IONIC AND METALLIC BONDING CH 7
I. Valence Electrons
Electrons in the highest occupied energy level of an element’s atoms
To find the number of valence electrons in an atom of a representative element, simply look at its group number. If it’s in group 1 or 2. If it is in groups 13-18 subtract 10 to find the number of valence electrons.
II. Octet Rule
In the formation of compounds, atoms tend to achieve the electron configuration of a noble gas.
Atoms either gain, lose, or share electrons to form compounds.
III. Cations
Loses an e-
-An atom’s loss of valence electrons produces a cation, or a positively charged ion.
III. Cations Metals – lose valence e- easily Transition metals – have 2 valence e-, usually
lose those two to form 2+ ions, but can also lose d electrons to form other ions
IV. Anions
Nonmetals easily gain e- to form negative ions to get to 8 valence e-
Gains an e-
Chloride ion
V. Ionic Bonds
When oppositely charged ions attract, electrostatic force that holds them together = ionic bond
Compounds containing ionic bonds = ionic compounds
Electrons are transferred from cations to anions
Bonds formed between metals and nonmetals (or contain a polyatomic ion)
V. Ionic Bonds
Na·
1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 3p5
RESULTS IN
Na+
1s2 2s2 2p6 1s2 2s2 2p6 3s2 3p6
VI. Properties of Ionic Compounds
Most ionic compounds are crystalline solids at room temperature. Arranged in repeating three-dimensional
patterns Ionic compounds generally have high
melting points Large attractive forces result in very stable
structures
VI. Properties of Ionic Compounds
Ionic compounds can conduct an electric current when melted or dissolved in water. When ionic compounds are dissolved in water
the crystalline structure breaks down. This allows the ions to move freely which results in conductivity.
VII. Metallic Properties
Metals are good conductors because the valence electrons are able to flow freely within them. Valence electrons of metals can be thought of
as a sea of electrons.
VII. Metallic Properties
The ductility and malleability of metals can be explained by the mobility of electrons in metals. When a metal is subjected to pressure , the
cations easily slide past each other like a ball bearing immersed in oil. If an ionic crystal is stuck with a hammer the cations are pushed together, repel, and the crystal shatters.