CHAPTER 5 CONTINUED

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

+
-

• 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?
Tin
Oxygen
Tellurium
Lithium
Selenium

• 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?
Tin
Oxygen
Tellurium
Lithium
Selenium

Shortcut !
= group number
EXCEPTION
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

Cation
Ionization
Anion

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