Does the image show ionic or covalent bonding? Support your answer. http://www.powayusd.com/pusdphs/webquests/chemwebquest/chemsite.htm

Objective Describe the difference between ionic bonds and covalent bonds.

Lab Pre-questions Lab setup When you finish your lab, clean up your station and return to your seat. Begin working on the post-lab questions.

Post-Lab Discussion Why is distilled water used for this lab instead of just tap water? (hint: think about what is in tap water) Tap water contains impurities (other substances besides hydrogen and oxygen). Many of these substances are ions, which will conduct electricity. Had we used tap water, our sugar solution could have conducted electricity – providing misleading results.

Post-Lab Discussion What properties in general do covalent-bonded substances have? Low melting/boiling points – evidenced by sugar melting in our flame test. Poor conductors of electricity – evidenced by lack of bubbles in battery test.

Post-Lab Discussion What properties in general do ionic-bonded substances have? High melting/boiling points – evidenced by lack of salt melting in our flame test. (salt has a melting point of 800oC!!) Good conductors of electricity – evidenced by production of bubbles in battery test. (bubbles are result of H2 gas production)

Post-Lab Discussion Which compound melted most easily? Is it ionic or covalent? Sugar – covalent

Post-Lab Discussion Using the periodic table explain how the position of the elements that make up sugar (C12H22O6) and Ethanol (C2H5OH) can be used to tell if the bonds are ionic or covalent. Located on right-hand side (except Hydrogen) Non-metals

Post-Lab Discussion Using the periodic table explain how the position of the elements that make up salts NaCl, CaCl2, KCl) can be used to tell if the bonds are ionic or covalent. Located on opposite sides of periodic table. Non-metal bonding with a metal.

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond2.html

Electronegativity Definition: Term: Characteristics: In my own words: Attraction an atom has for a shared pair of electrons in a chemical bond. Term: Electronegativity Characteristics: Fluorine is most electronegative element Increases diagonally to the right on periodic table As you move down a group, electronegativity decreases. Elements with the greatest difference in electronegativity form strongest ionic bonds. In my own words: Write the definition of electronegativity in your own words Mine: ability of an atom to attract an electron.

Image of Electronegativity

Properties of Ionic Bonds Electronegativity difference > 2. Typically a bond between metal and a nonmetal. Conduct Electricity. High melting/boiling points.

Properties of Covalent Bonds Electronegativity difference < 2. Typically a bond between 2 nonmetals. Do Not Conduct Electricity. Low melting/boiling points. Polar Covalent – unequal sharing of electrons. Covalent – equal sharing of electrons.

Oxidation Number Definition: indicates how many electrons are lost, gained, or shared when bonding occurs. Note: charge is written after the number Aligned with valence electrons Some atoms have more than one oxidation number

Chemical Formulas Tell us how many atoms are in each molecule Charge always equals 0 Criss-Cross method

Writing Formulas Positive ion always comes first, then your negative Na+ Cl- NaCl

Chemical Bonding Worksheet You will work with a partner to complete the worksheet. You will make a model of your atom using Fruity Pebbles as valence electrons. You MUST then draw your atom with its valence electrons and show which electrons are moving or being shared.