Download What does an atom look like?

What does an atom look like?
Date
Event / Scientist
400 B.C.
Democritus
(Pg. 67)
1808
John Dalton
(Pg. 68-69)
Description / Significance

A philosopher (not a scientist) who stated: nature’s basic particle is called an
____________ meaning __________________.
The First Atomic Theory (experimented & concluded)
1. All matter is composed of extremely small particles called _______________.
2. Atoms of the same element are identical; whereas, different element’s atoms are
different from each other in _________, _________, & __________ ______________.
3. Atoms cannot be _________________, ____________, or ________________.
4. Atoms of different elements combine in whole-number ratios to form
_____________________
___________________.
5. Chemical reactions are when atoms are _______________, _________________, or
_____________________.
1897
Cathode Ray Tube
Experiment
(Pg. 72-73)





_____________ ________________ was passed through gases in a glass tube.
The current passed through going from the negative (–) cathode to the positive (+)
_______________.
Observations: the current (cathode rays) were ________________ by a negatively
charged object.
Hypothesis: cathode rays were made of ________________ charged particles.
In 1897, J.J. Thomson concluded that all cathode rays are composed of identical
_______________ charged particles, which were named ___________________.
1909
Robert Millikan
(Pg. 73)
1897
J.J. Thomson
(Pg. 73)

Measured the _____________ of an ________________ through the oil drop
experiment.

Called his model of the atom the _______________ ______________ model.

The ____________ ___________ were spread evenly throughout the ___________
___________ of the rest of the atom.

Similar to seeds in a ___________________ where the seeds are spread throughout.
(Seeds = electrons
flesh of fruit = positive mass)
1911
Gold Foil Experiment
Label the image below using Figure 6 on Pg. 74
Performed by:
___________________
Pg. 74
 Alpha particles have a _______________ charge.
1911
Ernest Rutherford

Alpha particles were expected to pass through atoms of the gold foil with
_____________ deflection, most did.

But instead a few alpha particles had actually been deflected back
______________ the source.
Label the image using Figure 7 on Pg. 75
 A small number of positive alpha particles were _________________ backwards proving
that the nucleus is tiny and positive.
 Most of the particles _______________ through the atom, proving that the atom is
mostly empty space.
Conclusion to the Gold Foil Experiment:
 Each atom contains a ___________, dense, _____________ charged ______________
surrounded by electrons.
1913
Niels Bohr
(Pg. 102)
 Electrons can circle the nucleus only in allowed ____________ or ________________.
 Each orbit has a specific, definite, defined amount of ___________________.
 The electron is in its lowest energy when it is in ___________ closet to the __________.
 This electron orbit at the lowest energy state is separated from the ___________ by a
large empty space where the electron ______________ exist.
 The energy of the electron is ________________ when the electron orbits successively
________________ away from the nucleus.
 The electron orbit is also called the atomic ___________________ level.
 Bohr’s model of the atom is referred to as the planetary model similar to how the
_________________ orbit the sun.
1924
Louis de Broglie
(pg. 104)

Electrons have wave-like properties.

Electron waves can only exist at specific _____________________, which correspond
to specific energies of the electron orbits.
1926
Erwin Schrödinger
(Pg. 106)

Developed a mathematical wave equation that stated: an electron behaves as a wave
and has certain amount of energy.

Electrons do not travel around the nucleus in neat ______________ (disproving Bohr).

Electrons exist in certain regions called ________________ (a.k.a. the electron cloud).
1927
Werner Heisenberg
(Pg. 105)

Heisenberg Uncertainty Principle: it is impossible to simultaneously know both
Quantum Mechanical
Model
(Pg. 106)

Our current model of the atom.

Developed from studies of the electron as both a wave and particle (de Brogile,
_________________ and __________________ of an electron.
Schrödinger, and Heisenberg)

Electrons exist in certain regions called ________________ (a.k.a. the electron cloud).

An ____________ is a three-dimensional region around the ________________ that
indicates the __________________ location of an electron.

Atomic orbitals have different ________________ and ________________.
(Pg. 108)

draw an s orbital

draw a p orbital

draw a d orbital
Building Elements Go to: http://tinyurl.com/ok7eao6
1. Helium: atomic number: ____________
#p+ _________ #e- _________
Indicate the quantity of each orbital that you used to create the atom.
Then draw the atom in the space below.





1s
2s
2p
3s
3p
2. Carbon: atomic number: ____________
#p+ _________ #e- _________
Indicate the quantity of each orbital that you used to create the atom.
Then draw the atom in the space below.





Complete the orbital diagram for helium.
(What you see in the electrons box)
1s
2s
2p
3s
3p
3. Sodium: atomic number: ____________
#p+ _________ #e- _________
Indicate the quantity of each orbital that you used to create the atom.
Then draw the atom in the space below.





Complete the orbital diagram for helium.
(What you see in the electrons box)
1s
2s
2p
3s
3p
Complete the orbital diagram for helium.
(What you see in the electrons box)