Transcript PowerPoint Version

http://www.bing.com/images/search?q=keep+calm+what+do+you+mean+it%27s+only+tuesday+picture&FORM=HDRSC2&adlt=strict#view=detail&id=1991D8431243284FA0C4BCA87C1D189D0E4F0930&selectedIndex=0
Please turn in:
 Self-Reflection #7
 Lab Rubrics for Solution to Solutions
Ionization versus Dissociation
 Energy is required to remove a negative charge
from a positive charge. (because you need energy
to overcome the force of attraction, opposites
attract).
 Ionization: the process of removing an
electron from an atom (i.e., separating positive
and negative charges)
 Na 0 + IE
11e11p+
+ IE
Na1+ + e10e11p+
+ e-
Forming a sodium ion from a
neutral Na atom requires energy.
The electron on the right can
transfer to another particle
Ionization versus Dissociation
 Dissociation: the process of separating positive
and negative ions from a crystal lattice. (i.e.,
separating positive and negative charges)
NaCl(s)
Na 1+(aq) + Cl- (aq)
Symbol representation of dissociation. Sodium chloride (solid
NaCl) dissociates in water to form sodium ions (Na+) and
Chloride (Cl-) in an aqueous solution.
Ionization versus Dissociation
 Ionization and Dissociation are both
processes where positive and negative charges are
being separated.
 What’s the difference???
 Ionization: forces WITHIN the particle
 Separation of protons and electrons
 Dissociation: forces BETWEEN particles
 When the ions are separated in the crystal lattice
 What’s the crystal lattice?
Ionization versus Dissociation
 Ionization
Dissociation
-
++++
++
-
-
• Depends on forces inside an
atom (between electrons and
protons)
• Ionization energy is the
energy required to remove an
electron from a neutral atom
• Depends on forces between
atoms (between positive and
negative ions)
• Occurs because of solvation.
• Ions separate in solution
Trends in Ionization Energy
Ionization Energy Decreases
Ionization Energy Increases
Ionization versus Dissociation
 Ionization energy is like “electron greed”.
 How badly does the atom what to hold on to its
electron?
 Lower I.E. means it is easier (takes less energy) to
remove an electron from the atom and create
an ion.
 Higher I.E. means it is more difficult (takes more
energy) to remove and electron from the
atom and create an ion.
Ionization versus Dissociation
 P&P #4: Make a Venn diagram to illustrate the
similarities and differences between ionization
and dissociation.
P&P #4 p. 130
Ionization versus Dissociation
 Ionization energy can help us to predict the
type of bond that will form between two atoms.
 HOW???
 Bond type depends on differences in electrical
properties. Let’s try to find a trend…
Ionization versus Dissociation
 P&P #5a: Predict the relative ionization energies
associated with ionic, covalent, and polar bonds.
 Ionic bonds form when particles have opposite
net charges (IE energy is High)
 Example: Na + + Cl –
 One particle loses an electron
 Which one?
 The ionization energies of 2 atoms in an Ionic solid are
very far apart (just like their location on the Periodic
Table)
Ionization versus Dissociation
 P&P #5a: Predict the relative ionization energies
associated with ionic, covalent, and polar bonds.
 Covalent bonds have the same tendency to attract
electrons so they act more neutral (IE energy is low)
 Example: CO2
 Why?


The atoms involved in bond have the same tendency to
attract electrons
Look at the locations of Carbon and Oxygen
 Polar bonds are between ionic and covalent
 H20
Ionization versus Dissociation
 P&P #5b: Predict what type of bonding
(Covalent, ionic, or polar) occurs between
hydrogen atoms in the elemental compound H2
 Hydrogen gas has two atoms that are the same.
 Ionization energies are equal
 If the energy is equal, than any electrons involved
in bonding will be shared equally= COVEALNET
Ionization versus Dissociation
 P&P #5c: Draw a series of molecular level
sketches to show whether hydrogen gas H2 is
highly soluble in water.
H
H
O
H
No dipole
No interaction
H
Hydrogen gas (H2) molecule interacting with water.
Hydrogen’s low solubility in water is due to hydrogen
being non-polar and water being polar
Charge Those Particles –
Day 3 Sharing Electrons
p. 125
Part III: Sharing Electrons
 Read Intro p. 131
 Read “Electronegativity” p. 132
 Take notes!
 Make a Venn Diagram to compare and contrast
electronegativity and ionization.
Entry Task
 Represent the Ionization of Potassium (K):
 Represent the Dissociation of Magnesium
Chloride (MgCl2)
Entry Task
 Would you expect the Ionization Energy of
Chlorine (Cl) to be higher or lower than the
Ionization Energy of Radium (Ra). Explain.
Charge those Particles – Day 3
 Learning Target:
 I can describe chemical bonding between
atoms.
Electronegativity
 Covalent bonds form when atoms have similar
electrical properties.
 Ionization energy is one way to quantify those
electrical properties
 Electronegativity is another way to quantify
electrical properties.
Electronegativity
 Electronegativity is the ability of an atom to
attract electrons.
 The higher the electronegativity, the more
strength the atom has to pull electrons toward
itself.
Electronegativity
 Electronegativity is the ability of an atom to
attract electrons.
 The electronegativity scale was devised by Linus
Pauling.
 It is an arbitrary scale with Fluorine (the most
electronegative element) having a value of 4.
 All other electronegativities are assigned relative to
Fluorine.
 Why Fluorine??
Electronegativity
 Differences in electronegativity between two
atoms can tell you what type of bond will form
between those atoms.
 If two atoms have similar electronegativities,
neither is stronger than the other. They will
share electrons equally… this is a covalent
bond.
Electronegativity
 If two atoms have somewhat different
electronegativities, one atom is slightly stronger
than the other. They will share electrons
UNequally… this is a polar covalent bond.
 They are still sharing electrons, but the electrons
spend more time around the more electronegative
atom (giving it a slight negative charge), and less time
around the less electronegative atom (giving it a slight
positive charge) creating a dipole.
Electronegativity
 If two atoms have very different electronegativities,
one atom is much stronger than the other. The
stronger atom will take the electron(s) from the
other atom. This is an ionic bond.
 The atom that takes the electron(s) becomes a negative
ion.
 The atom that gives up the electron(s) becomes a positive
ion.
 The ions are attracted to each other and form a crystal
lattice.
Predicting types of bonds…
Type of bond
Non-polar
covalent
Polar covalent
ionic
Electronegativity
difference
< 0.4
0.4 – 2.1
> 2.1
Electrons
Shared Equally
Shared Unequally
Transferred (not
shared)
Example
O2 or H2 or CO2
H2O
NaCl
Terms
Covalent molecule
Polar molecule
(with a dipole)
Ionic compound
(i.e., salts)
Electronegativity
 What trends do you see in
electronegativity?
 What type of bonds form when atoms from
opposite sides of the periodic table for a
compound?
Trends in Electronegativity
Electronegativity Increases
Electronegativity Increases
Questions
 P&P #1 p. 131: Make a Venn diagram to compare and
contrast Ionization and Electronegativity
 P&P #3a p. 134: Make a diagram to show how each
pair of atoms listed below shares or transfers electrons
and determine the type of bond:
 Hydrogen – Oxygen in water
 Carbon – Oxygen in CO2
 Potassium – fluorine in KF
 Carbon – Hydrogen in CH4
 Bromine – Bromine in Br2
Reflect & Connect
 Complete R&C #1-3 p. 135 & 139
 Read “Water works” p. 136 & take notes
 Read “Mysterious Metals” p. 138 & take
notes
Discuss R&C
Water Works
Mysterious Metals
Reflect and Connect
MINI-LAB
For this activity you will need:
 1 worksheet packet for each student
 1 atom skeleton for each student
 1 valence skeleton page per student (they will need to cut
these out and work in pairs to show bonding)
 20 skittles per student (all same color) (partners should have
different colors to help show electron sharing/transfer)
Balance Chemical Equations
 http://www.youtube.com/watch?v=HB6cG7bQew0&featu
re=youtu.be
 WKST # 1
 WKST #2
Review Videos
 Bohr:





http://www.youtube.com/watch?v=ImhcblZaydo&feature=youtu.be
Ionization:
http://www.youtube.com/watch?v=p4KQ3PoJeGg&feature=youtu.be
Electronegativity:
http://www.youtube.com/watch?v=kzeRs5fQBp4&feature=youtu.be
Covalent Bonding:
http://www.youtube.com/watch?v=rBxhfR8Ds8c&feature=youtu.be
Polar:
http://www.youtube.com/watch?v=ZpGzapEyyoY&feature=youtu.be
Ionic: http://www.youtube.com/watch?v=jdJmEOy2mw&feature=youtu.be