chemistry the atom © sser ltd.. ancient greeks were the first to come up with the idea of atoms....
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ChemistryChemistry
The AtomThe Atom
© SSER Ltd.
Ancient Greeks were the first to come up with the idea of atoms.
Democritus
Democritus suggested that all matter was made of tiny indivisible particles called atoms. (Greek “atoma”)
John DALTONJohn DALTON
An indestructible “Dalton” atom
Ha Ha! You can’t break me!!!!
J.J. THOMPSONJ.J. THOMPSON
In 1910, Earnest Rutherford carried out experiments in which particles were fired at a thin sheet of gold.
Earnest RutherfordEarnest Rutherford
Rutherford expected all of the particles to pass straight through...
Earnest RutherfordEarnest Rutherford
He concluded that the atom consisted of a central nucleus, which contained most of the atom’s mass, surrounded by the electrons. He also predicted the existence of neutrons in the nucleus.
Ernest RUTHERFORDErnest RUTHERFORD
Ernest RUTHERFORDErnest RUTHERFORD
Rutherford could not explain why the negative electron didn’t fall into the positive nucleus and destroy the atom.
?
Neils Bohr
I think I can help!
Neils BOHRNeils BOHR
He showed that the electrons inhabit discrete energy levels surrounding the nucleus
When the atom was “excited” the electron could “jump” to a higher level.
When the electron came back down, it released energy in the form of light.
Elements emit a particular wavelength or colour as
electrons jump from one shell to another
Elements emit a particular wavelength or colour as
electrons jump from one shell to another
Eg. Neon light
Neils Bohr: 1885 - 1962Neils Bohr: 1885 - 1962
Element 107 on the Periodic Table is called Bohrium (Bh)
The first electron level (shell) can hold up to 2 electrons.
The second electron level (shell) can hold up to 8 electrons.
The third electron level (shell) can hold up to 18 electrons.
Electron Levels (Shells)Electron Levels (Shells)
= Neutron = Proton = Electron
C 12Mass Number
6Atomic Number
The Carbon AtomThe Carbon Atom
6 x 6 x 6 x
= Protons = Electrons= Neutrons
In the 1920’s things changed!
Although Bohr’s idea of energy levels was still accepted, his idea of planetary orbits for electrons was rejected!
REJECT ! !
So……
What’s Next???????????????
Erwin Schrödinger
He proposed the electrons appear as “clouds”.
The electron has a high probability of being located within this cloud or region surrounding the nucleus.
1887-1961
SubshellsSubshells
Each energy level/shell (n) contains one or
more subshells – s, p, d, and f
Each subshell contains an electron orbital
where up to 2 electrons can most likely be
found
Each energy level/shell (n) contains one or
more subshells – s, p, d, and f
Each subshell contains an electron orbital
where up to 2 electrons can most likely be
found
S Orbitals
Three p OrbitalsThree p Orbitals
px py pz
p subshell can hold a maximum of 6 e-’s in p orbitals
p subshell can hold a maximum of 6 e-’s in p orbitals
Timberlake LecturePLUS 2000Timberlake LecturePLUS 2000
d orbitals – max 10e-’sd orbitals – max 10e-’s
H 1s1
He 1s2
Li 1s2 2s1
C 1s2 2s2 2p2
S 1s2 2s2 2p6 3s2 3p4
Writing Electron Configurations
Learning CheckLearning Check
Indicate which configuration is correct for potassium. Explain.
A. 1s22s22p63s1
B. 1s22s22p63s23p6
C. 1s22s22p63s23p64s1
D. 1s22p83s1
E. 1s22s22p63s23p7
Indicate which configuration is correct for potassium. Explain.
A. 1s22s22p63s1
B. 1s22s22p63s23p6
C. 1s22s22p63s23p64s1
D. 1s22p83s1
E. 1s22s22p63s23p7
SolutionSolution
Potassium:
A. 2, 2, 8, 5
B. 2, 8, 3
C. 2, 8, 5
D. 2, 6, 7
Potassium:
A. 2, 2, 8, 5
B. 2, 8, 3
C. 2, 8, 5
D. 2, 6, 7
Learning CheckLearning Check
Using the periodic table, write the complete electronic configuration for each:
A. Cl
B. Sr+2
C. I
Using the periodic table, write the complete electronic configuration for each:
A. Cl
B. Sr+2
C. I
SolutionSolution
Learning CheckLearning Check
A. The final two notations for Co are
1) 3p64s2
2) 4s24d7
3) 4s23d7
B. The final three notations for Sn are
1) 5s25p24d10
2) 5s24d105p2
3) 5s25d105p2
A. The final two notations for Co are
1) 3p64s2
2) 4s24d7
3) 4s23d7
B. The final three notations for Sn are
1) 5s25p24d10
2) 5s24d105p2
3) 5s25d105p2
SolutionSolution
A. The final two notations for Co are
3) 4s2 3d7
B. The final three notations for Sn are
2) 5s2 4d10 5p2
A. The final two notations for Co are
3) 4s2 3d7
B. The final three notations for Sn are
2) 5s2 4d10 5p2
Learning CheckLearning Check
A. Number of electrons in a p orbital1) 1e 2) 1e or 2e 3) 3e
B. Number of orbitals in a p subshell1) 1 2) 2 3) 3
C. Number of orbitals in 4d subshell1) 1 2) 3 3) 5
D. Number of electrons (maximum) in a 3d subshell
1) 2e 2) 5e 3) 10e
A. Number of electrons in a p orbital1) 1e 2) 1e or 2e 3) 3e
B. Number of orbitals in a p subshell1) 1 2) 2 3) 3
C. Number of orbitals in 4d subshell1) 1 2) 3 3) 5
D. Number of electrons (maximum) in a 3d subshell
1) 2e 2) 5e 3) 10e
SolutionSolution
A. Number of electrons in a p orbital
2) 1e or 2e
B. Number of orbitals in a p subshell
3) 3
C. Number of orbitals in 4d subshell
3) 5
D. Number of electrons in a 3d subshell
3) 10e
A. Number of electrons in a p orbital
2) 1e or 2e
B. Number of orbitals in a p subshell
3) 3
C. Number of orbitals in 4d subshell
3) 5
D. Number of electrons in a 3d subshell
3) 10e