Honors Chemistry - Council Rock School District



Arnoldi

Honors Chemistry

Atomic Theory One

Note Sheet Answer Key

|Rutherford Au foil animation | |

|Simulation – electron jumps and falls|

|showing wavelengths given off | |

|Simulation – 2 isotopes of hydrogen –|

|moving model pictures |otopes.shtml |

|Simulation – 2 possible ions of |

|hydrogen |ns.shtml |

|Pictures of atomic spectra and | |

|continuous spectrum | |

|Dalton’s Playhouse – this is so cool | |

|– recreate experiments by Lavoisier, | |

|Priestly, etc. | |

|Prism – splitting colors – beginning | |

|picture of electromagnetic spectrum | |

|A nice picture showing uses of waves | |

|– electromagnetic spectrum | |

|Electromagnetic spectrum – showing | |

|wavelengths | |

|Cathode Ray Tube Movie – short clip | |

|Cathode Ray Tube – Simulation with | |

|Cross | |

| | |

|Dark Side of Moon Album Cover |

| |he+Moon.htm |

| |

| Filling orbital information – diagonal diagrams, K-Q shells, etc. Very|

|comprehensive |

| |

| - orbital notation practice – filling Aufbau diagram |

| |

| pictures of orbitals |

| |

| coolest pictures of atomic orbitals |

| |

| everything about atomic theory |

Useful Diagrams: 4.2, 4.4, 4.5, 4.7, 4.10 and tables 4.1, 4.3

I. Atomic Theory Background Information (4.1)

A. What is an atom?

1. ____________ are the fundamental building blocks of matter.

2. An atom is the ______________________ that still retains the properties of that element.

3. Can we see atoms? Individual atoms are observable with instruments …

B. Important Definitions

1. _______________ (Z): # of protons in the nucleus

a. Always a _________ number, on the periodic table.

(the PT is arranged by atomic number)

b. Atomic number controls the ________________.

(the identity of the atom is based on the

number of protons in the atom)

2. _____________ : the sum of the protons and neutrons in the nucleus

This number is rounded from atomic mass due to the fact that there are isotopes. It is _____ on the Periodic Table.

3. Subatomic Particles:

a. Atoms are made up of ________________________

b. Table

|Particle |Charge |Mass (Two Ways) |Location in Atom |

| | |1 amu |In Nucleus |

|Proton |+ |1.67 X 10-24 grams | |

| | | |In Orbitals |

|Electron |- |Negligible |(outside of nucleus) |

| | | | |

|Neutron |neutral |1 amu |In Nucleus |

*Nucleons:

( __________ and __________ )

#Electrons control the __________ of the particle

__________: negatively charged particles

because electrons were __________

__________: positively charged particles

because electrons were ___________

c. Quarks

(i) Make up protons and neutrons.

(ii) Six Types

up, down, beauty, truth, charmed, strangeness

up = +2/3 charge

down = - 1/3 charge

EX: 2 ups, 1 down = +1 charge ( proton

2 downs, 1 up, = no charge ( neutron

d. Other simpler particles: baryons, mesons, leptons, omega particles

4. _________: atoms of the same element with different masses (because they have different numbers of neutrons)

a. Hydrogen Isotopes

|Hydrogen Isotopes |Protium |Deuterium |Tritium (artificial and radioactive) |

|Protons |1 |1 |1 |

|Neutrons |0 |1 |2 |

|Electrons |1 |1 |1 |

|Mass |1 amu |2 amu |3 amu |

|% Abundance |99.85% |.15% |0% |

b. Some isotopes occur naturally. Most isotopes are produced ______________.

c. Counting protons, electrons, and neutrons:

12 12

Carbon – 12 C or C

6

Carbon / C is the identity of the element.

____ is the mass number.

____ is the atomic number.

Mass # = ________________

(Neutrons = mass # - protons)

Protons = atomic number (see ____________)

Electrons = _________ (unless the atom is charged)

+ Charge indicates the ________ of an electron

- Charge indicates the ________ of an electron

|Isotope |Protons |Electrons |Neutrons |

| | | | |

|40K+1 | | | |

| | | | |

| |12 | |12 |

| | | | |

| |38 |36 |53 |

| | | | |

| |9 |10 |10 |

| | | | |

|14C | | | |

| | | | |

|S-2 | | | |

COMPLETE PROMPT ONE NOW.

COMPLETE PROMPT TWO NOW.

6. Atomic Mass: the average mass of the isotopes of an element

a. In the Past

Originally, _________ was the basis of all atomic masses and was given the mass of 1.0. Later, chemists changed the standard to ________ being 16.000 (which left H = 1.008). In 1961, chemists agreed that ____ is the standard upon which all other masses are based.

1/12 of the mass of 1 atom of 12C = _______

b. Today we know … It’s the ___________ of the isotopes:

75% 35 Cl and 25% 37 Cl

c. Equation

Average atomic mass = [(% abundance)(mass of 1st isotope)]

+ [(% abundance)(mass of 2nd isotope)]......

100

OR

Average atomic mass = [(% abundance)(mass of 1st isotope)]

+ [(% abundance)(mass of 2nd isotope)]......

(with percent as a decimal number)

EXAMPLES: What is the atomic mass for element B?

11B = 80.20% 10B = 19.80%

Find the %’s of 2 isotopes of Carbon given the following information:

average atomic mass = 12.0111

isotope 1 = 12 C

isotope 2 = 13 C

Antimony consists of two naturally occurring isotopes: Antimony-121 has a 57.2500% abundance and an exact mass of 120.9038 amu. What is the percent abundance and exact mass of the other isotope?

E. Particle Accelerators

Miles long. Contain magnets that propel particles along the chamber. The particles smash into each other at high speeds. This results in nuclear disintegration.

Discuss with your partner the atomic mass calculations. Think about both the easy and more complicated questions.

COMPLETE PROMPT THREE NOW.

II. Early Atomic Theories (4.1)

A. First thoughts about matter:

1. Matter is considered to be __________________.

2. This is called the ________________________.

B. Democritus:

1. 460 BC, Greek

2. First person to use the term “______”, which means __________.

3. He also thought atoms were ______ and _____________.

4. Creates the __________________________ – matter is NOT

one continuous piece.

C. 18th Century (1700s)

1. ______________________ appears to support the ideas of atoms.

2. Antoine Lavoisier

a. French, 1770s

b. Law of Conservation of Mass (see chapter two)

3. Joseph Proust

a, French, 1799

b. ____________________________

The fact that a chemical compound contains the elements in exactly the same proportions by mass, regardless of the size of the sample or source of the compound.

D. John Dalton

1. English, 1803

2. ________________________

If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element, combined with a certain mass of the first element, is always a ratio of small whole numbers.

EX: 2 H + 1 O yields H2O

2 H + 2 O yields H2O2

3. Combining the three laws above, Dalton created four statements of Atomic Theory:

a. All matter is made up of ______ which are __________ and _______________.

b. Atoms of the same element are _________ – in particular their __________ are the same. Atoms of different elements are ___________ different, in particular their _________ are different.

c. Atoms combine in ______________________ to form compounds.

d. Chemical reactions are the result …

4. What part of Dalton’s theory do we still believe?

a. Matter _____ made of atoms.

b. Atoms ______________ in simple whole number ratios.

c. Chemical reactions _____________ of the separating or combining of atoms.

5. What part of Dalton’s theory do we not believe?

a. Atoms are ______________ – subatomic particles, and ________________– nuclear reactions (can create atoms in nuclear reactions, also).

b. Atoms of different elements ____________________, and _______________________ can have different masses – isotopes.

12C vs. 13C 14C vs. 14N

6. Model – Billiard Ball

COMPLETE PROMPT FOUR NOW.

III. Developing Atomic Theories (4.2)

A. William Crookes

1. 1870s, English physicist

2. Studied the behavior of gases in vacuum tubes.

(__________________)

3. Crookes’ tubes were the forerunners of picture tubes in TVs.

4. Crookes theorized that some kind of radiation or particles were traveling from the cathode across the tube. He called them cathode rays.

X

[pic]

B. J.J. Thomson

1. 1890s, English

2. Used Crookes tube to discover the electron. (1897)

3. Determined the electron had a negative charge by bending the ray in the Cathode Ray tube using + and – fields.

a. The ray bent __________ the positive field.

b. The ray bent __________ the negative field.

c. Likes _________. Opposites _________.

4. Model – Plum Pudding

C. Thomson and Milliken (combining data)

Oil Drop Experiment

a. Discovered the mass of the electron to be 9.11 X 10-28

grams – nearly negligible. This can also be expressed as

1/1837 amu. (protons and neutrons have a mass of 1 amu)

b. The charge is 1.602X10-19 coulumb – this is the smallest charge ever detected.

D. Eugene Goldstein

1. 1886

2. Found evidence for the proton.

E. Rutherford

1. 1911, New Zealand

2. Gold Foil Experiment – The Discovery of the Atomic Nucleus

a. Diagram

[pic]

b. Description

Rutherford bombarded gold foil with ___________

Most of the particles _____________. A few were

__________. Since alpha particles are _________, they must have hit something positive inside of the atom

(likes repel).

c. Conclusions

(i) There is a ________________________ center

in the atom.

(this is the nucleus)

(ii) The atom is _________________.

(iii) The bulk of the mass of the atom is in the center.

(iv) Electrons are where? _______________, occupying most of the volume of the atom.

*If electrons are negative, and the center

of the atom is positive, why aren’t they

attracted to the center of the atom?

Electron placement is Rutherford’s big flaw.

d. Analogy: if an atom is the size of the Eagle’s stadium, then the nucleus is the size of a tennis ball floating in the middle of the stadium.

E. James Chadwick

1. 1932

2. Confirmed the existence of the ______ by bombarding beryllium atoms with alpha particles.

4 9 12

He + Be C +

2 4 6

Discuss with a partner the discovery of the electron, atomic nucleus and neutron.

COMPLETE PROMPT FIVE NOW.

F. Niels Bohr (Chapter 5)

1. Electrons reside in __________________, aka energy shells.

2. The energy of the level ___________ as the distance from the nucleus increases. ( _______________ )

3. Electrons fill the energy levels from the ____________, or from low to high energy.

4. Bohr Diagrams give us a quick look at how the electrons are

arranged.

a. Basic Pattern shows the _____________ number

of electrons allowed in the first

three levels

)2e- )8e- )8e-

b. Examples

(i). Sodium Atom

(ii). Sodium Ion (+1)

(iii). Chlorine Atom

(iv). Chlorine Ion (-1)

5. Ground vs. Excited States

a. definitions

(i) _____ State fill the first shell, before moving to the second, the second before moving to the third, etc. The last shell (the outermost shell) may or may not be filled. The inside shells must be

all be filled.

(ii) _____ State an inside shell is NOT filled before moving to the next shell

b. AKA

(i) _________ State (ground)

(ii) _________ State (excited)

6. Other Definitions

a. _________ an exact amount of energy

b. ___________ plural of quantum

c. __________ light energy

7. Moving From One Shell to Another – to move from one energy level to another, you must ______________________ amount of energy between those two levels

COMPLETE PROMPT SIX NOW

G. Comparing Modern Atomic Theory to Dalton’s Atomic Theory

1. Similarities matter _____ composed of atoms

atoms _____ combine in simple whole number ratios

2. Differences atoms are divisible (___________________)

(_______________________________)

atoms are destructible (_______________)

(__________________)

atoms of the same element sometimes have

different masses and atoms of different

elements sometimes have the same mass

(_____________)

Technology and Society: In 1931, Ernst Ruska and Max Knoll built the first

electron microscope. It uses an electron beam and “lenses” that consist of magnetic or electric fields. Objects can be magnified over 100,000 times and projected on to a monitor. Biochemistry, Microelectronics, and Biology all use this technology.

NIB Technology, and Society: The mass spectrometer

the mass spec (chemist lingo) is used to detect, analyze, and identify unknown chemicals samples are vaporized, bombarded with electrons (in order to create + ions [positively charged particles due to a loss of 1 electron]), and placed in electrical and magnetic fields.

Due to differences in mass ( # of neutrons) the paths of the molecules curve based on their individual mass. Heavier particles curve less. This change in curvature causes the particles to land on different places on a detector.

The mass spectrometer was invented in 1912. By 1922 it was discovered that there were 300 naturally occurring isotopes that existed out of the 92 elements known at that time.

Used for identifying components of mixtures, analyzing pollution, and dating works of art.

IV. Nuclear Chemistry

A. Definitions

1. __________ Spontaneous disintegration in which small particles of matter (alpha or beta particles) and /or electromagnetic radiation (gamma rays) are emitted by unstable atomic nuclei

2. ____________________ a form of energy that exhibits wavelike behavior as it travels through space

3. _________ the time it takes for a sample of radioactive matter to decay to half its original size

B. Types of Radiation

1. Alpha Particles

a. Positive Helium Atom

b. Symbol

c. Example Equation (the discovery of the neutron)

4 9 12 1

He + Be ( C + n

2 4 6 0

2. Beta Particle

a. Electron

b. Symbol

c. Example Equation

234 234 0

Th ( Pa e

90 91 -1

3. Gamma Ray

a.

b. Symbol

C. Half-Life Examples

1. How much is left?

A radioactive sample with a mass of 15 grams and a half-life of two minutes is left alone for 10 minutes. How much of the sample remains after this time?

2. How much did you start with?

A radioactive sample of matter has a mass of 540 g today. Its half- life is 7 years. How much did it weight 35 years ago?

3. How old is it?

A radioactive sample of Carbon-14 has a half-life of 5700 years. A sample that began with 100 grams now contains 25 grams. How old is it?

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# of Neutrons and Protons

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