Chemistry The Atom © SSER Ltd.. Ancient Greeks were the first to come up with the idea of atoms. Democritus Democritus suggested that all matter was made.

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