1. Periodic Trends

2. Chemical Periodicity Atoms participate in chemical reactions in order to fill their outermost s and p sublevels.

3. Some definitions… ionization energy – energy required to remove an electron from an atom electron affinity – energy required to add an electron to an atom electronegativity – tendency of atoms to attract e - when they are bonded to another atom

4. Four Classes of Elements Noble Gases outermost s, p filled do not react Representative Elements outermost s or p only partially filled

5. Transition Metals outermost s filled adding e - to d sublevel Inner Transition Metals outermost s sublevel is filled adding e - to f sublevel

6. Trends in Atomic Size Within Groups: size increases as you move down e - are being added to additional energy levels Within Periods: size decreases left to right because of increase in effective nuclear charge larger # of p + causes atom to “shrink” inner e - shield nucleus

7. Effective Nuclear Charge

8. Trends in Atomic Size

10. Trends in Ion Sizes cation positive ion atom LOSES electron(s) smaller than atoms from which they are made anion negative ion atom GAINS electron(s) larger than atoms from which they are made

11. Relative Sizes of Cations

13. Relative Sizes of Anions

14. Trends in Ionization Energy Within Groups: IE decreases as you move down e - are farther from nucleus e - not held as tightly in larger atoms Within Periods: IE increases from left to right nucleus has greater attraction for e - in smaller atoms

15. Ionization Energy

16. Trends in Ionization Energy

17. Trends in Electronegativity Within Groups: decreases as you move down atoms too large for nucleus to attract e - Within Periods: increases left to right atoms get smaller, easier to attract e -

18. Trends in Electronegativity