Ion - for chem class

Ionic compounds

Ionic compounds

composed of positively and negatively charged ions held together by strong electrostatic forces. Result from the transfer of electrons from one element to another.

Covalent compounds

composed of individual molecules, discrete groups of atoms that share electrons. Result from the sharing of electrons between two atoms

bonding

the process of elements gaining, losing, or sharing electrons to attain the electronic configuration of the noble gas closest to them in the periodic table

types of elements that form ionic bonds

ionic bonds are formed between a metal on the left side of the periodic table and a nonmetal on the right side

ions

Charged species in which the number of protons and electrons in an atom is not equal.

cations

positively charged ions. A cation has fewer electrons than protons. Cations are formed by metals.

• for metals in groups 1A, 2A, and 3A, the group number = the charge on the cation

anions

newly updated

ion found in teeth and bones

Ca²⁺

2 ions found in body fluids

Na⁺ and K⁺

ion found in hemoglobin

Fe²⁺

ion present in gastric juices and other fluids

Cl⁻

ion needed for nerve transmission and muscle control

mg²⁺

3 steps to write a formula for an ionic compound

1. identify which element is the cation and which is the anion (use the group number of a main group element to determine the charge)

2. Determine how many of each ion type is needed for an overall charge of zero.

3. To write the formula, place the cation first and then the anion, and omit charges. (Use subscripts to show the number of each ion needed to have zero overall charge)

2 methods for naming cations of metals that form 2 different cations

Systematic Method: follow the name of the cation by a Roman numeral in parentheses to indicate its charge -or- Common Method: Use the suffix -ous for the cation with the smaller charge, and the suffix -ic for the cation with the higher charge. These suffixes are often added to the Latin names of the elements

How to name anions

Replace the ending of the element name by the suffix -ide

3 steps to name an ionic compound that contains a metal with a variable charge

1. Determine the charge on the cation

2. Name the cation and anion

3. Write the name of the cation first, then the anion

fixed charge of Al

Al³⁺

fixed charge of Mn

Mn²⁺

fixed charge of Co

Co²⁺

Fixed charge of Ni

Ni²⁺

Fixed charge of Zn

Zn²⁺

Fixed charge of Ag

Ag⁺

Fixed charge of Cd

Cd²⁺

Variable charges of Cr

Cr²⁺, Cr³⁺

Variable charges of Fe

Fe²⁺, Fe³⁺

Variable charges of Cu

Cu⁺, Cu²⁺

Variable charges of Sn

Sn²⁺, Sn⁴⁺

Variable charges of Au

Au⁺, Au³⁺

Variable charges of Pb

Pb²⁺, Pb⁴⁺

3 steps to derive a formula from the name of an ionic compound

1. identify the cation and anion and determine their charges

2. Balance the charges of the ions

3. Write the formula with the cation first, and use subscripts to show the number of each ion needed to have zero overall charge

general rule about boiling points and melting points of ionic compounds

They are extremely high because of the strong electrostatic bonds.

5 physical properties of ionic compounds

• high melting points

• high boiling points

• usually soluble in water

• their solutions conduct electricity

• they form crystalline solids

polyatomic ion

a cation or anion that contains more than one atom

formula for hydronium ion

H₃O⁺

formula for ammonium ion

NH₄⁺

formula for carbonate ion

CO₃²⁻

formula for sulfate ion

SO₄²⁻

formula for phosphate

PO₄³⁻

when to use suffix -ite

used for an anion that has one fewer oxygen atoms than a similar anion named with the -ate ending (ie. SO₄²⁻ is sulfate, but SO₃²⁻ is sulfite)

How to name anions that differ in presence of hydrogen

the word hydrogen or prefix bi- is added to the name of the anion. (ie. SO₄²⁻ is sulfate, but HSO₄⁻ is hydrogen sulfate or bisulfate)

formula for carbonate

CO₃²⁻

formula for Hydrogen carbonate or bicarbonate

HCO₃⁻

formula for Acetate

CH₃CO₂⁻

formula for Cyanide

⁻CN

formula for Nitrate

NO₃⁻

formula for hydroxide

⁻OHi

formula for Sulfate

SO₄²⁻