Ionic compounds form when ions bond through electrostatic attraction. Metals form cations by losing electrons to achieve a full outer shell, while nonmetals form anions by gaining electrons. Cations and anions are attracted due to their opposite charges. Ionic compounds have high melting points, are crystalline solids, and dissolve in water due to the separation of ions. They do not conduct electricity as solids but do so as liquids or dissolved solutions.

1. IONIC COMPOUNDS
NKCSD
Formation and Properties of Ionic Compounds
Why do ionic bonds form?
How are ionic compounds formed?
What are the properties of ionic compounds?
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2. Recall:
• Elements are the simplest of substances that cannot
be broken down further by chemical or physical
means.
• Each element is made up of just one particular type
of atom, which is different from the atoms in any
other element.
• Atoms consist of three types of subatomic particles:
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3. Recall:
• An important feature of subatomic particles is their
electrical charge:
• In atoms, the number of positive protons equal
the number of negative electrons.
• For example: Fluorine
3
9 protons
9 electrons
________
0
= 9+
= 9-

4. Chemical Bonds:
• Valence electrons are the electrons in an atom’s
outermost energy level that determine the
chemical properties of an element. It is valence
electrons that are responsible for holding two or
more atoms together in a chemical bond.
• Bonding occurs because atoms with incomplete
outer energy levels are unstable. By forming
bonds, atoms completely fill their outer energy
levels and become stable (the octet rule).
• The octet rule states that atoms lose, gain, or
share electrons in order to acquire a full set of
eight valence electrons (the stable electron
configuration of a noble gas).
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5. 5

6. Bond, Ionic Bond
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7. Ionic Bonds
Ionic bonds form when electrons are
transferred from metals to nonmetals
(atoms will gain or lose electrons in an
effort to acquire a full set of 8 valence
electrons).
• When electrons are transferred, atoms become
ions (specifically, cations and anions).
• Unlike atoms, ions have an electrical charge
because they contain an unequal number of
protons and electrons.
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8. Forming Ions
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9. Forming Ions
• Formation of Cations
• Cations are positively charged ions; they are formed
when an atom (usually a metal) loses valence
electrons.
• Atoms that lose electrons have more protons than
electrons and so have an overall positive charge
(and are smaller in size than the original atom).
• The charge of cations is given by the number of
electrons lost, followed by a “+” symbol (ex. 2+).
• The formula of cations is given by the chemical
symbol followed by the charge (ex. Mg2+).
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10. Forming Ions
• Cation Ionic Charges
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Group Gain/Loss of e- Charge Formula
Group 1A - Na Lose 1 1+ Na1+
Group 2A - Mg Lose 2 2+ Mg2+
Group 3A - Al Lose 3 3+ Al3+

11. Forming Ions
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12. Forming Ions
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1+
Sodium Atom, Na
11 protons
11 electrons
________
0
11 protons
10 electrons
________
1+
Sodium Ion, Na1+
= 11+
= 11-
= 11+
= 10-

13. Forming Ions
13
2+
Magnesium Atom, Mg
12 protons
12 electrons
________
0
12 protons
10 electrons
________
2+
Magnesium Ion, Mg2+
= 12+
= 12-
= 12+
= 10-

14. 14

15. Concept Check
Draw the electron-dot structures for the following atoms
and their respective ions:
• sodium
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16. Forming Ions
• Formation of Anions
• Anions are negatively charged ions; they are formed
when an atom (usually a nonmetal) gains valence
electrons.
• Atoms that gain electrons have less protons than
electrons and so have an overall negative charge
(and are larger in size than the original atom).
• The charge of anions is given by the number of
electrons gained, followed by a “-” symbol (ex. 2-).
• The formula of anions is given by the chemical
symbol followed by the charge (ex. S2-).
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17. Forming Ions
• Anion Ionic Charges
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Group Gain/Loss of e- Charge Formula
Group 5A - N Gain 3 3- N3-
Group 6A - S Gain 2 2- S2-
Group 7A - F Gain 1 1- F1-

18. Forming Ions
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1-
Fluorine Atom, F
9 protons
9 electrons
________
0
9 protons
10 electrons
________
1-
Fluoride Ion, F1-
= 9+
= 9-
= 9+
= 10-

19. Forming Ions
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2-
Sulfur Atom, S
16 protons
16 electrons
________
0
16 protons
18 electrons
________
2-
Sulfide Ion, S2-
= 16+
= 16-
= 16+
= 18-

20. Concept Check
Draw the electron-dot structures for the following atoms
and their respective ions:
• fluorine
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21. ADD CHARGES TO PERIODIC TABLE
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1+
2+ 3+ 4+/- 1-2-3-

22. Ionic Compounds
• Ionic Compounds
• Remember, ions are formed when neutral atoms
gain/lose electrons to achieve stability. The
positively charged cation is attracted to the
negatively charged anion, and an ionic bond is
formed between them. This is a fairly strong
attraction.
• Compounds that contain ions are called ionic
compounds and result when metals (cations)
react with nonmetals (anions). Ionic compounds
are neutral, therefore the number of positive
charges must equal the number of negative
charges.
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23. Ionic Compound Formation
Sodium Chloride Formation
Sodium chloride is an ionic compound formed by the
reaction between the metal sodium and the nonmetal
chlorine.
Na + Cl  NaCl
The positive sodium ions and the negative chloride ions are
strongly attracted to each other and form an ionic bond.
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24. Ionic Compound Formation
Magnesium Oxide Formation
Magnesium oxide is an ionic compound formed by the
reaction between magnesium and oxygen.
Mg + O  MgO
The positive magnesium ions and the negative oxide ions are
strongly attracted to each other and form an ionic bond.
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25. Ionic Compound Formation
• Sodium chloride and magnesium oxide are simple
ionic compounds. In each case, the metal and
nonmetal need to lose and gain the same number
of electrons.
• BUT…This is not always the case.
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26. Ionic Compound Formation
• Sodium Oxide Formation
• Sodium needs to lose 1 electron but oxygen needs to gain
2 electrons. Therefore, 2 sodium atoms are required for
each oxygen atom.
• Magnesium Chloride Formation
• Magnesium needs to lose 2 electrons but chlorine only
needs to gain 1 electron. Therefore, 2 chlorine atoms are
required for each magnesium atom.
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27. Ionic Compound Properties
1. Most ionic compounds are crystalline solids at
room temperature.
2. Ionic compounds are hard, rigid and brittle – they
shatter when they are hit.
3. Ionic compounds have high melting and boiling
points.
4. Ionic compounds are usually soluble (can
dissolve) in water.
5. Ionic compounds do not conduct electricity when
they are solid because the ions are packed
together and cannot move. They can, however,
conduct as liquids because the charged ions in
the dissolved state are free to move (electrolytes).
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28. Ionic Compound Properties
• Structure:
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