.............BondTypes&Properties.ppt.......

bonding

1. Bellwork
1.Name the 3 main types of
chemicals bonds that
elements form.
2.How are the electrons in
these types of bonds
different?
3.Give an example of each
type of bond.
Homework
Complete
WS 4.2

2. Types of Chemical Bonds
•Three basic types of
bonds:
1.Ionic
•Electrostatic attraction
between ions
•Electrons are transferred
2.Covalent
•Sharing of electrons
3.Metallic
•Metal atoms bonded to
several other atoms
•Electrons are delocalized
(free to move throughout
the structure).

4. Ionic Bonds
•Formed between atoms of metals and nonmetals
with very different electronegativity values.
•Formed by the transfer of electrons (from the
metal to the nonmetal).
•Produces charged ions which form a salt.
•Have high melting & boiling points due to strong
attraction between ions.
•Ionic solids are insulators; they must be melted or
put in solution in order to conduct.
•Brittle
•Examples: NaCl, CaCl
2
, K
2
O

5. Ionic compounds exist as crystal lattice structures with
particular patterns of alternating positive and negative ions.
Ionic compounds are called salts.
NaCl forms a cubic
crystal lattice structure.

6. Solid ionic
compound
Molten ionic
compound
Ionic
compound
dissolved in
water

7. Covalent Bonds
•Formed between nonmetallic
elements
•Formed when two atoms share one or
more pairs of outer-shell electrons.
•Forms stable non-ionizing particles;
they are not conductors at any state.
•Examples: O
2, CO
2, C
2H
6, H
2O, SiC

8. Covalent compounds are called molecules.
•A group of atoms held together by covalent
bonds is called a molecule.
•Diatomic elements are also molecules.

9. Molecules vs. Salts

10. Properties of Molecular
Covalent Compounds
•Lower Melting Points than Ionic Compounds (which
means that their attractions (IMFs) are typically weaker
than ionic bonds)
Liquids or gases at room temperature

11. Network solids are substances that consist of atoms bonded
covalently in a continuous two- or three-dimensional array.
There is no natural beginning or end to the chains of atoms.
Covalent Network Solids
Silicon dioxide, SiO
2
, exists
as a network solid that is
represented as (SiO
2)
n.
Other examples that you
should be aware of are
graphite and diamond, which
are both allotropes of carbon.

13. Metallic Bonds
•Formed between atoms of
metallic elements.
•Ve- form an electron cloud
around metal cations.
•Good conductors at all states,
lustrous, very high melting points.
•Examples; Na, Fe, Al, Au, Co

14. "Sea" of Electrons in Metallic Bonding
Ve- of metal atoms move freely among the ions,
forming a “sea” of delocalized electrons that hold
the metal cations rigidly in place.

15. Metals Form Alloys
•Metals do not chemically combine with
metals.
•They form an alloy; a solution of a metal in a
metal.
•Examples: steel, brass, bronze and pewter.

16. Summary
Network
Covalent
Molecular
Covalent