+ Ionic Bonds and Ionic Compounds Forming Compounds from Ions.
Ionic Bonding & Ionic Compounds. Objectives Explain how ionic compounds are formed Explain the...
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Transcript of Ionic Bonding & Ionic Compounds. Objectives Explain how ionic compounds are formed Explain the...
Ionic Bonding & Ionic Compounds
Objectives Explain how ionic compounds are
formed Explain the electrical charge of an ionic
compound Describe three properties of ionic
compounds
Important Vocabulary Ionic compounds Ionic bonds Chemical formula Formula unit Coordination number
Formation of Ionic Compounds
Compounds composed of cations and anions are called ionic compounds
They usually are the combination of a metal cation with a non-metal anion
For example: sodium chloride Although they are composed of ions,
ionic compounds are electrically neutral The total positive charge of the cations
equals the total negative charge of the anions
Ionic Bonds Opposite charges attract This attraction causes cations and
anions to bind together forming an ionic bond
An ionic bond is a chemical bond formed between two ions of opposite charges
Formation of an Ionic Bond
Formula Units Chemists represent the composition of
substances by writing chemical formulas
A chemical formulas shows the kinds and numbers of atoms in the smallest representative unit of a substance
A formula unit is the lowest whole-number ratio of ions in an ionic compound
Formula Units Example NaCl
is 1 sodium ion & 1 chloride ion The whole-number ratio is 1:1
MgCl2 is 1 magnesium ion & 2 chloride ions The whole-number ratio is 1:2
Why?
Practice Problems Use electron dot structures to predict the
formulas of the ionic compounds formed from the following elements
1. Potassium and oxygen
2. Magnesium and nitrogen
3. Sodium and bromine
4. Aluminum and oxygen
Properties of Ionic Compounds
Most are crystalline solids at room temperature The component ions within these crystals are
arranged in repeating 3-D patterns The coordination number of an ion is the
number of ions of opposite charge that surround the ion in a crystal
They usually have high melting points and boiling points
They also can conduct electricity when dissolved in water or melted
Ionic Compound Crystals
Ionic Compound Crystals
Coordination Number
In sodium chloride, (NaCl) Na+ ion has a coordination number of 6 because each one is surrounded by 6 Cl- ions
In titanium (IV) oxide, (TiO2) the coordination number for O2- ion is 3 because it is surrounded by 3 Ti4+ ions
Conduction of Electricity
Why can dissolved or melted ionic compounds conduct electricity?