Chemical Bonding
Chemical Bonds:

Elements form bonds to be in a ___________ energy state
1. Ionic Bonds – _____________ of electrons, between ________ and _____________
2. Covalent Bonds – ___________ of electrons, between two nonmetals
3. Metallic Bonds- _______________ atoms in ___________ metals form bonds
Octet rule: atoms tend to ________, _______, or __________ electrons until they are surrounded by
___________ valence electrons to achieve a stable octet (noble gas configuration)
Electron Dot Symbols

______________ electrons: reside in the ____________ occupied energy level, reside in the outer s & p
orbitals and are the electrons involved in chemical ________________.

Electron-dot symbols are convenient way of showing the s & p electrons & tracking them in bond formation

-They consist of the chemical _____________ for the element plus a dot for ________ valence electron

Consider sulfur whose electron configuration is [Ne]3s23p4, thus there are
valence electrons.
S
Ionic Bonds –
•
Ionic compounds are ___________ due to the ______________ ____________ between unlike
charges organizing the ions of ionic substances into a rigid, organized three-dimensional
arrangement:
•
The ions are ____________together
•
Energy is ________________
•
Ions form solid _________________ structure
Lattice Energy
•
The ____________ required to separate completely a given quantity of a ___________ ionic
compound into its gaseous ions.
•
Thus, in reverse, the high _____________ is given off as heat and light when Na+ and Cl
incorporated into the NaCl salt _________________.
Steps in Ionic Bonding Process
-
is
•
Ionization Energy (IE) (Step 1):
•
The ________________ energy required to remove an _______________from the ground state of
an isolated gaseous atom or ion.
First Ionization Energy:
•
Na(g) + _______ → Na+ (g) +
______ ; +∆H (positive)
Second Ionization Energy:
•
Be(g) + ______ + _____ → Be2+ (g) + _______ ; +∆H (positive)
•
The greater the _______________ _______________, the more difficult it is to remove an e-.
Step 2 Ionic Bonding Process:
Electron Affinity (EA):
•
The energy
that occurs when an e- is added to a gaseous atom. For most atoms, the energy
_______________ when an e- is added.
•
Cl(g) + ______ → Cl- (g) + _____________ __________________
•
The ________________ the attraction between a given __________ and an added ____, the more
; -∆H (negative)
________________ the atom’s _____________ _______________. Halogens’ –s2p5 have the
___________ negative EA.
Step 3 Ionic Bonding Process:
•
Lattice Energy (LE)
•
•
Na+ + Cl- → _____________ + __________ ____________ ; -∆H (negative)
•
Properties of Ionic Compounds:
•
•
Arranged in repeating three-dimensional ________________
•
Large ________________ forces result in very _________________ structures
•
•
Ionic compounds can ____________ an electric current when melted or dissolved in water
•
Bonding in Metals
 Metallic bonds: _______________________________________________________
•
Bonding is due to ___________ _____________ which are _________________
throughout the entire solid
•
The metal is held ____________________ by the strong forces of ________________
between the positive _______________ and the delocalized ___________________.
Metals:
•
Metals are good _________________ of ________ and ________________because the
_______________ electrons are able to flow _____________
•
Valence electrons of metals can be thought of as a ______ of ___________ very
___________
•
Metallic Bonding - “Electron Sea”
Metallic Properties:
•
•
Have _________________________________________________________________
•
Luster = ___________
•
Ductile = ______________________________________________________
•
Malleable = ____________________________________________________
Properties can be explained by the ___________________ of electrons in metals
•
When subjected to pressure , the _____________ easily slide past each other like a ball
bearing immersed in oil.
Metallic Bonds
Bond Formation
Smallest Unit
Physical State at Room
Temperature
Melting Point
Solubility in Water
Electrical Conductivity
Other Properties
Covalent Bonding
What is a covalent bond?



A chemical bond that results from the ________________ of electrons, to form a stable ______
or __________ (Hydrogen only needs 2 to be stable)
Molecule = ______ or more atoms that are held together by _______________ bonds
Majority of covalent bonds form between _______________ (CLOSE together on periodic table)
Diatomic molecule




molecule containing the ______ _____ atoms
Some elements _________ exist this way because they are _____ stable than the individual atoms
The Seven Diatomic Elements :___________________________________
Bonds in _____ the ________________ ions and diatomics are all covalent bonds
Single Covalent Bonds

Two atoms held together by a sharing of _____ pair of
electrons are joined together by a single covalent bond.

An electron dot structure represents the __________
pair of electrons of the covalent bond by ______ dots.

A ______________ formula represents the covalent bonds by _________ and shows the arrangement
of covalently bonded atoms.

A pair of valence electrons that is ____ ___________ between atoms is called an unshared pair, also
known as a ______ pair of a _________________ pair.
Double & Triple Covalent Bonds
o
Atoms form _______ or ____________ covalent bonds if they can attain a noble gas structure by
sharing two or three pairs of electrons.
o
A double bond involves _________ ________ pairs of electrons.
o
A __________ bond involves sharing ___________ pairs of electrons
Bond Length

From a study of various Nitrogen containing compounds ______ _____________ as a function of bond
type can be summarized as follows:
N-N 147pm
N=N 124pm
N≡N 110pm
-

As a general rule, the _________ e that are shared:

the __________ the covalent bond (N≡N > O=O > F–F)

the _____________ the covalent bond (N≡N < O=O < F–F)
Single
Double
Triple
Covalent Nomenclature
•
1.
Prefix System (binary molecules)
Add prefixes to indicate # of atoms. Omit mono- prefix on first element.
1. Change the ending of the
second element to -ide.
2. Second element ALWAYS gets a prefix.
Prefixes:
1- _______________________
2- _______________________
3- _______________________
4- _______________________
5- _______________________
6- _______________________
7- _______________________
8- _______________________
9- _______________________
10__________________
Examples:
•
CCl4 _______________________
•
arsenic trichloride _______________
•
N2O _______________________
•
dinitrogen pentoxide _____________
•
SF6 _______________________
•
tetraphosphorus decoxide __________
Lewis Diagrams
1. Arrange atoms
•
___________ atom is usually in the center (often Carbon)
•
If not Carbon, _______________ electronegative atom is in center
•
Hydrogen is always _____________ (on the side, not a central atom)
2. Find ___________ # of e- available to bond (_____________ e-! only )
3. Place a __________ of electrons between _____________ atom and each terminal atom
4. Place remaining electrons in pairs around _____________ atoms (except H) to satisfy octet rule
•
Any ______________ pairs are assigned to central atom
5. Determine whether or not central atom satisfies _____________
•
If not, __________ one or more lone pairs from terminal atoms to double or triple bonds
•
Certain atoms can be ___________ to octet rule – H, Be, B, S, P, Xe
Ex 1 : CF4
Ex 2: CO2
Polyatomic Ions:

To find ___________ # of valence e-:

_________ 1e- for each negative charge

____________ 1e- for each positive charge

Place ______________ around the ion and label the charge
Ex 3: ClO4-1
Octet Rule Exceptions:

______________  2 valence e-

Boron & Beryllium get ____ & ____ valence e- respectively

_____________ octet  more than 8 valence e- (e.g. S, P, Xe)
Ex 4: BeCl2
Ex 5: SF6
Resonance Structures

Molecules that ____ be correctly represented by a _________ Lewis diagram

Actual structure is an _____________ of all the possibilities

Show all possible structures separated by double-headed ___________
Ex: SO3
Bond Polarity

Most bonds are a blend of ________ & __________ characteristics.

____________ in electronegativity determines bond type.

Electronegativity
o ______________ an atom has for a shared pair of electrons.
o
___________ e-neg atom  -
o ___________ e-neg atom +
Electronegativity Difference
 If the difference in electronegativities is between:
 1.7 to 4.0: ___________
 Greater than 0.3 & less
than 1.7: _____ Covalent

0 to 0.3: __________
________________
The type of bond can usually be calculated by finding the difference in electronegativity of the two atoms
that are bonded.
o
o
o
Compound:
Difference:
Type of Bond:
F2 or F-F
_______
_______
CF4
_______
_______
LiF or Li - F
_______
_______
o
o
o
Nonpolar Covalent Bond
e- are shared _____________
________________ e- ______________
usually _____________ atoms
 Ex: H2 or Cl2
o
o
o
Polar Covalent Bond
e- are shared ________________
_____________ e- density
results in ________ ___________ (dipole)
 Ex: H2O
VSPER Theory
o
o
________________________________________________________
Electron pairs ____________ themselves in order to _______________ repulsive forces
Types of e- Pairs
o __________________ – form bonds
o Lone pairs – _______________ eo Total e- pairs– _________ + _______ pairs
 Lone pairs ________ more ____________ than bonding pairs!!!
 Lone pairs __________ the bond angle between atoms
Determining Molecular Shape
o
o
o
o
Draw the ____________ Diagram
Tally up e- pairs on central atom (bonds + lone pairs)
double/triple bonds = ONE pair
Shape is determined by the _________ of bonding pairs and lone pairs
Common Molecular Shapes:
Ex: BeH2
Ex: BF3
Molecular Polarity:
 ___________ molecule = one end slightly __________ and one end slightly __________
 Molecule with 2 poles = ___________ molecule or ___________
 _____________, symmetry and bond polarity determines molecular polarity
 H – O bond is __________ and water is ______________, so H2O is polar
 C – Cl bond is polar, but CCl4 is _________________, so molecule is _____________
Identify each molecule as polar or nonpolar
o
o
O2 : Nonpolar Bonds __________
CS2 : Linear  ______________
o
o
CF4 : Tetrahedral  __________
H2O : Bent  _______________