Compounds and Bonds

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Compounds and Bonds
Chapter 2 - Chemical Interaction
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Warm up Define the following terms on the front
of your compounds packet
Compound
Chemical Formula
Subscript
Ionic Bond
Covalent Bond
Metallic
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COMPOUND
A substance made up of 2 or more different types
of atoms bonded together
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Chemical Formula
An expression that shows the number of and type
of atom in a compound For example C6H12O6 Types
of elements carbon, hydrogen and oxygen How
many (number) 6 Carbon, 12 Hydrogen, 6 Oxygen
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Subscript
A number written slightly below the and to the
right of a chemical symbol that shows how many
atoms of an element are in a compound.
C6H12O6
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Ionic bond

• The electric attraction between a negative and a
  positive ion.

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Covalent Bond
A pair of electrons shared by 2 atoms
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Metallic Bond
A certain type of bond in which nuclei float in a
sea of electrons
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Today's Topic

• How atoms are combined in a compound (bonded),
  determine the properties of the compounds

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CHEMICAL BOND The force holding 2 atoms together
in a compound.
3 Major Types of Bonds Metallic, Ionic, Covalent
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Metallic Bonds are caused by mobile (moving
electrons), this gives metal atoms the freedom to
move around, therefore metal bend
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Ionic Bonds are caused by the formation of ions,
this bond allows salt to dissolve in water. When
an ionic compound dissolves it separates into
ions which conduct electricity. Whereas
covalent bonds do not!
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Covalent bonds the atoms share electrons,
sometimes one atom pulls to hard on the electrons
giving the atom 2 oppositely charged ends.
What do you know about opposites THEY
__________________
ATTRACT
Therefore these molecules will stick to each
other...this is called COHESION
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COHESION The attraction between 2 like
Molecules!!!!
Example H2O
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SURFACE TENSION ON A PENNY!
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The water forms a bubble on the penny! This is
due to surface tension caused by the attraction
of the water molecules to each other. Instead of
falling off the penny the water molecules hold
each other in place creating a dome on the penny.

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Capillary Action Take a look at your celery,
write down what you notice on the back of your
lab.
Capillary Action - the tendency of water to
travel up a small narrow tube. This is also
caused by the polar covalent bonds in the water
molecule
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• COHESION water to water, molecules of the same
  substance attract.
• ADHESION water to tube (xylem), molecules of
  different substances attract.
• Water flow up the xylem of plant due to the uneq

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Cohesion (attraction) between the water
molecules, and the Adhesion between the xylem and
the water cause the water to move up the small
tubes called xylem in the celery
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Warm up Define the following terms on the front
of your compounds packet
Molecule
Polar Covalent Bond
NonPolar Covalent Bond
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MOLECULE

• A group of atoms that are held together by
  covalent bonds so that they move as a unit.

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Polar Covalent Bond

• The unequal sharing of electrons between 2 atoms
  that gives rise to negative and positive regions
  of electric charge.

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Non-Polar Covalent Bond

• The unequal sharing of electrons between 2 atoms

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COMPOUND
A substance made up of 2 or more different types
of atoms bonded together
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CHEMICAL BOND The force holding 2 atoms together
in a compound.
3 Major Types of Bonds Metallic, Ionic, Covalent
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• Compounds are 2 or more elements held together
  with a CHEMICAL BOND.
• Properties of compounds depend on the elements
  that make them up and how those element are
  BONDED to each other. These properties are
  usually very DIFFERENT from the individual
  elements that make them up.

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• The same elements can form different different
  compounds with different properties
• Example
• H2O water - safe to drink, does not kill
  bacteria
• H2O2 hydrogen peroxide, makes you
• vomit, used to kill bacteria

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• Bonding Occurs due to the fact that every atom
  wants to acquire
• 8 VALENCE ELECTRONS
• - VALENCE ELECTRONS are the electrons in the
  outermost energy level of an atom (farthest away
  from the nucleus)
• - A Full valence shell requires 8 valence
  electrons. With the exception of Helium because
  helium 1st energy level is filled with only 2.

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Draw a Bohr model diagram of helium-4 and label
the valence electrons 4 P M E N valence
e- Questions does helium-4 have a full valence
shell ____________
He
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Draw a Bohr model diagram of carbon-14 and label
the valence electrons 14 P M E N
valence e- Questions does carbon-14 have a full
valence shell ____________
C
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Draw a Bohr model diagram of Neon-20 and label
the valence electrons 20 P M E N
valence e- Questions does Neon-20 have a full
valence shell ____________
Ne
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3 Main Types of Bond

• Metallic Bonds
• Covalent Bonds
• Ionic Bonds

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• METALLIC BOND Bond between 2 METALS.
• Considered to be a "sea of electrons" with
  positive and "islands" (nuclei)

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• Black electrons, VValence electrons,
• Blue proton, Red neutrons

V
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• 2. COVALENT BOND electrons are SHARED.
• A bond between 2 NON-METALS

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• 2 Types of Covalent Bond
• POLAR and NON-POLAR
• NON-POLAR BONDS an equal sharing of electrons,
  between atoms. Occurs between 2 atoms of the
  same element.

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v
v
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• 2. Polar Bonds an UNEQUAL sharing of electrons
  between atoms. Occurs between 2 atoms from
  different elements.
• Bond between two different elements of atoms
  (element)
• - Creating a slight negatively charges side and a
  slight positively charged side.

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• The polarity causes CAPILLARY ACTION, ADHESION,
  COHESION, SURFACE TENSION, and allows plants move
  water up their stems for photosynthesis

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Cohesion

• Attraction between 2 LIKE molecules
• (2 of the same types of molecules sticking
  together)

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Adhesion

• Attraction between 2 UNLIKE molecules
• (2 different type molecules sticking together)

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Surface Tension

• Cohesive forces in water that cause it to bead
  and form a thin elastic film layer

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• Capillary Action - the tendency of water to move
  up a narrow tube. (Caused by the adhesion
  (attraction) of the water molecule to the side of
  the tube, and cohesion (attraction) between the
  water molecules. The water sticks together and
  pulls a trail of water up the tube (attraction)).

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Use your notes to define the following terms on
the vocab list on the front of your
packet Cohesion Adhesion Surface
Tension Capillary Action
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• Warm up
• What is an ion?
• Positive charge ________ electrons
• Negative charge ________electrons
• How is Mg2 different from neutral magnesium Mg

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• 3. IONIC BOND Bond between 2 oppositely charged
  IONS.
• A bond between a NON-METAL and a METAL

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• An electron is TRANSFERRED from the metal,
  creating a positive charged ion called the
  CATION. This transfer created a negatively
  charged non-metal referred to as an ANION.

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• The POSITIVE ion is attracted to the NEGATIVE
  ion, holding the two atoms together.

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• The positively charged ion can also be attracted
  to a positively charged particle referred to as a
  POLYATOMIC ion. Which is basically a compound
  (molecule) with a positive or negative charge.

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EXAMPLE NaCl Table Salt Metal (cation)
__________, gives up an electron
creating a ______________
ion. Nonmetal (anion) _________,
accepts the electron creating a
_____________ ion Positive and negative
charges _____________ each other, creating a bond
holding the compound together.