Transcript Ch.6 Chemical Bond Part 1

Unit 9
Chapter 6 – Chemical Bonds
Essential Questions
1) What is the difference between
compounds and mixtures?
2) Explain the difference between
an ion and molecule
3) Differentiate between an ionic/
covalent/ polyatomic
compound? Explain the role of
bonding in them.
4) What is the difference between
a binary compound and a
polyatomic compound?
5) What are the rules to be
followed when naming a
compound or writing its
formula?
• Some elements combine
chemically and no longer
have the same properties
they did before forming a
compound.
• Atoms form compounds
when the compound is
more stable than the
separate atoms.
Stability in Bonding
Noble gases are more
chemically stable than
other elements because they
have a complete outer energy
level.
Elements that do not have full
outer energy levels are
more stable in compounds.
• Atoms can lose, gain,
or share electrons to
get a stable outer
energy level.
• A chemical bond is
the force that holds
atoms together in a
compound.
Bonds
• Atoms bond when their
valence electrons interact.
• Remember – everyone
wants to be happy like the
noble gases.
Lewis Dot Diagrams
• Shows each valence
electron as a single dot.
Examples:
Fluorine
Carbon
Sodium
Connecting the dots
• You can show how the two
elements will combine using the
dots.
Cl
• There are three types of
atomic bonds:
–Ionic
–Covalent
–Metallic
I did not say
atomic bombs
Bonds
• ionic bonds
–Between a metal
and a non-metal.
– The metal loses it’s electrons
and the non-metal
takes the electron
from the metal.
Ionic Bonds
Bonds cont.
• covalent bonds
–Two non-metals
–The two nonmetals share
electrons.
bonds cont.
• metallic bonds – positively
charged metal ions are
surrounded by a cloud of
electrons, the outer energy level
held loosely so the electrons can
flow easily between the ions.
These metals conduct electricity
because the outer electrons can
easily move around.
Ionic Bonds
• When an atom gains or loses
an electron it becomes
charged (no longer neutral)
this is called ionization.
• An ion is a charged
atom.
• oppositely charged ions
–Metals become positively
charged when they give away
valence electrons
–Non-metals become
negatively charged when they
gain valence electrons.
Cation
• Positive ion
• Made when
an atom
loses an
electron.
Protons = 3
Electrons = 3
2
Anion
•Negative ion
•Made when
an atom gains
an electron.
Protons = 9
Electrons = 9
10
Covalent Bonds
• Formed between two nonmetals.
• Is the sharing of electrons
–Neither atom gives up
valence electrons, they
share them.
• Covalent bonds form
molecules.
• Atoms may share more than
one pair of electrons.
• Atoms do not always share
electrons equally.
Polar and non-polar molecules
Polyatomic Ions
• Compounds with both
ionic and covalent bonds.
• Acts the same as any
other ion.
Polyatomic Ions
• Examples:
–Ammonium
–Hydroxide
–Sulfate
NH4+
OHSO4+2
–Carbonate
CO3-2
Calcium Carbonate
CaCO3
Naming Binary Compounds