Chapter 3 The Atom

HISTORY OF THE ATOM NOTESBLACK CIRCLE ACTIVITY

Day One and Day Two

Black Circles

• You and your partner will be given a black circle.

• Within the black circle is a ball and some barrier

• Your job is to figure out what shape the barrier is….

The Greek Philosophers

Democritus • Greek Philosopher

• Nature must be small particles which were indivisible

Aristotle• Greek Philosopher

• Matter was continuous

• Table (chop forever)

John Dalton

1. Matter = particles with definite size & mass

2. All atoms that make up an element have the same mass.

John Dalton

3. Atoms of 2 different elements have different masses.

4. Atoms come together in definite ratios to form compounds.

H2O

Thomson

• Studied the Cathode Ray Tubes • Rays appear on phosphorescent screen when

an electrical current is sent through • Atoms are neutral • How could the magnet affect these particles? • Must be smaller positive and negative

particles

J.J. Thomson

Rutherford

• Gold Foil Experiment

• What did he expect? – Majority of particles to hit straight across opening

What actually happened?

• Most went through

• Few particles hit foil and bounced back

Conclusions from the Gold Foil Experiment

1. Atom is mostly empty space

2. Mass is concentrated in the center

3. Nucleus is positive

RUTHERFORD MARBLE ACTIVITYDay Three

Rutherford: Measuring what you cannot see

LAB WRITE-UPREVIEW FOR QUIZ

Day Four

Dalton

1. What is the name of his theory?

2. What are elements made of?

3. An atom of hydrogen and an atom of carbon are ________

4. What are compounds made of?

J.J. Thomson

1. What did Thomson discover?

2. What is the charge of an electron?

Rutherford

1. What is the charge of an alpha particle?

2. Why is Rutherford’s experiment called the gold foil experiment?

3. How did he know the atom was mostly empty space?

Rutherford

4. What happened to the alpha particles as they hit the gold foil?

5. How did he know that the nucleus was positively charged?

LECTURE: NUCLIDE SYMBOLSQUIZ: HISTORY OF ATOMIC STRUCTURE Day Five

Structure of the Atom

• Proton – Nucleus – Positive Charged

• Neutron– Nucleus – Neutrally charged

• Electron – Outside the nucleus – Negatively charged

Nuclide Symbols

• Atomic Number

• Mass Number

Nuclide Symbol

• Write the nuclide symbol for a potassium atom that has 21 neutrons.

Lets Try a FewWrite the Nuclide Symbols

• A lithium atom with 4 neutrons

• A sulfur atom with 15 neutrons

Assignment

• Page 20 – Practice Problems: Writing Nuclide Symbols • First Four

LECTURE: NUCLIDE SYMBOLS& ISOTOPES

Day Six

Nuclide Symbols

• Mass Number

• Atomic Number

Lets Try a Few!!

• Write the nuclide symbols for the following:

– Copper- 64

– A Sulfur with has 17 neutrons

– Potassium- 39

Isotopes

• Atoms of the same number of protons but different number of neutrons

Assignment

• Page 20 and 21

Day Seven

LECTURE: NUCLIDE SYMBOLS AND IONS

Nuclide Symbols

Nuclide Symbols for Ions

• What is an ion? – An ion is a charged particle • It could be positive or negative

• What does that do to the number of protons, electrons, and neutrons?

Example

• 40K+1 , Determine the number of protons, neutrons, and electrons.

Lets Try a Few!

• Determine the number of electrons, protons, and neutrons in the following:

• 81Br-1

• 18N-3

Radioactivity

• Three types of Radioactivity – Alpha

– Beta

– Gamma

Assignment

• Page 22– Complete the first table

NUCLIDE SYMBOLS/ RADIOACTIVITY PRE-LAB FLAME TEST

Day Eight

Radioactivity

• Three types of Radioactivity – Alpha

– Beta

– Gamma

Example

Properties of Electrons

• Most of the atom’s mass is made up of ______

• Most of the atom’s volume is made up of _____

• Found in __________

Properties of Electrons

• The closer the electron is to the nucleus the less energy it has

Ground vs. Excited States

Ground State • Close to nucleus as possible

Excited State – Electrons receive energy

move farther away– Release E to drop back down

to ground state (LIGHT) – Light can be seen in different

colors – Elements can be identified by

observing the colors it releases

Assignment

• Radioactivity Worksheet

FLAME TESTREVIEW FOR NUCLIDE AND RADIOACTIVITY QUIZ

Day Nine

QUIZ: NUCLIDE AND RADIOACTIVITY LAB WRITE-UP

Day Ten

ELECTRON CONFIGURATION

Day Eleven

Locating/Mapping Electrons

• Energy Levels (n) – Higher the n farther away from the nucleus– More Energy

• Sublevels – Number of sublevels is related to the energy level – N=1 : 1 sublevel , N=2: 2 sublevels – N= 3 : ? Sublevels , N=4 : ??? , N= 5: ???

Shapes and Orbitals

• Orbital: – Most probable location of the electrons – Each orbital can hold a maximum of 2 electrons

• Shapes – 4 different orbitals that have four different shapes

– s, p, d, f

Lets try to summarize this: (Page 28)

Sublevels (Symbol)

# of orbitals

# of electrons in EACH orbital

TOTAL # of electrons possible in sublevel

s

p

d

f

ELECTRON CONFIGURATION

Day Twelve

Lets try to summarize this: (Page 28)

Sublevels (Symbol)

# of orbitals

# of electrons in EACH orbital

TOTAL # of electrons possible in sublevel

s

p

d

f

Lets dig a little deeper: (Page 28)

Energy Level(n)

# of Sublevels

Type of sublevels

# of electrons possible in each orbital

Total # of electrons possible in Energy Level

1234567

So how do we “map” out the location of the electrons?

• Aufbau Principle: – Electrons will always fill up an atom from lowest to

highest energy

• CARBON

Assignment

• Page 29 – Oxygen, Boron, Helium, Sulfur, Magnesium

ELECTRON CONFIGURATION Day Thirteen

What about the bigger elements?

• Potassium

1s2s 2p

3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f

7s 7p 7d 7f

Assignment

• Page 30 – #1-10

QUIZ: ELECTRON CONFIGURATIONMODEL OF THE ATOM

Day Fourteen

REVIEW FOR TESTMODEL OF THE ATOM

Day Fifteen

TEST Day Sixteen