VALENCE ELECTRONS AND IONS CHAPTER 5 CONTINUED Subatom

VALENCE ELECTRONS AND IONS CHAPTER 5 CONTINUED

Subatom ic Particle Char ge Mass Location in atom Other Information Protons + 1 AMU nucleus # does not change / defines element Neutrons 0 1 AMU nucleus # can change (isotope) / alters the mass Electrons - 0 AMU shell/cloud # can change (ion) / determines how it will react

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

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

How many valence electrons? Oxygen Tin Tellurium Lithium Selenium

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

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.

How many valence electrons? Oxygen Tin Tellurium Lithium Selenium

Shortcut! EXCEPTION = group number 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.

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

Ionization Cation Anion

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

Cation = ion with a positive charge because it lost one or more electron(s) Lithium Magnesium Aluminum

Anion = ion with a negative charge because it gained one or more electron(s) Chlorine Sulfur Phosphorous