1. Ionic & Metallic Bonding
Chapter 7

2. How are ions formed?
An ion is an atom that has lost or gained electrons
BUT, not just ANY electrons… valence electrons!
VALENCE ELECTRONS – electrons in the highest occupied energy level of an element’s atom
Valence electrons are the only electrons used in chemical bonds

3. How do you find valence electrons?
To find the valence electrons for a representative element (A Groups), look at the group number.
Periodic Table Group
Valence Electrons
Group 1A (Alkali metals) 1
Group 2A (Alkaline Earth metals) 2
Group 3A (13) Boron Family 3
Group 4A (14) Carbon Family 4
Group 5A (15) Nitrogen Family 5
Group 6A (16) Chalcogens 6
Group 7A (17) Halogens 7
Group 8A (18) Nobel Gases 8

4. How do you find valence electrons?
To find the valence electrons of transition elements (B Groups), look at the electron configuration.
Element
Electron Configuration
Valence Electrons Zn
[Ar] 4s2 3d10 2 Ag
[Kr] 5s14d10 1
Remember that the number of valence electrons for transition elements CAN change!

5. Ions
Two types of ions:
Cations - formed when an atom loses its valence electrons
Positively charged ion
(more protons than electrons)
Anions - formed when an atom gains valence electrons
Negatively charged ion
(more electrons than protons)

6. Naming Ions Cations: Anions: Metals are always cations
The name of a cation is the same as that of the originial atom
EXAMPLE: Na - sodium atom; Na1+ - sodium ion
Anions:
Nonmetals are always anions
The name of an anion always ends in -ide
EXAMPLE: F - fluorine atom; F1- - fluoride ion

7. Ion Formation Equation
Equations to show the transfer of electrons:
Na Na e-
Sodium atom yields sodium ion plus one electron.
O + 2 e O2-
Oxygen atom plus two electrons yields an oxygen ion.

8. P Ba Zn Br Xe Practice: P3- + 3 e- Ba2+ + 2 e- Zn2+ + 2 e- + 1 e- Br1-
Write an equation for the formation of an ion for the following atoms: P Ba Zn Br Xe
P3-
+ 3 e-
Ba2+
+ 2 e-
Zn2+
+ 2 e-
+ 1 e-
Br1-
Xe0

9. Ionic Bonds & Ionic Compounds
Electrostatic forces that hold ions together in ionic compounds
Ionic compounds:
Compounds composed of cations & anions
total positive charge = total negative charge
Electrically neutral compound
CHEMICALLY combined

10. Examples of Ionic Compounds
NaCl - sodium chloride (salt)
Fe2O3 - iron (III) oxide (rust)

11. Octet Rule
In forming compounds, atoms tend to achieve the electron configuration of a noble gas.
Octet – set of 8
Both atoms in the compound WANT to have eight valence electrons in the highest energy level

12. How to atoms fulfill the Octet Rule in an IONIC compound?
Atoms of metallic elements LOSE their valence electrons, leaving a complete octet in the next lowest energy level.
Example: Sodium (Na)
Has 1 valence electron (Group 1A)
Has a total of 11 electrons
3 Energy Levels:
1st energy level: 2 electrons
2nd energy level: 8 electrons
3rd energy level: 1electron
When it loses its 1 valence electron, it will be left with 8 in the next lowest energy level.

13. How to atoms fulfill the Octet Rule in an IONIC compound?
Atoms of some nonmetallic elements tend to GAIN electrons to achieve a complete octet.
Example: Chlorine (Cl)
Has 7 valence electrons (Group 7A)
Has a total of 17 electrons
3 Energy Levels:
1st energy level: 2 electrons
2nd energy level: 8 electrons
3rd energy level: 7 electrons
When it gains 1 valence electron, it will be have a total of 8 valence electrons in the highest energy level.

14. Fulfilling the Octet Rule
When a cation (metal) and an anion (nonmetal) combine to form an ionic compound, they both achieve a noble gas electron configuration.
Example: NaCl – Sodium Chloride (Salt)
Na must lose 1 electron while Cl must gain 1 electron
Therefore: NaCl is made up of a Na1+ ion & a Cl1- ion
Electron Configurations:
Na1+ (10 electrons) - 1s22s22p6 (Same as Neon)
Cl1- (18 electrons) - 1s22s22p63s23p6 (Same as Argon)

15. Ionic Compounds
A Chemical Formula represents the composition of substances by showing the kinds and numbers of atoms in the smallest representative unit of a substance.
Ca + Br  Ca2+ + Br1-  CaBr2
Mg + O  Mg2+ + O2-  Mg2O2  MgO

16. Forming Ionic Compounds
1. Determine the oxidation number for each element or ion in the compound.
2. Cross the numbers to become the subscripts and drop the + or – sign.
3. Reduce subscripts if possible.
Beryllium + Sulfur
Be  Be2+
S  S2-
Be2+ S2-  Be2S2
Be2S2 reduces to Be1S1
Compound: BeS

17. Practice: Lithium + Selenium Potassium + Fluorine Li1+ Se2-  Li2Se
Write the formula for combining the following elements:
Lithium + Selenium
Potassium + Fluorine
Calcium + Nitrogen
Strontium + Oxygen
Li1+ Se2-  Li2Se
K1+ F1-  KF
Ca2+ N3-  Ca3N2
Sr2+ O2-  Sr2O2  SrO

18. What about with Polyatomic Ions?
Polyatomic ions have a specific charge!
Use your reference tables.
You cannot change the subscripts that are with a polyatomic ion – you must put it in (parentheses)!
Example:
Calcium + Hydroxide
Ca OH1-
If you DON’T use the parentheses around the OH then you only have
1oxygen and 2 hydrogen's
Ca(OH)2

19. Ionic Compounds
Ionic compounds exists as a collection of positively and negatively charged ions in repeating patterns
Therefore, its chemical formula refers to a ratio.
A Formula Unit is the lowest whole-number ratio of ions in an ionic compound.
NaCl – 1:1 ratio
MgCl2 – 1:2 ratio
AlBr3 – 1:3 ratio

20. Properties of Ionic Compounds
MP: 801 oC (1074 K)
Solubility in Water:
35.6 g/100 mL (0 °C) g/100 mL (25 °C) g/100 mL (100 °C
Most are crystalline solids at room temperature.
Typically have high melting points.
Can conduct an electric current when melted or dissolved in water.
Many are soluble in water.
Example:
Sodium Chloride

21. Bonding in Metals Metals can bond in two different ways:
1. Ionic Bonding
bond between a metal (cation) and a nonmetal (anion)
CHEMICAL combination of ions
2. Metallic Bonding
The attraction of free-floating valence electrons for the positively charged metal ions.
Occurs between two metal atoms.
PHYSICAL combination of atoms

22. Metallic Bonding Metallic bonding explains why metals are…
Good Conductors
Transfers heat or electricity easily.
Ductile
Can easily be drawn into wires.
Malleable
Can be hammered or forced into shapes.

23. Why do metals have these properties?
Their valence electrons are mobile and drift freely from one part of the metal to another.
Valence electrons of metal atoms are loosely held by the positively charged nucleus.
Valence electrons are released into a “SEA OF ELECTRONS” shared by all of the metal atoms.

24. Metals are… Because… Crystalline solids Crystal
Atoms arranged in very compact and orderly patterns
Crystal
Regular, repeating arrangements of atoms, ions, or molecules
Because…
This arrangement helps save space while allowing as many atoms to be stacked as possible.

25. Shapes of Metals Simple Cube Body-centered cubic Face-centered cubic
Hexagonal close-packed

26. Alloys
Alloys are MIXTURES composed of two or more elements, at least one of which is a metal.
They are important because their properties are often superior to those of their component elements.
Alloys are PHYSICALLY combined, meaning that they can be separated by physical means (i.e. melting).

27. Examples of Alloys Cast Iron Stainless Steel Brass Surgical Steel
-iron & carbon
Stainless Steel
-iron, chromium, carbon, & nickel
Brass
-copper & zinc
Surgical Steel
-iron, chromium, nickel, & molybdenum
Sterling Silver
-silver & copper

28. REVIEW: What is an ionic compound? What are the two types of ions?
What are the characterisitics of ionic compounds?
How do metallic bonds differ from ionic bonds?
Cation + Anion
Cation (Metals) – lose electrons
Anion (Nonmetals) – gain electrons
High melting points
Soluble in water
Conduct electricity when melted or dissolved in water
Crystlline solids at room temp.
Metallic bonds are physically combined; Ionic bonds are chemically combined.