Electrons

Chemistry

Dr. May

Atomic Inventory

• Protons (Atomic Number)

• Neutrons (Atomic Mass minus Protons)

• Electrons (Same number as protons)

Atomic Particles

Particle Location Mass in

amu

Charge

Proton

Neutron

Electron

nucleus

nucleus

cloud

1

1

0

+ 1

0

1

Electron Function

• Only the electrons of an atom are involved in chemical reactions

• Only the electrons in the outermost orbital are involved in chemical reactions

Outermost Electrons

• Atoms have between 1 and 8 electrons in the outermost orbital

• These electrons are called valence electrons

• Only valence electrons are involved in chemical reactions

Electron Distribution and Configuration

Atom 1s 2s 2p 3s 3p 4sCa - 40 EC 1s2 2s2 2p6 3s2 3p6 4s2

Electron Configuration

• Krypton– 1s22s22p63s23p64s23d104p6

• Sodium– 1s22s22p63s1

• Chlorine– 1s22s22p63s23p5

Reading Electron Configurations

• Krypton - 1s22s22p63s23p64s23d104p6

• The large numbers are the orbitals and in the known elements can go from 1 to 7

Reading Electron Configurations

• Krypton - 1s22s22p63s23p64s23d104p6

• The letters s,p,and d represent the suborbitals

• The fourth letter f is not used in Kr

Suborbitals

• The suborbitals (s,p,d and f) are named after lines in the electromagnetic spectrum:

s = sharp

p = principle

d = diffuse

f = fundamental

Metal Salts Burning

Reading Electron Configurations

• Krypton - 1s22s22p63s23p64s23d104p6

• The superscript or exponent (2p6) represents the number of electrons in each suborbital

• Kr has 6 electrons in the 2p

Valence Electrons

• Krypton - 1s22s22p63s23p64s23d104p6

has 8 valence electrons• Sodium - 1s22s22p63s1

has 1 valence electron• Chlorine - 1s22s22p63s23p5

has 7 valence electrons

Element 118

• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f146d107p6

• Element 118 (ununoctium) (Uuo)• Has 118 electrons• Has 8 valence electrons• Is an inert gas• Was discovered at Berkley in 1999

Valence ElectronsSum of the outermost s an p electrons

• Na = 1

• Ca = 2

• Al = 3

• C = 4

• N = 5

• O = 6

• Cl = 7

• Ne = 8

Oxidation NumberNumber of valence electrons lost (+) or gained (–)

during a chemical reaction

• Na = (1) +1

• Ca = (2) +2

• Al = (3) +3

• C = (4) +4 or –4

• N = (5) +5 or –3

• O = (6) –2

• Cl = (7) –1

• Ne = (8) 0

Distribution Of Sodium

atom 1s 2s 2p 3s 3p 4s

Na - 11

Distribution Of Sodium Ion

ion 1s 2s 2p 3s 3p 4s

Na+1 X

Distribution Of Chlorine

atom 1s 2s 2p 3s 3p 4s

Cl - 17

Distribution Of Chloride Ion

ion 1s 2s 2p 3s 3p 4s

Cl 1

Opposite Charges Attract

The End

• This presentation was created for the benefit of our students by the Science Department at Howard High School of Technology

• Please send suggestions and comments to rmay@nccvt.k12.de.us