atomic structure

orbital shells

• consists of electrons

• 7 orbital shells (K-Q)

• reveals how an atom chemically reacts

• represents different Electron Binding Energies

• outer shell - valence shell

electron binding energy

• strength of attachment of electron to nucleus

• energy required to completely remove an electron from the atom

• the close to nucleus, the higher the Eb

inner shell

• higher Eb

• difficult to remove (needs more energy)

outer shell

• lower Eb

• easier to remove (needs less energy)

centrifugal

• maintains electron distance from nucleus

• flying out from the center

centripetal

• keeps electrons in orbit

• center-seeking

neutral atoms

have the same number of electrons and protons

ionized atoms

have an unequal number of electrons and protons

neutral

an atom’s normal state is

electrons

primarily determine chemical behavior

protons

primarily determine chemical identity

chemical identity

protons primarily determine

chemical behavior

electrons primarily determine

periods

• rows

• # of occupied electron shells

• atomic number increases from left to right

groups

• columns

• # of valence electrons

• similar chemical properties

octet rule

• states that atoms tend to gain, lose, or share electrons to achieve eight electrons in their outermost shell

• a full valence shell is generally more stable and lower in energy

• the outer shell is limited to eight electrons

transitional elements

• starts at 4th period

• renowned for conducting electricity and heat efficiently

• breaks the orderly progression of shell filling (instead of completely filling the current shell, it fills the next shell)

atomic number

number of protons

atomic weight

weighted average mass of all isotopes

atomic mass/mass number

number of protons + neutrons

atomic mass unit

unit of mass used for expressing atomic and molecular weights