1. Periodic Trends

2. Atomic Size Every atom has a nucleus and electrons zooming around it How far the outermost electron is from the nucleus determines the size of the atom

3. Atomic Size Trend GENERALLY As you move down a family atomic size increases As you move across a period atomic size decreases

4. Explaining the trend As the # of protons increases, there is a greater attraction between them and the electrons  makes the atom’s smaller BUT each additional energy level means electrons are farther away from the nucleus  makes the atom bigger

5. More explanation Because extra orbitals is a stronger force than the attraction between protons and electrons, atomic size increases down a group, but decreases across a period.

6. I still don’t get it!!!! As you go down the table the size increases, but decreases left to right B/C you get extra protons as you move across Alkali metals are always the largest in their period, while noble gases are always the smallest

7. Practice using the trend put them in descending order A. Li, C, F B. Li, Na, K C. Ge, P, O D. C, N, Si E. Al, Cl, Br

8. answers Li, C, F K, Na, Li Ge, P, O Si, C, N Al, Br, Cl

9. Ionization Energy the energy required to remove the outermost electron from an atom.

10. Ionization energy cont… When enough energy is added to an atom the outermost electron can use that energy to pull away from the nucleus completely leaving behind a positively charged ion.

11. What if? If the ionization energy is high, that means it takes a lot of energy to remove the outermost electron. If the ionization energy is low, that means it takes only a small amount of energy to remove the outermost electron.

12. Ionization Trend the ionization energy of the elements decreases as you go down the periodic table because it is easier to remove the electrons as a general trend, from left to right across the periodic table, ionization energy does increase

13. Answer these as a class Why does ionization increase from left to right? Why does ionization energy decrease down a group? Why isn’t there a second ionization energy for Hydrogen? Why is the ionization energy for a noble gas so high?

14. One more thing about I.E. As the size of the atom increases, nuclear charge has a smaller effect on the electrons in the highest energy level  Less energy is required to remove the first valence electron

15. Electronegativity/ Electron Affinity Ability of an atom to attract or gain electrons, respectively

16. Electron affinity Trend Same as ionization energy and electronegativity Why are these three trends the same???

17. Reactivity A highly reactive element reacts very easily, maybe even violently, with lots of other elements or compounds. What are the most reactive elements? Least reactive?

18. Ionic Size Cations are always smaller than the metal atoms they used to be Anions are always bigger than the non-metal atoms they use to be

19. * Things to recall from ICP An ion is a charge atom or group of atoms a Cation is a positive ion an Anion is a negative ion

20. Explaining the trend When an atom loses an electron the attraction between the remaining electrons and protons is greater so the ion is smaller Because anions gain electrons the attraction between any one electron and the nucleus is less making the ion bigger

21. Ionic Size Ionic size increases from top to bottom From left to right cations and anions decrease in size. WHY????