Chemistry Regents
Mr. Markic
Page 1 of 6
Chapter 7 - Ionic and Metallic Bonding
Ions
How does an atom become an ion and what charge does it become?


What elements lose an electron and what are they called?


What elements gain electrons and what are they called?

Why do the elements lose electrons?


Why do the elements gain electrons?


What are valence electrons?

Practice Problems
How many valence electrons are in each atom?
a) Potassium
b) Carbon
c) Magnesium
d) Oxygen
Electron dot structure of some representative elements
H
He
Li
Be
O
F
Ne
Na
Mg
S
Cl
Ar
Chemistry Regents
Mr. Markic
Page 2 of 6
The Octet Rule
In forming compounds atoms try to achieve the electron configuration of a noble gas
Why?
Metals want to
Nonmetals want to
Practice Problems
How many electrons will each element gain or lose in forming an ion?
a) Calcium
c) Aluminum
b) Fluorine
d) Oxygen
Write the name and symbol of the ion formed when
a) A potassium atom loses one electron
c) A fluorine atom gains one electron
b) A zinc atom loses two electrons
Ionic bonds
 composed of cations and anions called compounds
Cations Anions –
 Have opposite charges (+) and (-)and attract each other – electrostatic force
 Transfer of electrons
 Electrically neutral
Cations
Metals tend to lose electrons
Na →
Mg →
Anions
Nonmetals tend to gain electrons
Cl + e- →
O
+
2e- →
Sample Problems
Na + Cl →
Mg +
Cl →
Chemistry Regents
Mr. Markic
Page 3 of 6
Use electron dot structures to predict the formulas of potassium and oxygen
K
O
Properties of Ionic Compounds
 Crystalline _____________ at room temperature
 Do __________ conduct electricity (__________)
 ____________ melting points
 Conduct _________________ (when dissolved in ___________)
Bonding in Metals (Metallic Bonding)
 A metal structure is of closely packed cations
 Metals bound to metals
 Are ductile, malleable, and good conductors of heat and
electricity
 The cation is surrounded by _____________________________
 free floating valence electrons
Alloys
 Mixtures that contain a metal & one or more ‘other’ elements
 Superior properties
Examples:
Brass–
White gold–
Bronze –
Solder-
Chemistry Regents
Mr. Markic
Page 4 of 6
Ionic Formulas
Use the element’s oxidation number
Binary Ionic Formulas
Cation is first then anion
Examples
Na+ +
Cl-
→
Ca2+
Cl-
→
+
Al3+
+
O2-
→
Crisscross Method
1. Crisscross the charges in the monatomic ions
2. Drop the signs
3. Reduce to the simplest ratio (empirical)
Al 3+
+
O2-
→
Pb4+
+
O2-
→
Mg2+
+
O2-
→
Ca2+
+
P3-
→
K+
+
O2-
→
Polyatomic Ions
 Table E
 Composed of more than one atom
 Group of atoms that comprise a charge (ion)
Compounds with polyatomic ions
 Must be neutral
 Contains at least three elements
Al3+
+
PO43-
→
NH4+ +
SO42-
→
Na+
+
SO42-
→
K+
CrO42-
→
OH-
→
Ca2+ +
+
Chemistry Regents
Mr. Markic
Page 5 of 6
Naming Ions
Cations
 Write the name of the element followed by the word ion
Anions
 Write the root name of the element with an –ide ending followed by the word ion
Practice Problems
Write the name of the ion
K+
I-
S2-
O2-
Al3+
N3-
Mg2+
Multiple Oxidation States
 Naming is based on its oxidation number
 Roman numeral is assigned
 No roman numeral needed for only one oxidation number
Example
Mn2+
Mn4+
Mn7+
Naming Binary Compounds
 Name the cation first, followed by the anion name (ends in
Practice Problems
Name the following ions
CaCl2
NaF
Li2S
KI
Naming cations with multiple oxidation numbers
 Cation is named first
 The oxidation number is written in roman numeral after the cation
 The anion name is written
)
Chemistry Regents
Mr. Markic
Page 6 of 6
Practice exercise
Name the following ions
CuCl2
Au2O
Fe2O3
TiCl4
Naming Compounds with Polyatomic Ions
 1st write the symbol for the cation
 2nd write the formula for the polyatomic ion (found on table E)
Practice Exercise
Name the following compounds
NaOH
CaCO3
CuSO4
Fe(NO3)3
Writing formulas from names
• Determine the cation element symbol and oxidation state
•
If a roman numeral is given-it refers to the cations oxidation number
•
If a polyatomic ion is given, use table E to determine its symbol and charge
•
Cation is written first, then the anion
•
Use the criss-cross method to achieve a neutral compound
•
Always reduce subscripts (empirical)
Practice Problems
Write formulas for compounds formed from these pairs of ions.
a) Calcium acetate
c) Magnesium hydrogen carbonate
b) Sodium perchlorate
d) Chromium (III) nitrite