Unit 9.5 Ionic & Metallic Bonding
Test Wed. 2/15
Why do atoms form bonds?
• to have the most stable electron configuration
for its electrons
• to achieve a lower, more stable, energy state
How atoms bond with each other depends on:
e
e
e
e
Electronegativity
Ionization Energy
# Valence Electrons
Valence electrons
• To find the of valence electrons in an atom of
a representative element, look at the last digit
of its group number.
Electron dot structure
• Also called “Lewis
valence electron dot
structure”
Octet rule
• In forming compounds, atoms tend to achieve the
electron configuration of a noble gas
• Fill up their highest energy level with 8 electrons OR
• Empty their highest energy level to Zero electrons
cation
I’m “paws-itive”
• A positively charged
ion, or cation, is
produced when an
atom loses one or more
valence electrons.
Formation of a cation
Watch This
anion – formed when an atom
gains valence electrons
• Nonmetals attain noble-gas configurations by
gaining electrons.
“losers on the left”
GAIN
VALENCE
ELECTRONS
LOSE VALENCE ELECTRONS
PRACTICE
How many valence electrons?
• Potassium
• Carbon
• Magnesium
• Oxygen
Ionic compound
• Composed of cations and anions
Ionic compounds are electrically neutral.
IONIC BOND
an electrostatic* force that holds ions together in ionic compounds
*Electrostatic refers to the attraction between opposite charges
Ionic bonding video 1
Ionic bonding video 2
Ionic boding video 3
Chemical formula
• Shows the number of each element in the
smallest representative unit of a substance.
Writing Lewis Dot Structures - Ionic
• Metals tend to lose e- while nonmetals tend to gain
electrons
hyperphysics.phy-astr.gsu.edu
Writing Lewis Dot Structures – Ionic Bonds
• Metals tend to lose e- while nonmetals tend to gain
electrons
chemistry58.wikispaces.com
Ionic bonds
Polyatomic Ions
• covalently bonded
group of atoms, with a
+ or - charge
• Watch this
23
WRITING FORMULAS FOR IONIC
COMPOUNDS :
1. Write the symbol for each ion. Positive ion goes
first.
2. Write the oxidation number for each ion above
the symbol.
•
For type 2 metals, the Roman numeral after the metal tells you
the oxidation number
3. Criss-cross the oxidation numbers (not the + or -).
These numbers become the subscripts.
4. If a subscript is needed for the PAI, you must
enclose it in parentheses first, then write the
subscript outside of the parentheses.
Tyler DeWitt Formula Writing
Writing Lewis Dot Structures –
Ionic Bonds
1.
2.
3.
4.
5.
Write the Lewis dot structure for each type of atom involved in the
compound.
Determine which atom will lose electrons (metal) and which atom will
gain electrons (nonmetal).
Draw arrows to show the electrons moving from the metal to the
nonmetal.
If an octet is not filled for the nonmetal or if you don’t use up all of the
metal’s valence electrons, you will need add more nonmetal or metal
atoms. Draw as many atoms of the metal as necessary to fulfill the octet
for the nonmetal and use all of the valence electrons from the metal.
Consolidate your diagram.
–
–
Draw the metal on the left with its charge in the upper right corner. (If more than one
of these was needed, write a coefficient in front of the metal.)
Draw the nonmetal with its octet. Enclose it in brackets. Include the charge outside of
the brackets in the upper right corner. (If more than one of these was needed, write a
coefficient in front of the nonmetal.)
Example:
• Write the formula for the compound that
contains aluminum and sulfur.
Example:
• Write the formula for the compound that
forms when sodium and oxygen combine.
Example:
• Write the formula for the iron (II) chloride.
Example:
• Write the formula for the compound that
contains calcium and phosphate.
WRITING NAMES FOR
IONIC COMPOUNDS
1. Write the name of the metal first.
2. IF THE METAL IS A TYPE 2 METAL, write the
oxidation number of the metal in parentheses. (You
will have to work backwards from the subscripts to
determine the oxidation number.)
3. Write the name of the nonmetal, changing
the ending to “ide.”
4. IF EITHER PART OF THE COMPOUND IS A
POLYATOMIC ION, write the name of the polyatomic
nonmetal from the chart. DO NOT CHANGE THE
ENDING OF THE PAI.
30
Example:
• Write the name for the compound that
contains lithium and nitrogen.
Example:
• Name this: NiF2
Example:
• Name this: Ca(C2H3O2)2
Properties of ionic compounds
(all related to the strong attraction between
the + and – charges)
• hard, crystalline solids at room temperature
• high melting points (and boiling points)
• good conductors – in aqueous solutions
(dissolved in water) and when molten
(melted)
not
crystalline
Metallic bonding
http://www.bbc.co.uk/schools/gcsebit
esize
Watch This
To describe the nature of
metallic bonding,
consider the valence
electrons of atoms in a
pure metal to behave as
a 'sea' of delocalized
electrons.
Metallic bond
• the forces of attraction between free-floating
(delocalized) electrons and positively charged
metal ions.
• Watch This
http://www.launc.tased.edu.au/online/sciences/PhysSci/pschem/metals/Met
als.htm
• Ductility – property of a metal that enables it
to be drawn into a wire
• Malleability- means that a metal can be
hammered into a sheet
Electrical conductivity
• To conduct an electric
current through the flow of
electrons
Thermal conductivity
• Transfer heat
video1
Video 2
alloy
• A mixture of 2 or more
metals
(KP p. 224) Alloys are important because their properties are often
superior to those of their component elements.
Really, we don’t hate you.
Percent Composition
• Percent Composition (% mass) is the
percentage by mass of each element in a
compound
Total mass of element
% Mass 
100
molar mass of compound
% Composition Practice
•
What is the percent of Li & O in Li2O?
What is the percent of each element in
Na2SO3?
How much sodium is in 25 grams
of Na2SO3 ?