VALENCE

ELECTRONS

AND IONS

CHAPTER 5 CONTINUED

Subatomic

Particle

Charge 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 chargeBecause #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?

Tin

Oxygen

Selenium

Tellurium

Lithium

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?

Tin

Oxygen

Selenium

Tellurium

Lithium

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.

IONSatoms 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 Anion

Ionization

Lose 1 e- Gain 1 e-

+1 charge -1 charge-1 charge

What ions do they form?

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)

PhosphorousSulfurChlorine