Section 1-3
Ionic Bonds
Habit Of The Mind
 #2 I teach my students to
manage impulses and delay
gratification to attain long term
goals.
Objectives
 L.1.3.1. Describe ions and explain how
they form.
 L.1.3.2. Explain how the formulas and
names of ionic compounds are written.
 L.1.3.3. Identify properties of ionic
compounds.
How Ions Form
 Atoms with 5-6-7 valence electrons will usually
accept enough electrons to increase that
number to 8 and become stable.
 Atoms with 1-2-3 valence electrons will usually
give up enough to lose their outer shell and be
left with a full valence set of electrons.
 These two types of atoms will become
electrically charged and are then called IONS.
How Ions Form
 When an atom loses an electron,
it loses a negative charge and
becomes a positive ion. When an
atom gains an electron, it gains a
negative charge and becomes a
negative ion.
 Objective L.1.3.1
How Do We Know If An Atom
Will Gain or Lose?
 The answer is in the number of valence
electrons. The atom will do whatever
requires less energy.
 Look at the following slide to decide what
requires the least amount of energy. The
obvious choice is the correct choice.
How Ions Form
Polyatomic Ions
 What does POLY mean?
 It means many.
 What does atomic mean?
 It means atom.
 What does Polyatomic mean?
 It means many atoms.
 A polyatomic ion is just a group of atoms (a molecule)
that behave like a single ion.
Polyatomic Ions
Ionic Bonds
 An ionic bond is the attraction between two
oppositely charged ions.
 Ionic bonds form as the result of attraction
between a positively charged ion and a
negatively charged ion. Obj. L.1.3.1
 A compound formed between a positive and
negative ion is called an Ionic Compound.
 Ionic compounds form between a metal and a
nonmetal.
Chemical Formulas And Names
 Compounds are represented by a chemical formula.
 What two pieces of information does a chemical
formula give you?
 It tells you which elements are in that compound by
giving you the chemical symbol for each element and,
 It tell you how many of each element are part of that
compound.
Formulas Of Ionic Compounds
 When ionic compounds form, the ions bond in such a
way as to balance the charges. The chemical formula of
the compound reflects this. L.1.3.2.
 A chlorine atom only needs to gain 1 electron to fill it’s
valence shell so the chloride ion will have a charge of -1.
 A magnesium ion wants to lose 2 electrons to shed it’s outer
shell so the magnesium ion will have a charge of +2.
 These charges need to balance.
Formulas Of Ionic Compounds
Formulas Of Ionic Compounds
 So, if magnesium wants to give away 2 electrons but
chlorine will only take 1, what do we need to take the
other electron from magnesium?
 Another chlorine atom.
 So 1 magnesium atom will bond with 2 chlorine atoms.
What is the resulting chemical formula?
 MgCl2
 This is called Magnesium Chloride and is a form of salt.
Naming Ionic Compounds
 For an ionic compound, the name of the positive
ion comes first and is followed by the name of the
negative ion. L.1.3.2.
 Ionic bonds most often occur between a metal and a
nonmetal. The metal becomes the positive ion because
it gives up electrons and the nonmetal becomes the
negative ion because it receives electrons.
 If the negative ion is an element, the ending changes to
–ide. Example: Magnesium Chloride.
Properties Of Ionic
Compounds
 In general, ionic compounds are
hard, brittle crystals and they
have high melting points. When
dissolved in solution, the ions
make good conductors of
electricity. L.1.3.3.
Ionic Crystals Pg. 26
High Melting Points
Electrical Conductivity
Storing Heat In Salt
Storing Heat In Salt