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IONIC COMPOUNDS. Chapter 5.8. IONIC COMPOUNDS. Recall: Metals form positive ions (+) and non-metals form negative ions (-). 1-. 1+. Cl. Na. IONIC COMPOUNDS. When ions like NaCl form, they make an ionic bond . - PowerPoint PPT Presentation
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IONIC COMPOUNDS
Chapter 5.8
IONIC COMPOUNDSRecall: Metals form positive ions (+)
and non-metals form negative ions (-).
Na
1+ Cl
1-
IONIC COMPOUNDS When ions like NaCl form, they make
an ionic bond. Ionic bond – the attraction between a
positive metal ion and a negative non-metal ion.
Na
1+ Cl
1-
Like most ionic compounds, NaCl can form a crystalline structure
Just like most things in nature, these
Na
1+ Cl
1-
NaCl
Ionic bonds Ionic compounds have certain
characteristics because of their ionic bonds: Most are crystalline solids at room
temperature. Ionic compounds generally have high
melting points. Can conduct an electric current when
dissolved in water (electricity can “jump” between the negative and positive charges).
Just like most things in nature, the charges in ionic compounds must balance out. Ex. Sodium ion is 1+, Chloride ion is 1-
so they balance out. What about calcium and chloride?
Na
1+ Cl
1-
NaCl
Calcium atom becomes Calcium ion with a charge of _____.
Chlorine atom becomes Chloride ion with a charge of _____.
So how will they form a compound?
One calcium ion will bond with two chloride ions so that the charges balance out.
2+
1-
Ca2+Cl -Cl - CaCl2
Recall – use subscripts to show how many of each atom are in a compound.
CaCl2 calcium chloride
Science 10 – Nov. 24th Draw Bohr diagrams for atoms and
stable ions for: Mg, S, Na, F
WRITING FORMULAS OF IONIC COMPOUNDS
EXAMPLE 1- What is the formula for the ionic compound of calcium and fluorine?
Step 1 – Write the symbols of the elements with the metal first and non-metal second
Ca FStep 2 – Write the ion charge of each
element Ca2+ F-1
Step 3 – Determine how many of each you need to have an overall charge of zero.
Ca+2 F-1 F-1
Step 4 - Write the formula using subscripts, after the element, to indicate how many you used.
Ca1F2 CaF2 ( 1 is not needed )
EXAMPLE 2 What is the formula for the ionic
compound of aluminum and sulfur? Steps:1) Al S2) Al+3 S-2
3) Al+3 Al+3 S-2 S-2 S-2
4) Al2S3
CRISS-CROSS RULE Al+3 S-2
Al2S3
Watch out for lowest terms: Mg+2 O-2
Mg2O2 MgO
WRITING NAMES OF IONIC COMPOUNDS
When naming an ionic compound we simply write the name of the metal first and non-metal second. We change the ending of the non-metal name so that it ends in “ide.”
EXAMPLES 1) NaCl – sodium Chloride 2) CaBr2 – calcium bromide 3) MgO – magnesium oxide
HOMEWORK Read pages 192-194 Questions page 195 #1a, 3,4,5,6
Science 10 – Nov. 15th Write the chemical formula and
chemical name for the compound formed by chlorine and calcium.