Step 1: Solute particles must separate from each other. Since energy must be absorbed to overcome the forces of attraction between solute particles,

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2 Step 1: Solute particles must separate from each other. Since energy must be absorbed to overcome the forces of attraction between solute particles, this process is endothermic.

3 Step 2: Solvent particles must separate from each other. Since energy must also be absorbed to overcome the forces of attraction between solvent particles, this is endothermic.

4 Step 3: Solvent particles surround and attach themselves to solute particles. These attractions release energy just like when ionic or covalent bonds are formed, but not as much energy. This is exothermic.

5 Resulting solutions can be either exothermic or endothermic When more energy is required for the solution to form the solution overall will be endothermic When more energy is released when the solution forms the solution overall will be exothermic

6 Solvation is when no particular solvent is mentioned, the solute particles are said to be solvated. Hydration is when water is the solvent, and the solute particles are said to be hydrated.

7 The reason why a solute may or may not dissolve in a solvent is related to the forces of attraction between the solute and solvent particles From this, there are two ways to form a solution...

8 One: There are strong forces of attraction between solute and solvent particles How The particles of solute will separate from each other The particles of solvent will separate from each other This is due to the strong attraction between solute and solvent

9 Two: If there are very weak forces of attraction holding solute particles together and holding solvent particles together How The particles of solute will separate from each other The particles of solvent will separate from each other This is due to weak attraction within solute and within solvent

10 This applies to molecules two or more non-metals covalently bonded together Although they are sharing electrons, one atom will attract the electrons shared more closely, making it slightly more negative, and the other atom slightly more positive.

11 Atom is more electronegative, it is pulling electrons closer to itself. Atom is more electropositive, its electrons Atom is more electropositive, its electrons have been pulled farther away.

12 A non-polar molecule is one that the electrons are distributed more symmetrically and thus does not have an abundance of charges at the opposite sides. The charges all cancel out each other.

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14 In order to understand polarity you must recall your VSEPR theory knowledge Review pages in your textbook Do the following questions for practice: Page 193 # s 6 (a, e, f, g) 7 (a, b, c) Page 196 # s 8, 9, 10 Page 201 # s 1 & 3

15 Forces binding atoms in a molecule are due to chemical bonding Intramolecular forces: forces that bond the atoms to each other within the molecule.

16 Dipole = polar molecule Dipoles will change their direction so that their oppositely charged ends are near to one another. The electrostatic attraction between the ends is dipole-dipole force

17 The force of attraction between an ion and a polar molecule. NaCl breaks up because the ion dipole with water is stronger than the attraction of Na + to Cl -

18 weakest intermolecular force between non polar molecules It is a temporary It is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles

19 It is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. The molecule involved with hydrogen bonding should have at least one lone pair. More lone pairs = stronger hydrogen bonds.

20 Ionic solutes dissolve in polar solvents (ex: NaCl and H 2 O) Non polar solutes dissolve in non polar Non polar solutes dissolve in non polar solvents (ex: solid I 2 and liquid Br 2 )

21 Ionic solutes WILL NOT dissolve in non polar solvents Non polar solvent cannot attract the particles of the ionic compounds strongly enough to separate them Non polar solutes WILL NOT dissolve in polar solvents

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