Atomic Models, Slides of Experimental Design

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Atomic Models

Chapter 5

John Dalton

• Billiard Ball Model

John Dalton – English Chemist – 1803

Dalton’s postulates

3. Interpret Diagrams

How does a mixture of atoms of different elements differ

• Dalton’s postulates are illustratedfrom a compound?

below.

Self-check:

-^

To demonstrate that you understand theconclusions used in the development of modernatomic theory, identify the statement that is NOTpart of Dalton’s postulates.

-^

A

All elements are composed of atoms.

-^

B

Atoms of the same element are alike.

-^

C

Atoms are always in motion.

-^

D

Atoms that combine do so in simple whole-

number ratios.

Self - check

To show that you understand the

experimental design used in thedevelopment of atomic theory, summarizethe evidence used by Thomson to arguethat cathode rays consist of negativelycharged particles.

3. Rutherford Nuclear model – (1911) -

center is a positively - charged nucleus (ex:

peach)

Self-check

Compare Rutherford’s expected outcome of

the gold-foil experiment with the actualoutcome to show that you understandexperimental design used in thedevelopment of modern atomic theory.

Self-check

Demonstrate that you understand the

conclusions used in the development ofmodern atomic theory by describing theevidence that led Rutherford to concludethat an atom is mostly empty space.

Self-check

-^

Fill in the blanks to show that you understandthe experimental design used in thedevelopment of modern atomic theory: “According to Bohr’s atomic theory, theatomic emission spectrum of hydrogen resultswhen atoms of hydrogen emit ____________ as____________ move from a ____________energy level to a ____________ energy level.”

Self-check

•^

To demonstrate that you understand the conclusionsused in the development of modern atomic theory,identify how Bohr’s nuclear atom differs fromRutherford’s nuclear atom.

-^

A

Bohr’s model proposed that electrons occupy orbits

of different shapes.

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B

Rutherford’s model explained the physical and

chemical properties of elements, whereas Bohr’s modelonly explained the physical properties.

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C

Bohr’s model states that electrons occupy orbits with

fixed energy levels.

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D

In Bohr’s model, electrons occupy space within a

“cloud” surrounding the nucleus.

Even though the quantum model is the most recent,we still use the Bohr model to illustrate the atom inhigh school chemistry!Some specifics about the Bohr model:The Octet RuleAtoms are most stable when they have 8 electrons intheir outer shell 1

st^

energy level holds 2 electrons 2

nd

energy level holds 8 3

rd

usually holds 8 (to a max of 18) And so on…