1. VALENCE ELECTRONS AND IONS CHAPTER 5 CONTINUED

2. Subatomic Particle ChargeMassLocation in atom Other Information Protons+1 AMUnucleus# does not change / defines element Neutrons01 AMUnucleus# can change (isotope) / alters the mass Electrons-0 AMUshell/clou d # can change (ion) / determines how it will react

3. Atoms are Neutral = no charge Because #p + = #e -

4. VALENCE ELECTRONS The electrons in the outermost shell The electrons that are involved in bonding The number of valence electrons is important for atom stability – shells “want” to be full

5. How many valence electrons? Tin Oxygen Selenium Tellurium Lithium

6. ATOMS “WANT” TO BE STABLE How do they get stable? By filling their valence shells (outermost shells) – octet rule By being like Noble gases – who do not react with other elements because their valence shells are already full By gaining electron to fill a shell or by losing electrons to get rid of a shell exposing a full one underneath

7. VALENCE ELECTRONS AND LEWIS DOT STRUCTURES We really only need to look at the valence electrons – they are the only ones that interact with the world. So, we use Lewis dot structures.

8. How many valence electrons? Tin Oxygen Selenium Tellurium Lithium

10. EXCEPTION = group number Shortcut ! They all “want” to be stable, which means have a full valence shell. The octet rule says all shells are full with 8 electrons in them, but the exception is when the valence shell is the first shell.

12. IONS atoms that have a charge because they have gained or lost electrons to become stable with a full valence shell Moving electrons changes the charge

13. Cation Anion Ionization

15. Lose 1 e- Gain 1 e- +1 charge -1 charge -1 charge What ions do they form?

16. Cation = ion with a positive charge because it lost one or more electron(s) LithiumMagnesium Aluminum

17. Anion = ion with a negative charge because it gained one or more electron(s) PhosphorousSulfur Chlorine