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
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