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Hemet High ● Chemistry
6 ● Chemical Bonding
Section 1: Introduction to Chemical Bonding
Chapter 6 Notes
Why do elements bond?

They want to become more ___________ elements, which they achieve by having
___ valence electrons, causing a ______________ in the atom’s potential energy.
Types of Chemical Bonding

When atoms bond, their _____________ electrons are moved around in a way to
make the atom more stable.

______________ Bonding: the electrical attraction between cations and anions.

______________ Bonding: the sharing of electrons between non-metals
Ionic or Covalent?

Looking at the difference in _____________________ of two elements will tell us
which bonding it will favor.

Electronegativity difference of _______ or less will favor ______________ and a
difference of ______ or more will favor ______________.
Types of Covalent

_____________-covalent: electrons are shared ________. Difference of 0.0 – 0.3

________-Covalent: electrons are _____ shared equally, one atom will have a
stronger pull on the electrons. Difference of 0.4 to 1.7. One atom will also take on a
slightly negative charge, while the other atom will take on a slightly positive charge.
Example

Use electronegativity differences to classify bonding between sulfur, and hydrogen,
cesium, and chlorine. Also state which atom is more negative.

Look at figure 20 on page 161 to find electronegativities.
o Sulfur and Hydrogen
o Sulfur and Cesium
o Sulfur and Chlorine
Section 2: Covalent Bonding and Molecular Compounds
Why Do Atoms Bond?
 To get _______ valence electrons

To become more _________

In ionic bonds, metals ________ electrons and non-metals _________ electrons.

What happens when both elements need electrons?
Molecules and Molecular Compounds

Compounds that are NOT held together by an ____________________________,
but instead by a ___________ of electrons.

Atoms held together by sharing electrons and filling the outer energy levels are joined
by a ________________.

________________ ONLY!!

A _____________ is a neutral group of atoms joined together covalent bonds. A
compound composed of molecules is called a ___________________________.

The chemical formula for a molecule is called the ________________________.

A ____________________________ tells you how many atoms of each element
one molecule of a compound contains.
Learning Check
Indicate whether a bond between the following would be ionic or covalent.
__________
A.
sodium and oxygen
__________
B.
nitrogen and oxygen
__________
C.
phosphorus and chlorine
__________
D.
calcium and sulfur
__________
E.
chlorine and bromine
Monatomic (One ________)

_________ gases are monatomic.

They exist as single atoms and do not combine with any other elements.

Ex: _______________________________________
7 Diatomic Molecules

Some elements will covalently bond to _____________ to form a molecule
composed of ______ atoms.

Some elements occur as “diatomic” molecules in nature because they are more
__________ than individual atoms

The 7 diatomic elements are all gases: _________________________________
Strength of Covalent Bonds

Distance between two bonding nuclei at the position of maximum attracting is
_________________

Bond length is determined by the ________ of the atoms and how many
___________________ are shared

________________ is the energy required to break a chemical bond and form
neutral isolated atoms.
Homework: Page 177 #1-3 and Page 209 #6, 10-11
Section 2 Notes, Continued
Octet Rule in Covalent Bonds

Remember that _________ compounds want to attain the electron configuration of
_____________________.

Hydrogen only needs ____, the rest need _____.

Regarding covalent bonds, electrons are ___________ between the atoms so that
they attain the electron configuration of noble gases.
Exceptions to the Octet Rule
–
A small group of molecules has an __________________________ and cannot
form an octet around each atom
Ex: NO2
–
–
Fewer than eight electrons: BORON is stable with 6!
Ex: BH3
–
–
Some central atoms have more than eight valence electrons
–
Referred to as an “___________” octet
–
Explained by d-orbitals
PCl5 (10 e-)
SF6 (12 e-)
Drawing Valence Electrons
“Electron-dot notation”:
Electrons are represented as dots located around the symbol
of the element. You must put one electron on each side before you double up.
Examples: Nitrogen =
Hydrogen =
Carbon =
In-Class Examples

Chlorine

Sulfur

Neon

Silicon

Magnesium
To draw Lewis structures for covalent bonds, use the NAS method:
 N (______________): Find the number of electrons needed to form full octets for all
elements involved. For most nonmetals, the number needed is 8. Hydrogen is the
exception, it needs only 2.

A (______________): Find the number of electrons available by adding up all of the
valence electrons for all elements involved.

S (______________): Subtract the two numbers. S= N-A

B (______________): A bond is formed with two electrons, so divide S by two to tell
you how many bonds to draw between the elements.

Draw the molecule. Put first atom in the center. H’s are always outside. Draw in the
bonds, then fill in the rest of the electrons.

Check to ensure all atoms have a full octet.
Draw the Lewis-dot-structure for the following molecules
1. HF
2. CCl2H2
Draw the Lewis-dot-structure for the following molecules
1. H2O
2. CO2
Types of Bonds
 Each bond involves the sharing of one pair of electrons.
Single Bonds= ___ e-’s
Double Bonds= ___ e-’s
Triple Bonds=___ e-’s
Resonance Structures
 Occurs when more than ___ valid Lewis Structure can be written for a molecule or ion

Differ only in the _________ of electron pairs, never the _______ positions

Actual molecule behaves as if it has ____ structure

Example: O3
Homework: 6.2 page 209 #15-19, 21, 23
Section 3: Ionic Bonding and Ionic Compounds
 Bond formed between ____ or more ions to form an electrically _________
compound by the ____________ of electrons.
 Formula Unit: the simplest collection of ________ from which an _________
compound’s formula can be established.
Ionic Bonding
How Ionic Bonding Works
The negative and positively-charged ions are attracted to each other (like a magnet).
Ionic bonding – only ____ types
1 Metal ion + 1 ___________ ion
or
1 Metal ion + 1 ___________ ion
Characteristics of Ionic and Covalent Compounds
Characteristic
Ionic Compound
Covalent Compound
Representative Unit
Bond Formation
Type of Elements
Physical State
Melting Point
Solubility in Water
Electrical Conductivity of
Aqueous Solution
Polyatomic Ions
 A charged group of ______________ bonded atoms.

They behave as one group.

If more than one is needed, written with __________________ around the ion.
Section 4: Bonding in Metals
Metallic bonds
 Bonds found in ________

Holds metal atoms together _______ strongly.

Formed between atoms of metallic elements

Good conductors at all states, ____________, very high ____________ points

The valence electrons of metal atoms can be modeled as a _______ of electrons.

Malleability and ______________
Crystalline Structure of Metals
 Metal atoms are arranged in very ____________ and _____________ patterns.

Resembles how _________ and ______________ are stacked in a grocery store.
Homework: 6.3 and 6.4 pg 210 #25-26, 28, 30-31