Chapter 2 - Atomic Structure and
Interatomic Bonding
There are four things to be covered:
• Basic atomic structure
• Electron configuration
• The periodic table
• Atomic and molecular bonding
Chapter 2 (continued)
Qualitative Questions
4 Explain the difference between a compound and a molecule.
5 Describe how and explain why atomic radius and electronegativity
change with position in the periodic table.
6 Describe the different kinds of primary atomic bonds and how each
type of primary atomic bond acts to fill the valence electron shells of
individual atoms.
7 How can you tell what kind of primary atomic bonding is present by
noting where the involved elements are located on the periodic
table?
1
Chapter 2 (continued)
Qualitative Questions (cont.)
8 Describe how the electronegativity difference affects the
ionic/covalent character of a bond.
9 Describe secondary atomic bonds including their cause and factors
affecting their strength.
10 Explain why some covalently-bonded molecules have low boiling
points and others have high boiling points.
11 Explain why covalent bonds are strong yet covalently-bonded
polymers are weak.
Chapter 2 (continued)
Basic Atomic Structure
•
•
•
•
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Chapter 2 (continued)
Basic definitions
•
atomic number - _____________ ______________________ .
•
atomic mass - the sum of the ____________ _____________
________________ .
•
isotopes - when atoms have the _________________ and
___________________. This is due to the number
of neutrons.
•
atomic weight - _________________ of the atomic masses of
an atom's natural isotopes
Chapter 2 (continued)
Electron Configuration
Bohr model
• Electrons can only _____________________________________
(ie. in discrete orbitals).
• An electron can move from one level to another, but it must “jump”
to the next level, either releasing or acquiring the proper amount of
energy.
3
Chapter 2 (continued)
Electron Configuration
Bohr model
wave-mechanical model
Chapter 2 (continued)
Electron Configuration (cont.)
Wave-Mechanical model
• Bohr model was unable to explain all electron behavior, therefore
this model was created.
• Created the idea of __________________________________.
Two electrons at each suborbital.
• suborbital
# at each primary level
total # electrons
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Chapter 2 (continued)
Electron Configuration (cont.)
• The electrons in the _____________ are termed the ____________
____________ .
• They are very important in _________________________ .
• This greatly affects physical properties such as _____________
__________________ .
Chapter 2 (continued)
Periodic Table (cont.)
• ________________________________________________
• ________________________________________________
• metals on the left, non-metals on the right
81 of 106 elements are classified as metals
• Electron configurations are based on energy minimization
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Chapter 2 (continued)
Periodic Table (cont.)
Chapter 2 (continued)
Periodic Table
(cont.)
• All elements in a group have the same _________________ in their
outermost shell. ____________________
ƒ Groups IA to 8A valence electrons are in the _______________
ƒ Group B valence electrons are in the ________________
• Elements within a group show many similarities in chemical
properties, and when they differ they do so in a systematic way.
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Chapter 2 (continued)
Trends in atomic properties - Atomic radius
• This is not a definite quantity. Taken as ½ the distance between
adjacent nuclei in a pure solid material.
• Generally radius ___________________________ in a group, and
____________________________ in a period.
ƒ As you move down the outer electrons are at a _____________
__________________. The nucleus pull is ____________, but
there is better _____________ from the nucleus.
ƒ Moving across, electrons are added at __________________
________. The stronger nucleus pull _____________________.
• (see inside front cover for atomic radii)
Chapter 2 (continued)
Trends in atomic properties - Atomic radius
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Chapter 2 (continued)
Trends in atomic properties – Electronegativity
_________________________________________________ .
•
Just an empirical number developed by Pauling
______________________
______________________
•
Generally electronegativity ______________________ in a group,
and ____________________________ in a period.
ƒ As you move down electrons added at a _______________
_______, therefore better shielding from the nucleus. There
is __________________ to fill the outer shell.
ƒ As you move across electrons added at _______________
________. The stronger nucleus pull, means the atoms
______________________________________.
Chapter 2 (continued)
Trends in atomic properties – Electronegativity
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Chapter 2 (continued)
Atomic and Molecular Bonding
Primary bonding categories
•
•
•
Secondary bonding categories
•
•
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Ionic bonds
• Forms between ________________________________________
___________ .
(ie. metals and non-metals)
• Electrons transfer from metals to non-metals producing _________
________. Both species are ______________________________ .
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Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Ionic bonds
• The bond is due to the ___________________________.
Fig 2.9
Ionic Bonding
must have some
sort of regular
pattern of ions
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Ionic bonds
• examples
ceramic materials, NaCl, MgCl, Ca(OH)2
• Be sure to use __________________ in calculations.
• ________ are usually much smaller than _________.
(front cover)
• The formation of an ionic bond is always ____________. Large
amounts of _________________________.
• Generally the __________________.
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Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Covalent bonds
• Bonding between atoms with ______________________________.
• Atoms share their _______________ so that both atoms achieve a
_____________________________.
• Atoms share __________________ .
• Polymers consist of long chains of _______________________ .
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Covalent bonds
Fig 2.10
Covalent Bonding
Actual geometry is
3-dimensional
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Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Covalent bonds
(cont.)
• Covalent bonds can be _____________________. This depends on
whether the electron distribution is ______________________ .
ƒ CH4
______________
__________
ƒ H 2O
________________
___________
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Covalent bonds
(cont.)
• A ________________________ actually lies somewhere between
an ionic bond and a pure covalent bond.
• There is a sharing of the electrons, but they favor the atom with
___________________________ .
• There is actually a ____________________ from purely ionic to
purely covalent
(Equation 2.10)
− 0.25( X A − X B ) ⎫
⎧
% ionic character = ⎨1 − e
⎬ *100
⎩
⎭
2
12
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Metallic Bonding
• In metals the atoms are packed in a ______________________ .
• The ______________ are only _______________ by their parent
nucleus and are attracted by the _____________________.
• No _________________________ as in covalent bonding.
• No ______________________ as in ionic bonding.
• We picture the _____________ (nucleus plus non-valence
electrons) surrounded by a __________________________.
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Metallic Bonding
Fig 2.11
Metallic Bonding
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Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Secondary Bonding
• The ____________ of one molecule is attracted to the ___________
of a neighboring molecule. This is called a ___________________.
• An _____________________________________. (see Table 2.3)
• Polymers are long chains containing _____________________. The
separate chains are held together by ____________________. This
accounts for their low melting point.
• Boiling is the __________________________________________.
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Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Secondary Bonding
Chapter 2 (continued)
Atomic and Molecular Bonding (cont.)
Secondary Bonding
(cont.)
• Hydrogen bonds - just a special type of ________________.
• Occurs in ____________________________________________.
• The electrons strongly favor F, N, or O and the ________________
_______________.
• Accounts for the unusual properties of water (high boiling point)
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Chapter 2 (continued)
Secondary Bonding
(cont.)
Fluctuating dipoles
• At any given instant the electrons in a symmetrical molecule might
be closer to one end than the other.
• This sets up a ____________________ that can affect neighboring
molecules.
• This very _______________ produces the ___________________
_________ in symmetric molecules, and _____________ in some
polymers.
Chapter 2 (continued)
Secondary Bonding
(cont.)
• Fluctuating dipoles
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Chapter 2 (continued)
Secondary Bonding
(cont.)
Element
Boiling Point
Helium
Neon
Argon
Krypton
Xenon
Radon
-269°C
-246°C
-186°C
-153°C
-107°C
-62°C
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