Valence Electrons
 Ions
 Cation
 Anion
 Ionization
energy
 Electronegativity
 Electrons
in the highest occupied energy
level
 The number of valence electrons determines
the chemical properties of an element
 To find the number of valence electrons of a
representative element, look at its group
number



Group 1A has 1 valence electron
Group 2A has 2 valence electrons
Group 8A has 8 valence electrons (He is an
exception)
 Lewis
structures
 Diagrams that show valence electrons as dots
 Don’t double up until you have a dot in each
quadrant (He exception)
 All of the elements within a group (except
He) have the same number of electron dots
in their structure
 Fill
in the following table with the correct
Lewis structures
Group
Period 1A
1
2
3
4
2A
3A
4A
5A
6A
7A
8A
 In
forming compounds, atoms want the
electron configuration of a noble gas.
 Octet=8
 Noble gases(except He) ns2np6 and have 8
electrons in their highest occupied energy
level
 Atoms of metals tend to lose their valence
electrons, leaving a complete octet in the
next-lowest energy level. Atoms of some
nonmetals tend to gain electrons or to share
electrons with another nonmetal to achieve a
complete octet.
 An
atom’s loss of valence electrons = cation:
positively charged ion.


Sodium atom, Na, forms a sodium cation, Na+
Calcium atom, Ca, forms a calcium cation, Ca2+
 Metals
 Na
1s22s22p63s1 Lose of valence electron Na+1s22s22p6
Which equals the configuration of Neon
 Na  Na+ + e-
 Anion
is an atom or group of atoms with a
negative charge
 The gain of electrons
 The name of the anion ends in –ide
 Chlorine atom forms a chloride ion and
oxygen atom forms an oxide ion
 Nonmetals
 Cl 1s22s22p63s2 3p5 gain of electron Cl- 1s22s22p63s2
3p6 which is equal to the configuration of Ar
 Cl
+ e-  Cl The ions formed from Group VII A are called
halide ions.


7 valence electrons and need to only gain 1
electron to achieve noble gas configuration
Charge of 1-
 How
many electrons will each element gain
or lose in forming an ion? Ca, F, Al, O
 Write
the name and symbol on the ion
formed when: potassium atom loses 1
electron, zinc atom loses two electron,
fluorine atom gains one electron
 Composed
of cations and anions
 Electrically neutral
 Held together by ionic bond: attraction
between positive cation and negative anion
 Chemical formula: shows kinds and numbers
of atoms (NaCl)
 Formula unit: lowest whole-number ratio of
ions in an ionic compound (Be2O2 = BeO)
 Crystalline
solid at room temperature
 High melting points
 Conduct an electric current when melted or
dissolved in water
 Monatomic
ion: single
 Polyatomic ions: composed of more than one


Names usually end in –ite or –ate
-ite has 1 less oxygen than -ate
 Charges
of the cations of transition metals
ions must be determined by the # electrons
lost.


Form more than one cation with different ionic
charges
Table 9.2 on page 255
 Cation
first, name doesn’t change
 Anion second, remove ending and add –ide
for monatomic anions
 For polyatomic ions use appropriate name
from list
 Valence
electrons of metal atoms are a sea
of electrons

Mobile and drift freely from one part of metal to
another
 Metallic
bond: attraction of free-floating
valence electrons for the positively charged
metal ions.


Good conductors of electric current because
electrons can flow freely in them
Malleable/ductile due to mobility of electrons
 Mixtures
composed of 2 or more elements, at
least one is a metal
 Properties are often superior to their
component elements