkali metals and NH₄⁺

Mnemonic: AP/H

Ag⁺, Pb²⁺, Hg₂²⁺ — the halide exceptions

Mnemonic: CBS-PM

Ca²⁺, Ba²⁺, Sr²⁺, Pb²⁺, Mg²⁺ — the fluoride exceptions

Mnemonic: CBS/PBS

Ca²⁺, Ba²⁺, Sr²⁺, Pb²⁺ — the sulfate exceptions

H₂CO₃ → ?

CO₂ + H₂O (carbonic acid decomposes; bubbles are the tell)

H₂SO₃ → ?

SO₂ + H₂O

2 HNO₂ → ?

NO + NO₂ + H₂O

NH₄OH → ?

NH₃ + H₂O

Which species leave solution as gases?

H₂CO₃ (→CO₂), H₂SO₃ (→SO₂), HNO₂ (→NO + NO₂), NH₄OH (→NH₃), plus H₂S and HCN

The 8 strong acids

HCl, HBr, HI, HClO₄, HClO₃, HNO₃, H₂SO₄, HIO₄ — everything else is weak

HCl

hydrochloric acid (strong)

HBr

hydrobromic acid (strong)

HI

hydroiodic acid (strong)

HClO₄

perchloric acid (strong)

HClO₃

chloric acid (strong)

HNO₃

nitric acid (strong)

H₂SO₄

sulfuric acid (strong)

HIO₄

periodic acid (strong)

Common weak electrolytes to watch for

Weak acids (esp. HC₂H₃O₂ acetic and HF hydrofluoric), ammonium hydroxide (NH₄OH → NH₃(aq)), and water itself

Driving forces for a double replacement reaction

1) an insoluble solid (precipitate), 2) a weak electrolyte (H₂O or a weak acid), 3) gas formation. No driving force = no reaction.