Do Now. On the piece of paper, indicate whether the following characteristics are associated with ionic or covalent compounds

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2 Do Now On the piece of paper, indicate whether the following characteristics are associated with ionic or covalent compounds 1. Electrical conductivity in aqueous solution 2. Relatively low melting point 3. High solubility in water 4. Electrical conductivity as a solid

3 Electrical conductivity in aqueous state Aqueous state simply means dissolved in water Ionic-will conduct electricity in aqueous state Covalent-will not conduct in aqueous state

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5 Melting Point The temperature at which a substance changes from solid to liquid The substance itself isn t changed (ex. When ice melts and becomes water it is still H 2 O) Melting point is related to intermolecular forces

6 Intermolecular Forces The attraction between molecules A substance that melts at a higher temperature than another substance will have stronger intermolecular forces because it takes more energy to break the substance apart

7 Solubility in H 2 O Ability to be dissolved in water Ionic compounds will easily dissolve in water Covalent compounds generally don t dissolve or have lower solubilities than ionic compounds

8 Electrical conductivity as a solid Neither type of compound will be able to conduct electricity as a solid so it is not a trait that can be used to identify the type of substance

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10 Do Now 1. Name the following and indicate if ionic or covalent a. FeS b. N 2 O 3 2. Write the formula and indicate which is ionic/covalent a. Barium Hydroxide b. Nickel (II) Nitride

11 Bell Ringer On your desk is an index card with any missing work you owe. It also has your current grade on it as well as the grade you d get if you turned in none of that work. If you re missing work, figure out if you have it or need a new one. If you need a new one, see me at the end of class Any last minute questions before the quiz?

12 Steps to go from formula to name-ionic 1. Identify metal. Check periodic table to see if it has multiple oxidation states. If yes, indicate with roman numerals. If no, roman numerals are not necessary 2. Identify nonmetal. If a single element, drop ending and add -ide (ex. Chlorine becomes chloride, oxygen-->oxide). If polyatomic (multiple elements) ion, check Table E for name. Don t change ending for polyatomics

13 Steps to go from name to formula-ionic 1. Identify the cation (positive metal) and anion (negative nonmetal) and write symbols with charges 2. Criss-cross method to bring charge down to opposite element. Only bring down number, not positive or negative sign. 3. If polyatomic ion is present, place entire ion into parentheses 4. Remove charges from formula and reduce numbers for atoms

14 Steps to go from formula to name-covalent 1. Identify the two nonmetals. Keep the first one the same and change the ending of the second one to -ide 2. Use prefixes to indicate how many of each element are present (mono, di, tri, tetra, penta, hexa, hepta ) *The only time a prefix isn t need is if there is only one atom of the first element *If the prefix ends with an O or A and the element starts with a vowel, drop the O/A Ex. CO 2 is carbon monoxide rather than monocarbon mono-oxide

15 Steps to go from name to formula-covalent 1. Determine the symbols for the elements present 2. Then indicate how many atoms of each element are present based on the prefixes given ***Don t reduce formula numbers like with ionic compounds. N 2 O 4 stays as N 2 O 4, not NO 2 ***

16 Reminders The tiny numbers up top next to an element are the charges When writing the formulas for neutral compounds, we should have no charges written in the formula The tiny numbers at the bottom indicate how many atoms of each element are present (don t need to write if there is just 1) The 1st letter of a symbol is always capitalized, the 2nd is always lower case

17 Covalent Bonds Bonds formed by the sharing of electrons between atoms If the atoms bonded together are the same element, it is considered a diatomic molecule ex.) O 2 and H 2

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19 Covalent bonds can also be between different elements This can lead to two types of covalent bonds Nonpolar covalent bonds-equal sharing of electrons. An electronegativity difference of Polar covalent bonds- an unequal sharing of electrons. An electronegativity difference of

20 Electronegativities Carbon=2.6 Fluorine=4.0

21 Dipole moment A measure of the electrical polarity of a system of charges, or a measure of the separation of positive and negative electrical charges within a system Indicated with an arrow going from the more positive to the more negative atom

22 Electronegativities Hydrogen=2.2 Fluorine=4.0

23 What type of covalent bond would form? Sulfur and Chlorine Nitrogen and Oxygen Carbon and Oxygen

24 What type of covalent bond would form? Sulfur and Chlorine POLAR Nitrogen and Oxygen Carbon and Oxygen

25 What type of covalent bond would form? Sulfur and Chlorine POLAR Nitrogen and Oxygen NONPOLAR Carbon and Oxygen

26 What type of covalent bond would form? Sulfur and Chlorine POLAR Nitrogen and Oxygen NONPOLAR Carbon and Oxygen POLAR

27 Molecular Polarity More complex than bond polarity Need to take into consideration electronegativity differences as well as symmetry

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36 Drawing Molecules Sometimes you won t have the structure given to you. When this happens draw out structure according to the steps on the note sheet given you

37 H 2 O Use steps to draw the structure for water

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39 Memorize the shape of water It is called a bent molecule

40 CO 2 Again use the steps to draw this molecule.

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