November 28th• Take the two worksheets.• Write down your homework• Answer the Quick Write on

the worksheet.

SWBAT:• Summarize each

scientist and philosopher’s addition to the development of the structure of the atom.

Homework:• read pgs 112 - 118

The History of The Atom

• Introduction_to_the_Elements.mov

November 30thQuick Write:• How are electrons kept in

orbit around the nucleus?• What descriptive words can

you use to describe Niels Bohr and his model of the atom?

SWBAT:• Summarize each

scientist and philosopher’s addition to the development of the structure of the atom.

• Explain the forces within an atom.

Homework:• review your notes and highlight key terms and complete the video worksheet

Aristotle Democritus

• Greek philosopher• Believed that there

were only four elements: – water – fire– Earth– air

• Greek philosopher• Believed that matter

cannot be divided into small pieces forever.

• He named the smallest piece an atomos,

• Atomos is Greek for atom.• Atomos means indivisible.• Atom: the building block

of all matter.

The Proposed Atomic Theory, by Dalton

• All elements are composed of atoms. Atoms are indivisible and indestructible.

• Atoms of the same element are exactly alike.• Atoms of different elements are not alike.• Compounds are formed by the joining of atoms of

two or more elements.

Thomson’s Model

• In 1897, Thomson proposed that the atom maybe made of even smaller particles.

• He explained that there were positive charges in the atoms and negative charges scattered throughout.

• ”plum pudding”

Rutherford’s Model

• Conducted an experiment concluding that the atom was mostly empty space filled with positive charges.

• Proposed that the positive charged particles were in the center of the atom, called the nucleus.

• Outside the nucleus were negative electrons scattered throughout the edge of the atom.

Niels Bohr

• In 1913, Bohr believed that the electrons traveled in a definite orbit with a certain energy level and certain distance from the nucleus.

• Each energy level can hold a certain amount of electrons.

• 2-8-18-32-32

December 1stQuick Write:• What are the four forces of

the atom.• Which is the strongest force• What does it act as? Explain

SWBAT:• Identify where each

electron is found according to the Bohr model.

• Draw and identify your mystery atoms!

Homework:• Finish Bohr Model worksheet • Look up the use of each element you identified on your Bohr Model worksheet.• bring in the all completed class work from Tuesday tomorrow.

Modern Atomic Model

• Today we believe that the electrons do not travel a certain path.

• They do have a certain energy level.

• They are always moving

The Bohr Model

• According to the Bohr model each energy level can hold a certain number of electrons.

• Starting from the first level outside of the nucleus:– Level 1: can hold 2 electrons– Level 2: can hold 8 electrons– Level 3: can hold 18 electrons– Level 4: can hold 32 electrons– Level 5: can hold 32 electrons

Look at the examples below:

Secondshell

Helium2He

Firstshell

Thirdshell

Hydrogen1H

2He

4.00Atomic mass

Atomic number

Element symbol

Electron-shelldiagram

Lithium3Li

Beryllium4Be

Boron3B

Carbon6C

Nitrogen7N

Oxygen8O

Fluorine9F

Neon10Ne

Sodium11Na

Magnesium12Mg

Aluminum13Al

Silicon14Si

Phosphorus15P

Sulfur16S

Chlorine17Cl

Argon18Ar

Figure 2.8

Closure

• Draw your samples on the board!

Forces Within

• Electromagnetic force: is an attraction or repulsion between particles.– If the particles have the

same charge they are repelled.

– If the particles have opposing charges they are attracted to each other.

• Strong Force

• Weak Force: • Gravity:

Closure

• Which force is the weakest and why?

• Which two forces keep the atom’s strucutre?