electron shell model

different electrons on different atoms have different energies.

the lower the electron energy, the more stable. He Ne Ar Kr Xe Rn atomic number Li Na H K Rb Cs Fr electron energy (eV)

the noble gases have the lowest electron energies. They are the most stable. the alkali metals have the highest electron energy. They are the most reactive.

He Ne Ar Kr Xe Rn atomic number Li Na H K Rb Cs Fr electron energy (eV) electron energies look to go in cycles or periods the lower the electron energy, the more stable the unreacted element.

explanation: electron shell model electrons in different periods occupy different shells and have different energies.

potential energy PE = C q+q-q+q- r r r PE q+q+ q-q- graph of Coulombic potential energy value of potential energy caused by the two charged particles q + and q -

completely filling a shell is energetically very stable. the noble gases are the most stable. starting a new shell is energetically very unstable. the elemental alkali metal atoms are the most reactive. krypton(4 th )shell argon (3 rd )shell neon (2 nd )shell helium (1 st ) shell

stable electron counts

filled shells and stable Review

He Ne Be B C N O F filled shells are stable Li

He Li Ne Be B C N O F filled shells are stable number of protons in atom is fixed, but electrons can be added or taken away

He Li Ne Be B C N O F filled shells are stable number of protons in atom is fixed, but electrons can be added or taken away take 1 e - from Li or 2 e - from Be

He Li + Ne Be 2+ B C N O F filled shells are stable number of protons in atom is fixed, but electrons can be added or taken away take 1 e - from Li or 2 e - from Be and atom becomes stable

He Li + Ne Be 2+ B C N O F filled shells are stable number of protons in atom is fixed, but electrons can be added or taken away take 1 e - from Li or 2 e - from Be and atom becomes stable add 1 e - to F or 2 e - to O and atom becomes stable

He Li + Ne Be 2+ B C N O 2- F-F- filled shells are stable number of protons in atom is fixed, but electrons can be added or taken away take 1 e - from Li or 2 e - from Be and atom becomes stable add 1 e - to F or 2 e - to O and atom becomes stable

Does O need to gain or lose electrons? How many? Does F need to gain or lose electrons? How many? Does Se need to gain or lose electrons? How many? Does I need to gain or lose electrons? How many? Does N need to gain or lose electrons? How many? Does Al need to gain or lose electrons? How many?

ionic and covalent bonds

two ways to achieve filled shells in chemistry 1) the gifting of electrons 2) the sharing of electrons Li F Li + F-F- + + O O O2O2 + sharing is making a covalent bond gifting is called oxidation, receiving is reduction

two ways to achieve filled shells in chemistry 1) the gifting of electrons 2) the sharing of electrons gifting is called oxidation, receiving is reduction sharing is making a covalent bond Li + F → Li + + F - O + O→ O 2

two ways to achieve filled shells in chemistry 1) the gifting of electrons 2) the sharing of electrons Li + F → Li + + F - → LiF O + O→ O 2 cations and anions coming together is called making an ionic bond

two ways to achieve filled shells in chemistry 1) the gifting of electrons 2) the sharing of electrons Li + F → Li + + F - → LiF O + O→ O=O cations and anions coming together is called making an ionic bond for covalent bond, each line stands for one pair of shared electrons

Does O need to gain or lose electrons? How many? Does F need to gain or lose electrons? How many? Does Se need to gain or lose electrons? How many? Does I need to gain or lose electrons? How many? Does N need to gain or lose electrons? How many? Does Al need to gain or lose electrons? How many?

What stable compound can Na and F make? What stable compound can Cs and Cl make? What stable compound can Ca and O make? What stable compound can Na and O make? What stable compound can Al and F make? What stable compound can Al and O make?

O=O 3 ways of saying the same thing Lewis structure of O 2 O2O2 shell picture

O=O 3 ways of saying the same thing Lewis structure of O 2 O2O2 valence shell picture O O

CO 2 NH 3 H2OH2O CH 4 Lewis structures Please draw the valence shell pictures for all four of these molecules.