List how many protons, neutrons, and electrons in the following isotopes Silver 109 47 p + and e ; 62 n 0 Molybdenum 96 42 p + and e ; 54 n 0 Scandium 45 21 p + and e ; 24 n 0 1of 26
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Review: Which element has the greater first ionization energy? A. Li B. B (It takes more energy to remove an electron if it has a greater ionization energy.) 3of 26
Review Which element has the larger atomic size? A. Li B. Rb 4of 26
Review: Which element has the greater first ionization energy? A. F B. Li 5of 26
Review: Which element has the greater second ionization energy? A. K B. Ca 6of 26
Periodic Trends 1. Atomic Size 2. Ionization Energy 3. Ionic Size 4. Electronegativity 7of 26
Metallic elements have low ionization energies They form positive ions easily 8of 26
3. Ionic radii Positive ions/cations are always smaller than the atoms from which they formed They lose e Protons in nucleus pull remaining e closer 9of 26
Negative ions/anions Always LARGER than the atoms from which they are formed More electrons but same number of protons = less effective attraction from the nucleus. E s spread out more, making ion larger. 10 of 26
6.3 Periodic Trends > Trends in Ionic Size Relative Sizes of Some Atoms and Ions 11 of 26
Periodic trend for ionic size Ionic size generally increases from top to bottom of table within a group. Explanation: greater # of energy levels and the shielding effect. 12 of 26
Within a period: two trends 1. Cations Size of small cations decreases across a period 2. Anions When anions are reached in a period, size of ions becomes large, then decrease from left to right across a period 13 of 26
6.3 Periodic Trends > Trends in Ionic Size Trends in Ionic Size Size generally increases 14 of 26
4. Electronegativity The tendency of an element to attract e in compounds. The more electronegative the element, the more it is an electron hog. Doesn t have a unit: Linus Pauling made the scale in arbitrary units Noble gases are not on the scale because they do not form compounds The scale ignores transition metals 15 of 26
Periodic Trend: Electronegativity As you go across a period from left to right electronegativities INCREASE As you go down the periodic table electronegativity DECREASES (same trend as ionization energy) Explanation: Octet rule, and shielding effect. 16 of 26
Range of electronegativity scale: Cs = 0.7 (lowest) F = 4.0 (highest) 17 of 26
6.3 Periodic Trends > Trends in Electronegativity Representative Elements in Groups 1A through 7A 18 of 26
6.3 Periodic Trends > Summary of Trends Electronegativity Ionic Shielding Nuclear Ionization Atomic Size of size cations anions Size Charge energy Decreases Constant Increases Increases Decreases 19 of 26
Review: Which element has the greater electronegativity? A. Li B. F 20 of 26
6.3 Section Quiz Which of the following sequences is correct for atomic size? A. Mg > Al > S B. Li > Na > K C. F > N > B D. F > Cl > Br 21 of 26
6.3 Section Quiz Metals tend to A. gain electrons to form cations. B. gain electrons to form anions. C. lose electrons to form anions. D. lose electrons to form cations. 22 of 26
6.3 Section Quiz Which of the following is the most electronegative? A. Cl B. Se C. Na D. I 23 of 26
Review: Which element has the greater electronegativity? A. Li B. Cs 24 of 26
Review: Which element has the greater electronegativity? A. O B. S 25 of 26
Read/Study pg. 178 WS 6.3 26 of 26