Chemical Bonding `

The Nature of Chemical Bonding A ______________ results from the simultaneous attraction of _________ to two ____________. _________ energy is _________ in the chemical bond . This energy is equivalent to ___________ due to position or condition of the bond. When a chemical bond is formed in a reaction, energy is _________. They are in a _________ energy position then when they are separated. When a chemical bond is broken energy is __________. The atoms separated have _______ energy.

Bonding and Stability A compound represents a __________ energy condition than its individual atoms and is generally considered __________ stable. In general chemical changes will occur among atoms if the changes lead to a ________ energy condition and hence a ________ stable structure. Bond _________ is favored. In general ________ reactions in nature are favorable.

Bonds Between atoms Goal: ____________ measures the tendency of the atom to attract a shared pair of electrons.

Electronegativity difference and Bond type Ionic Bond Covalent Bond Transfer of electrons Metal and nonmetal E.N difference≥1.7 Greater the E.N. difference the greater the ionic character Sharing of electrons Nonmetals E.N. difference between 0 and 1.7 E.N. difference=0 is a nonpolar bond (equal share. (<.3) E.N difference between .3 and 1.7 polar bond (unequal share)

Metallic Bond Positive ion immersed in a sea of mobile electrons Metals only Few valence electrons Low ionization energy

Determine the electronegativity difference for each compound and determine the bond type NaCl CaBr2 BaO HCl H2O Cl2

Try these too!! NaH CaH2 Cu Mg

Without figuring out the electronegativity difference what bond type do these compounds have? CuSO4 NaNO3 NH4Cl Why?

Part 2: Bond Types

Ionic Bonding (Electrovalent) _____________of ______________ Between a ___________ and a ___________. A __________ loses an electron to form a _______ ion called a __________. A ___________ gains an electron to form a ______ ion called an _______. The ions are drawn together by electrostatic forces and form an ionic compound known as a ________. The greater the elctronegativity difference the greater the ionic character and the stronger the attractive forces. (electronegativity difference≥1.7)

Show the bond between sodium and chlorine.

Show the bond between calcium and fluorine.

Covalent bonding ____________ of ____________ Between ______________. If the electrons are shared equally they form a _______ _________ _________. Electronegativity difference =0 or <.3. For example: _____________ If the electrons are shared unequally they form a ________ ________ _______. Electronegativity difference between .3 and 1.7. Two _________nonmetals. The greater the electronegativity difference the greater the polarity or ionic character. Covalent compounds form _____________. Molecules may be ____________ or ___________ Or they can be _____________ or _____________. The bond type and molecule type may be different.

Nonpolar bond: (equal sharing) F2 Note: A _______ bond represents ______pair of electrons or _____electrons

O2 Note: A _________ bond stands for _____pairs of electrons or __________ electrons. N2 Note: A ________bond stands for ______pairs of electrons or ________electrons.

Polar Covalent Bond: (unequal share) HCl BrCl

Diatomic molecules (2 atoms) If the atoms are the same the bond is ________(equal share) and the molecule is _________(symmetric) If the atoms are different the bond is ________(unequal share) and the molecule is _______ (asymmetric) A polar molecule is also called a __________ because it has______________.

More than two atoms If a molecule is made up of more than two atoms the bond may be __________ (unequal share) but the molecule may be ___________(symmetric) or ____________(asymmetric) Molecules are a SNAP S(symmetric)N(nonpolar)A(asymmetric)P(polar)

Try these!!!! CH4 CO2

And These!!!! H2O NH3

Coordinate Covalent Bond Water and ammonia both have________________. They can form a coordinate covalent bond. A coordinate covalent bond is one formed when two shared electrons forming a covalent bond are both donated by one of the atoms and the other atoms donates none. Once the coordinate covalent bond is formed it behaves as an ordinary covalent bond. The difference _______________________________. The __________ ion can attach to the water and ammonia molecule forming the ____________ ions called ___________ and ______________. (table __)

Try these!!!! H3O+ NH4+

Let’s Mix it up!!!!! What kind of bond are these? Practice time!!!!!

Part 3: Shapes and Polarity of molecules See sheet on shapes and polarity

Part 4: Forces that hold compounds together

Ionic compounds: Bond is ionic between a _______ and a _________. Form ionic compounds called_________. Each compound is attracted to another compound by an ________________ ____________ between the + ion in one compound and the – ion in an adjacent compound. Very strong force making them solids at room temperature. Stronger the force of attraction the ________the boiling point.

Intermolecular Forces of Attraction: Forces of attraction between molecules: _________bonded substances. Note: intramolecular forces are within a molecule between the atoms. (polar and nonpolar bonds) Depends if a molecule is a nonpolar molecule (symmetric) or a polar molecules (asymmetric) Three types Dipole-Dipole Hydrogen bonding Van Der Waals forces

Dipole-Dipole Attraction: Force of attraction that holds ______ molecules together. Not as strong as the electrostatic attraction between ionic compounds. Most polar molecules are _________ at room temperature.

Hydrogen Bonding: Special type of dipole-dipole aat attraction. Occurs when hydrogen from one One molecule is attracted to an atom of _________ atomic radius and ________ electronegativity in an adjacent molecule. Three elements that undergo hydrogen bonding are:_______, _________, and _______. Examples of molecules with hydrogen bonding are:_______, ________, and________.

Special characteristics of hydrogen bonding The covalent bond between the atoms is stronger than the hydrogen bond between the molecules. Stronger than a regular dipole-dipole. Accounts for an abnormally high boiling point and freezing point of a similar compound. For example: Which has the highest boiling point? HCl HF HBr HI The _________ the intermolecular force of attraction the ________ the boiling point.

Van-Der Waals Forces (london dispersion forces): Only force of attraction in _________ molecules. Very ______ forces of attraction present in all matter. Are due to the motion of electrons in atoms or molecules resulting in __________ (___________) dipole-dipole attraction.

Special characteristics of Van-der waals forces Nonpolar molecules are usually ________ at room temperature. Allows small nonpolar molecules (ex: Hydrogen, helium ,carbon dioxide, etc.) to exist in the liquid and solid phase under conditions of _______ temperature and _________ pressure. Why? The molecules become _________ together _____ the strength of the van der waals forces. An increase in molecular mass will ________ the van der waals forces.

For thought: Explain the phases of the halogens in terms of van der waals forces? Which has the highest boiling point? CH4 C2H6 C3 H8 C4 H10

Comparison of the forces holding compounds/molecules together Strongest: ___________________ ______________________________ Weakest: ______________________________ Which has the highest boiling point? Carbon dioxide Ammonia Hydrochloric acid Sodium chloride

Molecule-Ion Attraction:

Rules of solubility Ionic and polar covalent solutes ex:_______ and _________ are generally soluble in polar solvents ex: _______ and are relatively insoluble in nonpolar liquids. Nonpolar solutes such as CCl4 are soluble in nonpolar solvents such as C6 H6 and are relatively insoluble in polar solvents such as water. Key phrase: _____________________________

Summary:

Part 5: Types of Solids

Directions: In groups of four use your knowledge of chemistry along with websites to complete the table on Comparing types of Solids. Some key concepts to help you: The stronger the force of attraction holding the compound together the ______ boiling point. To conduct an electric current you need ________________ or in the case of a metallic bond _________________. Rule of solubility: Like dissolves like