The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the...

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The Atom The Atom Chapter 3 Chapter 3

Transcript of The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the...

Page 1: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

The AtomThe Atom

Chapter 3Chapter 3

Page 2: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

From Idea to TheoryFrom Idea to Theory

DemocritusDemocritus, Greek philosopher, 400 , Greek philosopher, 400 B.C., introduced the concept of an B.C., introduced the concept of an atom, an atom, an ‘indivisible’ particle‘indivisible’ particle..

Page 3: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Basic Laws of MatterBasic Laws of Matter

Law of Conservation of Mass-Law of Conservation of Mass- mass mass can’t be created or destroyed during can’t be created or destroyed during ordinary chemical rxns and physical ordinary chemical rxns and physical changes. changes. Carbon + oxygen Carbon + oxygen carbon dioxide carbon dioxide

12 g12 g 32 g 44 g 32 g 44 g

Page 4: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Law of Definite Proportions- Law of Definite Proportions- a a certain cmpd will always have the certain cmpd will always have the same proportion of each element, by same proportion of each element, by mass and by atoms.mass and by atoms. Ex. Carbon dioxide always has one Ex. Carbon dioxide always has one

carbon atom to 2 oxygen atoms OR 12 carbon atom to 2 oxygen atoms OR 12 g carbon and 32g oxygeng carbon and 32g oxygen

Page 5: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Basic Laws of MatterBasic Laws of Matter

Law of Multiple Proportions-Law of Multiple Proportions- more more than one cmpd can be formed from than one cmpd can be formed from the elements by having a different the elements by having a different whole number ratio of the atomswhole number ratio of the atoms Ex. CO, COEx. CO, CO22

Page 6: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Dalton’s Atomic TheoryDalton’s Atomic Theory

1.1. All matter is composed of All matter is composed of small small particles called atoms.particles called atoms.

2.2. Atoms of the same element are the Atoms of the same element are the same physically and chemically.same physically and chemically.

Page 7: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

3. Atoms can’t be 3. Atoms can’t be divided, created, or divided, created, or destroyeddestroyed..

4. Atoms of different elements combine in 4. Atoms of different elements combine in whole-number ratios to form cmpdswhole-number ratios to form cmpds..

5.5. In chemical rxns, atoms are In chemical rxns, atoms are combined, combined, separated, or rearrangedseparated, or rearranged..

Section Review p69Section Review p69

Page 8: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Structure of AtomStructure of Atom

Atom- Atom- smallest particle of an smallest particle of an element that retains the chemical element that retains the chemical properties of that elementproperties of that element..

Page 9: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Subatomic particles:Subatomic particles: Nucleus- Nucleus- center of atomcenter of atom Proton- Proton- Positively charged particle in Positively charged particle in

nucleusnucleus Neutron- Neutron- neutral particle in nucleus, a neutral particle in nucleus, a

tiny bit larger than protontiny bit larger than proton Electron- Electron- negatively charged particle, negatively charged particle,

about 2000X smaller in mass that about 2000X smaller in mass that protonproton

Page 10: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Cathode Ray TubeCathode Ray Tube

Cathode Ray tube experiment by Cathode Ray tube experiment by JJ JJ ThomsonThomson discovered the discovered the electronelectron (See pg. 70)(See pg. 70)

Page 11: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Conclusions from Experiment:Conclusions from Experiment:

1. Rays cast shadow on other end of tube- 1. Rays cast shadow on other end of tube- lightlight

2. Rays push paddle along- 2. Rays push paddle along- some form of some form of mattermatter

3. Rays deflected by magnet- 3. Rays deflected by magnet- not lightnot light

4. Rays deflected by negative charge- 4. Rays deflected by negative charge- therefore cathode rays are made up of therefore cathode rays are made up of negatively charged particles called negatively charged particles called electrons.electrons.

Page 12: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Discovery of NucleusDiscovery of Nucleus

Robert MillikanRobert Millikan determine the mass determine the mass of an electron to be 9.109 X 10of an electron to be 9.109 X 10-31-31 kg. kg. Since atoms are Since atoms are neutralneutral, atoms must , atoms must have have positivepositive charge. charge.

Ernest Rutherford’s Ernest Rutherford’s Gold Foil Gold Foil ExperimentExperiment discovered the discovered the nucleusnucleus. . See pg. 73See pg. 73

Page 13: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Gold Foil ExperimentGold Foil Experiment

Conclusion of Gold Foil ExperimentConclusion of Gold Foil Experiment1. Most of the alpha particles passed 1. Most of the alpha particles passed through – through – atom mostly empty spaceatom mostly empty space..2. Few deflected and reflected alpha 2. Few deflected and reflected alpha particles - particles - small, dense, small, dense, positive, nucleus in atompositive, nucleus in atom

Note: Note: nuclear forcesnuclear forces hold neutrons hold neutrons together in the nucleus.together in the nucleus.

Section Review p74Section Review p74

Page 14: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Counting AtomsCounting Atoms

Atomic number- Atomic number- number of protons number of protons in nucleus of an atomin nucleus of an atom. . Number of Number of protonsprotons in the nucleus determines in the nucleus determines which element it is. which element it is. Ex. All C atoms have 6 protons. No Ex. All C atoms have 6 protons. No

other element has 6 protons. Locate other element has 6 protons. Locate the atomic number of carbon on the the atomic number of carbon on the periodic tableperiodic table

Page 15: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

IsotopesIsotopes Isotopes- Isotopes- atoms of the same element atoms of the same element

with different number of neutronswith different number of neutrons, , so their masses are different. so their masses are different. Isotopes of the same element are Isotopes of the same element are chemically differentchemically different

Page 16: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Ex. 3 forms of hydrogenEx. 3 forms of hydrogen

1. Protium- 1. Protium- one proton, no neutronsone proton, no neutrons – 99.985% – 99.985% in naturein nature

2. Deuterium- 2. Deuterium- one proton, one one proton, one neutronneutron – – 0.015% in nature0.015% in nature

3. Tritium- 3. Tritium- one proton, two neutronone proton, two neutron – – radioactive- very little in nature, radioactive- very little in nature,

can be madecan be made

Page 17: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Counting AtomsCounting Atoms Mass number- Mass number- number of protons and number of protons and

neutrons in the nucleus of an isotopeneutrons in the nucleus of an isotope Ex.Ex.

Protium’s mass number is Protium’s mass number is 11 (1p + (1p + 0n), 0n), hydrogen-1hydrogen-1 (hyphen (hyphen notation), nuclear notation), nuclear symbol =symbol =Deuterium’s mass number is Deuterium’s mass number is 22 (1p + (1p + 1n),1n),

hydrogen-2hydrogen-2, nuclear symbol =, nuclear symbol =Tritium’s mass number is Tritium’s mass number is 33 (1p +2n), (1p +2n),

hydrogen-3hydrogen-3 , nuclear symbol = , nuclear symbol =

Page 18: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

PracticePractice

1. How many protons, electrons, and 1. How many protons, electrons, and neutrons are in chlorine-37?neutrons are in chlorine-37?

Practice p78Practice p78

Page 19: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Atomic Mass Atomic Mass

Mass of one atom of carbon-12 is Mass of one atom of carbon-12 is 12 12 amu (atomic mass unit).amu (atomic mass unit). So all atomic So all atomic masses use C-12 as standard.masses use C-12 as standard.

Average atomic mass of an element is Average atomic mass of an element is the the weighted average of all the weighted average of all the naturally occurring isotopes of that naturally occurring isotopes of that elementelement The average atomic mass depends on the The average atomic mass depends on the

mass and abundance of each element’s mass and abundance of each element’s isotope.isotope.

Page 20: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Atomic Mass Atomic Mass CalculationsCalculations

1.1. Calculate the average atomic mass Calculate the average atomic mass of copper given the following of copper given the following abundances and atomic masses for abundances and atomic masses for each isotope.each isotope.

Isotope 1: 62.929598 amu and Isotope 1: 62.929598 amu and 69.17%69.17%

Isotope 2: 64.927793 amu and Isotope 2: 64.927793 amu and 30.83%30.83%

Page 21: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

What is the mass of one aluminum What is the mass of one aluminum atom? One gold atom? One neon atom? One gold atom? One neon atom?atom?

Page 22: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Mass to Number of AtomsMass to Number of Atoms

1 mole = 1 mole = 6.02 X 106.02 X 102323 particles particles = = Avogadro’s numberAvogadro’s number

Molar Mass = Molar Mass = number of grams of number of grams of one mole of a substanceone mole of a substance

Practice: What is the molar mass of Practice: What is the molar mass of each element? He, Li, Hgeach element? He, Li, Hg

Page 23: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Mass and MolesMass and Moles

1.1. What is the mass in grams of 3.50 What is the mass in grams of 3.50 moles of copper?moles of copper?

2. How many moles of aluminum are 2. How many moles of aluminum are in 11.9 g?in 11.9 g?

Practice p83Practice p83

Page 24: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Moles to AtomsMoles to Atoms

3. How many moles of silver are 3.01 3. How many moles of silver are 3.01 X 10X 1023 23 atoms of silver?atoms of silver?

4. How many atoms of tungsten make 4. How many atoms of tungsten make up 1.34 X 10up 1.34 X 10-2-2 moles? moles?

Page 25: The Atom Chapter 3. From Idea to Theory Democritus, Greek philosopher, 400 B.C., introduced the concept of an atom, an ‘indivisible’ particle. Democritus,

Atoms to MassAtoms to Mass

5.5. What is the mass in grams of 7.5 X What is the mass in grams of 7.5 X 10101515 atoms of nickel? atoms of nickel?

6.6. How many atoms of sulfur, S, are in How many atoms of sulfur, S, are in 4.00 g of sulfur?4.00 g of sulfur?

7. What is the mass of 3.10 X 107. What is the mass of 3.10 X 102323 atoms of Cl?atoms of Cl?