1) Ionic compounds form when a metal transfers electrons to a nonmetal, creating oppositely charged ions that are attracted to each other. This results in properties like being hard, brittle, and dissolving in water to conduct electricity. 2) Molecular compounds form when nonmetals share electrons in covalent bonds. Molecular compounds have more varied properties depending on the atoms involved. 3) The document provides instructions on drawing Lewis dot and Bohr-Rutherford diagrams to represent ionic and molecular compounds.

1. IONIC VS MOLECULAR
COMPOUNDS

2. INTRO TO IONIC COMPOUNDS
- Elements become stable by achieving 8 valence electrons (except for
hydrogen and helium, which achieve 2 electrons)
- Noble gases are non-reactive because they have 8 electrons
- This is called the Octet Rule
The number of valence
electrons can determine
reactivity:

3. INTRO TO IONIC COMPOUNDS
How many valence electrons
does each atom need to gain or
lose to achieve a full octet?
Alkali metals
lose 1
electron
Alkali earth
metals lose 2
electrons
Group 13
elements lose 3
electrons
Group 14 elements
lose or gain 4
electrons

4. INTRO TO IONIC COMPOUNDS
How many valence electrons
does each atom need to gain or
lose to achieve a full octet?
Group 14
elements lose or
gain 4 electrons
Group 15
elements gain
3 electrons
Group 16
elements gain
2 electrons
Halogens
gain 1
electron
Noble gases
already have
a full octet

5. INTRO TO IONIC COMPOUNDS
- Alkali metals have 1 electron in their valence
shell
- They can achieve a full octet by losing this
electron
- Thus they lose their valence electron easily to
another element, making them very reactive
Alkali metals
K
19P+
20N
Na
11P+
12N

6. INTRO TO IONIC COMPOUNDS
- Halogens have 7 valence electrons
- They can achieve a full octet by gaining one
electron
- Thus they readily take an electron from other
atoms, making them very reactive
Halogens
Cl
17P+
18N
F
9P+
10N

7. IONIC COMPOUNDS
Na
11P+
12N
Cl
17P+
18N
Forming an ionic bond:
1) An electron from Na is transferred to Cl
2) Na becomes a positive ion, Cl becomes a negative ion
3) Positive and negative ions attract, forming an ionic compound
+ -
Ionic bond = bond formed by the transfer of electron(s) from
metal to non-metal, making ions that attract each other

8. IONIC COMPOUNDS
Na
11P+
12N
Cl
17P+
18N
Drawing an ionic compound using a Bohr-Rutherford Diagram:
Example: NaCl

9. IONIC COMPOUNDS
Drawing an ionic compound using a Lewis Dot Diagram:
Example: NaCl
Na[ ]
+
Cl
..
:: ..[ ]
-
Rule: Square brackets must appear around ions

10. IONIC COMPOUNDS
Cl
17P+
18N
Drawing an ionic compound using a Bohr-Rutherford Diagram:
Example: AlCl3
Al
13P+
14N
Cl
17P+
18N
Cl
17P+
18N

11. IONIC COMPOUNDS
Drawing an ionic compound using a Lewis Dot Diagram:
Example: AlCl3
Al
.
.
.[ ]
3+
Cl
..
:: ..[ ]
-
Cl
..
:: ..[ ]
-
Cl
..
:: ..[ ]
-
Rule: Square brackets must appear around ions

12. PROPERTIES OF IONIC COMPOUNDS
Properties:
-Hard (ionic bond is strong)
-High boiling point (i.e. NaCl boils at 1413˚C)
-Brittle (shatters when hammered)
-Several ionic compounds dissolve in water
-Conducts electricity when dissolved

13. PROPERTIES OF IONIC COMPOUNDS
Several ionic compounds dissolve in water

14. Cl-
Na+
Cl-
Na+
Cl-
Na+
PROPERTIES OF IONIC COMPOUNDS
Several ionic compounds dissolve in water

15. NEGATIVELY-CHARGEDELECTRODE
POSITIVELY-CHARGEDELECTRODE
Na+
Cl-
Na+Cl-
Na+
Cl-
Na+
Cl-
- +
PROPERTIES OF IONIC COMPOUNDS
Several ionic compounds are also
electrolytes, which means they
dissolve to form a solution that
conducts electricity

16. MOLECULAR COMPOUNDS

17. MOLECULAR COMPOUNDS
Some elements share electrons to achieve a stable octet.
This allows a covalent bond to form between two elements.
O
8P+
8N
H
1P+
0N
H
1P+
0N
Covalent bond = bond formed by sharing of outer electrons
between non-metal atoms
Molecule = a particle in which atoms are joined by covalent bonds

18. MOLECULAR COMPOUNDS
F
9P+
10N
Drawing a molecular compound using a Bohr-Rutherford Diagram:
Example: HF
H
1P+
0N

19. MOLECULAR COMPOUNDS
Drawing a molecular compound using a Lewis Dot Diagram:
Example: HF
H:F
..
:..
Hydrogen fluoride is a diatomic molecule.
Diatomic molecule = Molecule consisting of only two atoms of
either the same or different elements

20. MOLECULAR COMPOUNDS
Some diatomic molecules consist of the same two elements:
i.e. O2
O :O
..
:
..
..
..
The following elements are diatomic when found in nature:
H2 O2 F2 Br2 I2 N2 Cl2

21. PROPERTIES OF MOLECULAR COMPOUNDS
Properties:
There are so many different molecular compounds that there are no
specific properties for them
H2 O2 F2 Br2 I2 N2 Cl2
gas gas gas liquid solid gas gas

22. HOMEWORK
Classify the following compounds as ionic or molecular. Then draw
the Bohr-Rutherford and Lewis Dot Diagram of each one:
a)Cl2
b)NH3
c)KCl
d)H2S
e)K2O