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Ions and Ionic Compounds (Review). If the fish in your fish tank are ill or dying, why?! What can you test for in the water?What type of calculations can you use to determine this?Remember that when ionic compounds dissolve in water
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1. Inappropriate Molecular Substance Concentrations? 1C.10 Molecular Substances, Polarity, and Electronegativity
2. Ions and Ionic Compounds (Review) If the fish in your fish tank are ill or dying, why?!
What can you test for in the water?
What type of calculations can you use to determine this?
Remember that when ionic compounds dissolve in water
they break into their ions
3. Molecular Substances Molecular compounds are 2 nonmetals
Is it possible that the cause of my fish dying could be a dissolved molecular substance?
When molecular substances dissolve in water they do not form ions in solution. The molecules stay intact.
Examples: Sugar, Ethanol
4. Molecular Attraction Ionic Compounds
Crystalline solids at room temp.
Due to the very strong attraction between +/- ions
Very polar compounds (distinct areas of + and charge)
Molecular Compounds
Solids, liquids, or gases at room temp.
Depends on the attractions between molecules (strong = solid, moderate = liquid, weak = gases)
Can be polar or nonpolar
5. What determines the solubility of a molecular substance in water? Attraction of a substances molecules for each other compared to their attraction for the solvent molecules.
Amount of attraction depends on the distribution of electrons within the molecules = the polarity
Like dissolves like!
Student Web>Unit 1>Section C> Solubility of Molecular Substances
7. What Affects Polarity? Atoms are bonded together by the attraction of one atoms (+) charged nucleus and anothers (-) charged e-.
Not all atoms have the same level of attraction to other atoms (-) charged e-
Ionic Compounds: the difference in this e- attraction between atoms is very large
the e- are transferred from one atom to the other = IONS!!
Ionic compounds = metal + nonmetal
8. What Affects Polarity? Molecular Compounds: two or more non-metals are joined together when the attraction between the (+) nucleus and the (-) e- is enough that the electrons are shared between atoms (not transferred).
Can be polar or nonpolar: electrons are not always shared equally
not all atoms have the same level of attraction to other atoms (-) charged e-
9. Electronegativity: Ability of an elements atoms to attract shared e- when bonding within a compound
The difference in electronegativity between the bonding atoms determines the polarity and thus strength of the bond.
The greater the difference the more polar the bond.
Example: Water, O is more electronegative than H so H2O is a polar molecule with the concentration of negative charge over the O
10. Ionic vs. Molecular Substances