Prescriptive Activities: Facet Cluster 1.6: PF#50-53
Teacher Page
Prescriptive #50-53:
50 The student does not use the periodic table accurately to predict bonding
behavior.
51 The student predicts that nonmetals form ionic bonds.
52 The student predicts that a metal and a nonmetal form covalent bonds. (sharing
electrons).
53 The student confuses metallic bonds with ionic bonds.
Materials:
Student handout
Internet Access
Background:
In understanding and applying chemical principles it is important to be able to distinguish
between different categories of elements and compounds which are based on the types of
bonds between neighboring atoms. The three categories of bonding that you will
differentiate between in this activity include ionic, covalent and metallic bonds.
You must first, however, know how to identify metals and nonmetals on the periodic table.
1
Prescriptive Activities: Facet Cluster 1.6: PF#50-53
Teacher Page
Covalent bonding
When two or more nonmetal atoms bond together they share electrons forming a
covalent bond. They do this so that each atom will attain a noble gas electron configuration
with 8 electrons in its outermost shell (except for hydrogen which will have two electrons in
its outermost shell).
Examples: In hydrogen bromide (HBr), the two atoms share an electron from
H Br
hydrogen and an electron from bromine. Bromine now has 8 valence
electrons around it and the hydrogen atom has two electrons to fill its
outermost energy level.
In PCl3, valence electrons are shared such that all 4 atoms have 8 valence
electrons. There are a few molecules with beryllium (Be) and boron (B) that
are exceptions to the octet rule and will have fewer than 8 electrons around the central
atom.
Ionic bonding
When a metal atom and a nonmetal atom bond together, the nonmetal atom removes the
valence electrons from the metal atom, thereby becoming a negatively charged ion
containing more electrons than protons. (Notice that the Cl- ion is larger than the Cl atom.
This is because there is more electron repulsion due to the extra electron. It is important to
realize that the added electron is in the same energy level as the other valence
electrons). The metal atom is now a positively charged ion because it has fewer electrons
than protons. (Notice that the Na+ ion is much smaller than the Na atom. It has one less
energy level). The transfer of electrons results in two oppositely charged ions that are now
held together by
their mutual
electrostatic
attraction, thus
forming an ionic
bond. Ionic crystals
exist as huge
numbers of these
ions attracted to
each other, forming a
regular lattice
structure.
2
Prescriptive Activities: Facet Cluster 1.6: PF#50-53
Teacher Page
Metallic bonding
Metal atoms are held together by the electrostatic attraction between free mobile outer
electrons moving within a lattice of positively charged metal ions containing the nuclei
and inner electrons of each metal atom. The metal ions exist in layers which can slide over
each other as the metal is bent or hammered.
Directions of Activity:
Watch the video at this link.
Video distinguishing between ionic and covalent bonding:
Ionic and covalent bonding animation (1:56)
http://www.youtube.com/watch?v=QqjcCvzWwww&feature=player_detailpage
Video of metallic bonding (1:54):
Chemical Bonding and Atomic Structure (2nd Ed.) (clip)
http://www.youtube.com/watch?v=ijw8OBt4btM&feature=player_detailpage
Questions:
1. Give an example of two atoms that would form ionic bonds.
2. Give an example of two atoms that would bond covalently.
3. What are two properties of an ionic compound that result from an ionic bond?
4. What are two properties of a metallic compound that result from metallic bonds?
3
Prescriptive Activities: Facet Cluster 1.6: PF#50-53
Teacher Page
References
Video distinguishing between ionic and covalent bonding: Ionic and covalent bonding animation
(1:56) http://www.youtube.com/watch?v=QqjcCvzWwww&feature=player_detailpage
Video of metallic bonding: Chemical Bonding and Atomic Structure (2nd Ed.) (clip) (1:54):
http://www.youtube.com/watch?v=ijw8OBt4btM&feature=player_detailpage
Ionic bond Image from:
http://wps.prenhall.com/wps/media/objects/165/169289/blb9ch0207.html
Metallic bond Image from:
http://www.bbc.co.uk/scotland/learning/bitesize/higher/chemistry/energy/bsp_rev1.shtml
Periodic Table Image from:
http://andromeda.rutgers.edu/~huskey/images/periodic_table_color1_1024x768_w.png
Teacher Notes:
This activity is best viewed on the computer because the colors show up better on the screen than
in print.
4