Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
5.1 : BONDING
Atoms are rarely found in their elemental form but are usually found bonded
to other atoms as part of compounds. A bond is composed of a group of
negatively charged valence electrons between the atoms that
simultaneously attract the positively charged nuclei of both atoms. Since the
two atom nuclei are attracted to the same group of electrons, they remain
together. Atoms bond because are more stable together. They are more
stable together because energy is released in the bond-forming exothermic
reaction. Bonds are of two types that differ in the way the valence electrons
involved are arranged.
Ionic Bonding
One type of bond is called an ionic bond because the bond is formed
between oppositely charged ions. This type of bond is said to be formed
by electron transfer (simultaneous loss and gain of electrons to form
ions). Ions are charged particles formed by an atom either losing one or
more electrons to form a positively charged ion (called a cation because
it is attracted to the negatively charged pole (cathode) of an electric
field) or by an atom gaining one or more electrons to form a
negatively charged ion (called an anion because it is attracted to the
positively charged pole (anode) of an electric field). These ions are usually
formed by atoms transferring electrons during chemical reactions to form
oppositely charged ions that attract one another (an ionic bond). Several
examples of ions and their formation are shown below:
2 Na + Cl2 → 2 Na+ + 2 Cl-
2 Ca + O2 → 2 Ca+2 + 2 O-2
2 K + S → 2 K+ +
S-2 Al + N → Al+3
+ N-3
The charge on an ion is determined by how many electrons are lost or
gained and whether the atom loses electrons (metal atoms, because of their
lower electronegativity, tend to lose electrons forming positive ions) or gains
electrons (nonmetal atoms, because of their higher electronegativity, tend to
gain electrons forming negative ions). The number of electrons lost or
gained is determined by the octet rule, which states that atoms tend to
gain or lose (or share) electrons so as to achieve eight electrons in their
outer shell. This is the same electron arrangement as that of the most stable
atoms in the periodic table, the group VIII, inert gas atoms. Metals will tend
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
,Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
to lose all of their outer shell electrons to uncover an inner shell that has eight
electrons, and nonmetals will tend to gain enough electrons to complete an
outer shell of eight. That is why, in the above examples:
• Sodium loses its one outer shell electron to form a Na+ ion.
• Calcium loses its two outer shell electrons to form a Ca+2 ion.
• Aluminum loses its three outer shell electrons to form an Al+3 ion.
• Chlorine gains one electron into its outer shell of seven to form a Cl- ion.
• Oxygen gains two electrons into its outer shell of six to form an O-2 ion.
• Nitrogen gains three electrons into its outer shell of five electrons to form a
N-3 ion.
Formation of Inert Gas (Octet) Electron Structure in Ions
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
,Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
(valence shell shown in red)
(by loss of 1
Na11 = 1s2 2s2 2p6 3s1 → Na +
= 1s2 2s2 2p6
electron)
(by loss of 3
Al13 = 1s2 2s2 2p6 3s2 3p1 → Al +3 = 1s2 2s2 2p6
electrons)
Ca20 = Ca20+2 = (by loss of
1s2 2s2 2p6 3s2 3p6 →
1s2 2s2 2p6 3s2 2
4s2 3p6 electrons)
(by gain of 2
O = 1s2 2s2 2p4 → O -2
= 1s2 2s2 2p6
8 electrons)
S16 = 1s2 2s2 2p6 3s2 3p4 (by gain of
S16 -2 =
→ 2
1s2 2s2 2p6 3s2
3p6 electrons)
(by gain of 3
N7 = 1s2 2s2 2p3 → N -3 = 1s2 2s2 2p6
7
electrons)
Ions (and ionic bonds holding these ions together in ionic compounds) tend
to form when a metal (an element with low electronegativity, meaning low
attraction for electrons) undergoes a chemical reaction with a nonmetal (an
element with high electronegativity, meaning high attraction for electrons).
These ionic compounds have relatively high melting points and boiling points
and are very hard and brittle crystalline solids. The high melting point,
boiling point, and hardness are due to the very strong ionic bonds holding
the component ions together. These ions are arranged in an orderly crystal
lattice and movement of one plane of ions causes the layers to fracture
accounting for the brittleness of the compounds. These compounds do not
conduct an electric current in the solid state since the ions cannot move
under these conditions, but solutions of or molten ionic compounds readily
conduct electricity since the ions separate from one another under these
conditions.
Module 5 Problem Set 1
What will be the charge of the ion formed from each of these atoms? Si14,
As33, Mg12, Rb37, F9, Ge32, Sn50
ION CHARGE
Si14 = 1s2, 2s2,2p6, 3s2, 3p2 ⟶ Si1 +4
= 1s2, 2s2,2p6 (by loss of 4 electrons)
4
Si14 (nonmetal = gain electrons) 1s2 2s2 2p6 3s2 3p2
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
, Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
gain 4 → Si-4
As33 = 1s2, 2s2,2p6, 3s2, 3p6, 4s2, 3d10, 4d3 ⟶ As
3
+5
= 1s2, 2s2,2p6, 3s2, 3p6, 3d10, (by
3
loss
of 5 electrons)
As33 (nonmetal = gain electrons) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 gain
3 → As-3
Mg12 = 1s2, 2s2,2p6, 3s2
Mg12 (metal = lose electrons) 1s2 2s2 2p6 3s2
lose 2 → Mg+2
Rb37, (metal = lose electrons) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 lose
1 → Rb+1
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
latest update 2021/2022 graded A+
5.1 : BONDING
Atoms are rarely found in their elemental form but are usually found bonded
to other atoms as part of compounds. A bond is composed of a group of
negatively charged valence electrons between the atoms that
simultaneously attract the positively charged nuclei of both atoms. Since the
two atom nuclei are attracted to the same group of electrons, they remain
together. Atoms bond because are more stable together. They are more
stable together because energy is released in the bond-forming exothermic
reaction. Bonds are of two types that differ in the way the valence electrons
involved are arranged.
Ionic Bonding
One type of bond is called an ionic bond because the bond is formed
between oppositely charged ions. This type of bond is said to be formed
by electron transfer (simultaneous loss and gain of electrons to form
ions). Ions are charged particles formed by an atom either losing one or
more electrons to form a positively charged ion (called a cation because
it is attracted to the negatively charged pole (cathode) of an electric
field) or by an atom gaining one or more electrons to form a
negatively charged ion (called an anion because it is attracted to the
positively charged pole (anode) of an electric field). These ions are usually
formed by atoms transferring electrons during chemical reactions to form
oppositely charged ions that attract one another (an ionic bond). Several
examples of ions and their formation are shown below:
2 Na + Cl2 → 2 Na+ + 2 Cl-
2 Ca + O2 → 2 Ca+2 + 2 O-2
2 K + S → 2 K+ +
S-2 Al + N → Al+3
+ N-3
The charge on an ion is determined by how many electrons are lost or
gained and whether the atom loses electrons (metal atoms, because of their
lower electronegativity, tend to lose electrons forming positive ions) or gains
electrons (nonmetal atoms, because of their higher electronegativity, tend to
gain electrons forming negative ions). The number of electrons lost or
gained is determined by the octet rule, which states that atoms tend to
gain or lose (or share) electrons so as to achieve eight electrons in their
outer shell. This is the same electron arrangement as that of the most stable
atoms in the periodic table, the group VIII, inert gas atoms. Metals will tend
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
,Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
to lose all of their outer shell electrons to uncover an inner shell that has eight
electrons, and nonmetals will tend to gain enough electrons to complete an
outer shell of eight. That is why, in the above examples:
• Sodium loses its one outer shell electron to form a Na+ ion.
• Calcium loses its two outer shell electrons to form a Ca+2 ion.
• Aluminum loses its three outer shell electrons to form an Al+3 ion.
• Chlorine gains one electron into its outer shell of seven to form a Cl- ion.
• Oxygen gains two electrons into its outer shell of six to form an O-2 ion.
• Nitrogen gains three electrons into its outer shell of five electrons to form a
N-3 ion.
Formation of Inert Gas (Octet) Electron Structure in Ions
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
,Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
(valence shell shown in red)
(by loss of 1
Na11 = 1s2 2s2 2p6 3s1 → Na +
= 1s2 2s2 2p6
electron)
(by loss of 3
Al13 = 1s2 2s2 2p6 3s2 3p1 → Al +3 = 1s2 2s2 2p6
electrons)
Ca20 = Ca20+2 = (by loss of
1s2 2s2 2p6 3s2 3p6 →
1s2 2s2 2p6 3s2 2
4s2 3p6 electrons)
(by gain of 2
O = 1s2 2s2 2p4 → O -2
= 1s2 2s2 2p6
8 electrons)
S16 = 1s2 2s2 2p6 3s2 3p4 (by gain of
S16 -2 =
→ 2
1s2 2s2 2p6 3s2
3p6 electrons)
(by gain of 3
N7 = 1s2 2s2 2p3 → N -3 = 1s2 2s2 2p6
7
electrons)
Ions (and ionic bonds holding these ions together in ionic compounds) tend
to form when a metal (an element with low electronegativity, meaning low
attraction for electrons) undergoes a chemical reaction with a nonmetal (an
element with high electronegativity, meaning high attraction for electrons).
These ionic compounds have relatively high melting points and boiling points
and are very hard and brittle crystalline solids. The high melting point,
boiling point, and hardness are due to the very strong ionic bonds holding
the component ions together. These ions are arranged in an orderly crystal
lattice and movement of one plane of ions causes the layers to fracture
accounting for the brittleness of the compounds. These compounds do not
conduct an electric current in the solid state since the ions cannot move
under these conditions, but solutions of or molten ionic compounds readily
conduct electricity since the ions separate from one another under these
conditions.
Module 5 Problem Set 1
What will be the charge of the ion formed from each of these atoms? Si14,
As33, Mg12, Rb37, F9, Ge32, Sn50
ION CHARGE
Si14 = 1s2, 2s2,2p6, 3s2, 3p2 ⟶ Si1 +4
= 1s2, 2s2,2p6 (by loss of 4 electrons)
4
Si14 (nonmetal = gain electrons) 1s2 2s2 2p6 3s2 3p2
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
, Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
gain 4 → Si-4
As33 = 1s2, 2s2,2p6, 3s2, 3p6, 4s2, 3d10, 4d3 ⟶ As
3
+5
= 1s2, 2s2,2p6, 3s2, 3p6, 3d10, (by
3
loss
of 5 electrons)
As33 (nonmetal = gain electrons) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 gain
3 → As-3
Mg12 = 1s2, 2s2,2p6, 3s2
Mg12 (metal = lose electrons) 1s2 2s2 2p6 3s2
lose 2 → Mg+2
Rb37, (metal = lose electrons) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 lose
1 → Rb+1
Portage LearningCHEM 103module 5 notes and problem sets
latest update 2021/2022 graded A+
