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Physical Science Chapter 4. Atomic Structure. 4.1 Studying Atoms. Democritus and Aristotle Democritus thought all matter consisted of extremely tiny particles that could not be divided. (Cut aluminum foil in half) - PowerPoint PPT Presentation
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Physical Science Chapter 4
Atomic Structure
Democritus and Aristotle◦ Democritus thought all matter consisted of
extremely tiny particles that could not be divided. (Cut aluminum foil in half)
◦ Also thought matter in liquids was round and smooth; in solids rough and prickly
◦ Aristotle thought there was no limit to the number of times matter could be divided.
4.1 Studying Atoms
Developed a theory to explain why the elements in a compound always behave in the same way.
Main Points◦ 1) All elements are composed of atoms.◦ 2) All atoms of the same element have the same
mass, and atoms of different elements have different masses.
◦ 3) Compounds contain atoms of more than one element.
◦ 4) In a compound, atoms of different elements always combine in the same way.
Dalton’s Atomic Theory
Used a cathode ray tube to show evidence for subatomic, charged particles.
Thomson’s Model
Plum pudding model (chocolate chip ice cream.
Negatively charged particles evenly spaced throughout a solid mass of positive charge.
Thomson continued
The Gold Foil Experiment – Evidence for a nucleus.
Rutherford’s Atomic Theory
Chapter 4Lesson 2
“Structure of the Atom”
A. An atom1. smallest part of matter2. Ripping paper example
B. Areas of an atom1. Nucleus – center of an atom
-holds protons and neutronsa. Protons (P) – positively charged
particle found in the nucleus.-has a mass of 1-has a charge of 1+
I. Subatomic Particles
b. Neutrons (N) – non-charged particle found in the nucleus.
-has a mass of 1-has no charge “0”
2. Electron Cloud – area around the nucleus which contains electrons
a. Electrons (e) – negatively charged particle found outside of the nucleus
-has a mass of 0-has a charge of 1--moves around the outside of the nucleus
Protons ElectronsNeutrons
Particle Mass Charge Location of particle
Particles in an Atom Review
Proton
Neutron
Electron
1
1
0
1+
0
1-
nucleus
nucleus
Electron cloud
A. Def – the # of protons in an atom’s nucleus. 1. Every carbon atom has 6 protons…2. Every neon atom has 10 protons…
B. On P.T. – located right above the chemical symbol
*Protons dictate the type of element we have**Electrons always equal the # of protons*
II. Atomic Number
A. Def – The sum of protons and neutrons in the nucleus of an atom.1. On P.T. – bottom number
-round up/down2. Ex: What is the mass number of the following elements?
Carbon OxygenIron CalciumSodium Zinc
III. Mass Number
12
56
23
16
40
65
3. Mass # = Protons + Neutrons
4. How many Neutrons on average are found in the following elements?Boron FluorineSilicon CopperSilver Gold118
14
6
61
10
35
A. Def – An atom that has a different number of neutrons.1. Does not affect the element2. Only changes the weight of the element
3. Ex: Boron-10 and Boron-11
IV. Isotope
p p p p p p p p p p
n n n n nn n n n n n
5 protons 5 protons
5 neutrons 6 neutrons
This meansthe mass #
Boron-10 Boron-11
4. How many neutrons do the following isotopes have?
Oxygen-14Titanium-50Magnesium-22Potassium-43Aluminum-23Iodine-130
6
28
10
24
10
77
A. Def – average mass of all isotopes of one element combined.1. Found on P.T. underneath chemical symbol.2. Ex: Carbon = 12.011
“Carbon has 3 known isotopes. Carbon-12, 13, and 14. Carbon-12 makes up
99% of all carbon on earth. Carbon-13 and 14 make up 1%.”
III. Average Atomic Mass
Chapter 4Lesson 3
“Modern Atomic Theory”
Chemistry Timeline…pg. 114-115
A. Def – a specific area where an electron is likely to be.
I. Bohr’s Model / Energy Levels
nucleus
2 electrons
8 electrons
18 electrons
32 electrons
e- e-
e-
e-
e-
e-
e-
e-
e-e-
e- e-e-
e-
e-
e-
e-
e-e-
e-
e-
e-e-e-
e-
e-
e-
e-
e-e-
e-
e- e-e-
e-
e-
e-
e-e-e-
e-e-
e-e-
e-e-e-e-
e-e-
e-e-
e-e-
e-
e-
e-e-
e-e-
Energy Level Maximum # of Electrons
1
2
3
4
2
8
18
32
Electrons in Energy Levels
1. Draw a picture of the following atoms with the correct number of e’s, p’s, and n’s…a. Na d. Heb. Al e. Cc. K f. S
2. Assign: Read pg. 118 and 1193. What is the difference between a ground
state and an excited state?
In Class Assignment