4:17 to 4:19 1)Bondig occurs to increase stability  energy kinetic is released (exothermic)  this energy was stored (potential). answer is #1potential E 2) N(g) + N(g)  N 2 (g) + energy The two N atoms are joined with the nonpolar covalent Bond formed, and energy is a product and is released –exothermic ANS is #4 REVIEW FOR BONDING –STATES EXAM – FROM REVIEW BOOK CH 4 3) The attraction for electrons is electro negativity, the lowest is Na because: 1- it is towards the top-left of the table AND/OR table S assigns it the lowest electro negativity of all the choices. ANSWER is Na

4:17 # 4– To solve calculate the ionic character for each combination of elements. Aluminum has an electronegativity of 1.6 and gives the greatest ionic character with oxygen. And is Al. NOTE – this is a badly worded question – the least electronegative element element will allow O to share the most of its cloud, that is Al, the most electronegative element will have the greatest pull on the O electrons, that is S. #7 Ionic substances have ionic character of 1.7 or above. MgCl 2 is the answer ( ) = 1.9 ionic character. Also you have an active metal with a halogen. #9 All of them have H, therefore it is the other element that determines the ionic character. The greatest difference is with F (4.0 –2.1) = 1.9 ionic character.ANS is choice 2

#12 – Sr is in group two, therefore it will become a 2+ ion by losing 2 electrons, the ground state ATOM will have 2 more electrons than the ION. Choice 1 is ans. #13- They tell you that it conducts in the (l) and dissolved (aq) situations. This implies that it does not conduct in the solid state. They also mention crystalline solid. This is an ionic substance – choice 1 #14- NaCl(l) is ionic based on ionic character and it is a liquid,This is your answer as it will be conductive. NaCl(s) cannot conduct. C 6 H 12 O 6 is covalent and does not conduct.

#18 F 2 is nonpolar as the ionic character is 0, also two of the same atoms will share electrons equally. ANS is Covalent substances form molecules, no other type of substance does. Look for an ionic character of between 0 and 1.7 ans. is CO Soft and nonconductive indicates covalent compounds. The terms covalent and molecular are interchangeable in this context. AND is 1

29. The only solid conductors are metallic and graphite. Metals are known to conduct in all phases. AND is 1 #36 Al F F F  TRANSFER Al +3 + F [ [ - F [ [ - F [ [ - Al + 3 F  Al F -

38) a) Hard, high M.P and High B.P solid conductor is a metal. b) Hard, high M.P and High B.P liquid conductor is ionic c) Soft, low m.p. nonconductor is covalent (molecular). 4:27 # 1 H c H H H 1.The molecule is symmetrical and therefore cannot be polar. 2.The geometry is 4 bonds – tetrahedral –and symmetrical geometry. 3.Carbon is the most electronegative atom and is therefore the  -, and the H atoms are the = pole.

#3 Hydrogen bonds are strongest when polar charges are most concentrated (density) which means small radius and high electronegativity. Choice 3. #4 Hydrogen bonding is a type of dipole attraction between H and F, O or N. As a dipole attraction, the relative strength of attraction between different atoms increases with the relative ionic character between them. The ionic characters are: H 2 O ionic character is 1.4 very polar H 2 S ionic character is 0.5 weakly polar H 2 Se ionic character is 0.5 weakly polar H 2 Te ionic character is 0.0 totally nonpolar!

6-Dispersion forces (Van der Waals) increase in strength directly with molar mass (atomic mass for atoms). In this question He is the smallest ans. has the weakest forces. 14 – molecule-ion attractions are found when IONIC substances dissolve in water. In these choices the answer is KCl (aq). Hint look for the (aq) aqueous symbol. 8- In this question all of the atoms are noble gasses. The answer is 4 because they go from the largest (Xe) to the smallest choice (Ne). Dispersion forces become weaker with decreasing mass.

MOLECULE TO ION ATTRACTION ATTRACTION H OXYGEN H δ+δ+δ+δ+ δ-δ- H H δ+δ+δ+δ+ δ-δ- H H δ+δ+δ+δ+ δ-δ- H H δ+δ+δ+δ+ δ-δ- H H δ+δ+δ+δ+ δ-δ- H H δ+δ+δ+δ+ δ-δ- - ION + ION THE MOLLECULE TO ION ATTRACTION BETWEEN THE δ+ OF THE HYDROGEN POLE OF WATER AND THE – ION. THE MOLLECULE TO ION ATTRACTION BETWEEN THE δ- OF THE OXYGEN POLE OF WATER AND THE + ION. MOLLECULE ION ATTRACTION S ARE VERY STRONG AND HARD TO BREAK, MAKING THE SEPARATION OF WATER AND SALTS CONSUME LARGE AMMOUNTS OF ENERGY.

15- As in the diagram - the positive hydrogen pole of water faces a – ion, the negative oxygen pole attracts to the + ions. ANS is Calcium Phosphate is 18- The empirical formula is the one with the most reduced subscripts, Answer is K 2 O cause 2 and 1 cannot be reduced. Ca 2+ GROUP 2 IS 2+ PO 4 3- PHOSPHATE IS 3+,TABLE E Ca 3 (PO 4 ) 2