Ch 3

Atoms: The Building Blocks of Matter

electron

neutron

proton

Bell Ringer

• What is the modern day idea of what an atom looks like?

• Draw your model and label the parts.

Silent Bell work• In the front of your Comp book write:

– Website for text book: my.hrw.com– Sign on: astudents643– Password: p2p6n

• Go to the above website and log in with your phone to check out the online text book. If you don’t have a phone then just do it when you get to a computer.

• Have your foldable out so I can take a look at its splendid completeness : )

• Get bags and Glue or staple foldable into your comp book and add it to the table of contents.(this is the beginning of unit 2 test)

• Within Your group you need to create a summary of your information. Organize your data so that it is easy to convey to others.

• Who — Person(s) responsible.What’s were they? • What — A description of the discovery and an illustration

of the model. • Where — Country, state, university, etc. • When — Date(s). • Why — The prior knowledge at the time. • How — A summary of the technology or evidence used to

develop the model. • References —two other helpful resources from the

internet.• Your Group will break apart and you will become the

expert for other students.

Building Block of all things?• Atom-Greek meaning-indivisible• Democritus-400 B.C. atom cannot be

broken down into smaller parts• Aristotle-did not believe

in atoms.– He believed in Alchemy.

• He led society astray for 2000

Years before we finally started to

develop the atom we know today.

Democritus

Videos

• J.J. Thomson and Rutherford• https://

www.youtube.com/watch?v=thnDxFdkzZs

Summary of History of the Atom

Democritus-400 BC:

Atom

Aristotle:

Alchemy

Dalton-1808:

5 Assumptions

Thomson-1897:

-Electron

Rutherford-1911:

-electrons around nucleus

-Dense Positive Nucleus

-Lots of empty Space

Bohr-1913:

Electons travel in

Fixed paths• Only Worked for Hydrogen• Didn‘t explain chemical

reactions

1932:

Chadwick:

Neutron

Heisenburg Uncertainty Principal

+

1909: Millikan discovers the size of the charge of the electron.1886: Goldstien

discovered Protons…..kinda.

Dalton’s Assumptions-1808

• All matter is made of small particles called atoms.

• Atoms of the same element are identical in size, mass, and other properties.

• Atoms cannot be subdivided, created, or destroyed.

• Atoms of different elements can combine to form compounds.

• In a chemical reaction, atoms are combined, separated, or rearranged.

• 3 + 2 +2

Check for understanding-History of the atom1. Which Philosopher was responsible for the term “atomos”?

2. Which “scientist” revived Democritus's ideas regarding matter?

3. Which scientist used the cathode ray tube to isolate the electron in 1897?

4. Which Philosopher replaced the correct theory of atoms and made his own using the earthly elements?

5. Give an example from the atomic history that shows how scientists build on each other’s knowledge.

6. How have scientists used indirect observation to learn about atoms?

7. How have scientists taken advantage of accidental or unexpected experimental results to create new knowledge?

8. How did the “Gold Foil’ Experiment lead to the discovery of a Nucleus at the center of an atom?

9. Who is truly credited with the discovery of the proton?

10.Why did it take so long for the neutron to be discovered?

11.What made Chadwick pursue research of the neutron?

Silent Bellwork• Grab a card from the table and pick an

element from the periodic table (3-14).Fill out your card with that elements info.

• Grab a sheet from the table and cut off the edges so that it will fit in you comp book. Cut in between the words on the right to make flaps.

Anatomy of the Atom: Using the Periodic Table

• Atomic Number-gives the number of protons. – (whole number above each element)– Protons are Positive (always smiling)

• The # of Protons is the “soul” or “brain” of the atom– If you change this amount then you change

which element the atom is.• Protons are in the nucleus-center of the atom

+

Anatomy of the Atom/Periodic Table

• Electrons: Small negative particles that surround the nucleus of the atom

• Elements on the Table are neutral– On the periodic table atoms have the same # of

electrons as it does protons• protons and electrons cancel each other out

+ =

+1 + -1 = 0

_+

Or

Anatomy of the Atom/Periodic Table

• Each atom has a mass that is determined by # of protons and neutrons size Charge

• Protons mass: 1.673 x 10-27kg• Neutrons mass: 1.675 x 10-27 kg• Electrons mass: 9.109 x 10-31 kg . • Amu- Atomic mass unit• Protons are 1.007276 amu• Neutrons are 1.008665 amu

+

_

Anatomy of the Atom/Periodic Table

• Average atomic mass (Atomic Mass, Atomic

Weight)-weighted average of the atomic masses of the different isotopes of an element.– Listed underneath each element on the table

• Mass Number-The number of protons plus neutrons.This is NOT on the periodic Table. But it can be calculated.

Identify the anatomy of these Neutral Atoms

Element Symbol

Element Name

Atomic Number

Electrons

Average amount of Neutrons

Mass Number of most

common isotope

Average Atomic Mass

16

12

11

34

30.9738

48

Kr

75

1.

2.

3.

4.

5.

6.

7.

8.

Bell work

Element Symbol

Element Name

Atomic Number

Electrons Neutrons Mass Number

Average Atomic Mass

O

12

11

6.94

Anatomy of the Atom/Periodic Table Cont.

• An atom/element may NOT change protons but it CAN lose or gain electrons and neutrons.

• When an atom/element loses or gains electrons what do you think that will cause?

• Atoms that gain or lose electrons are called Ions. Ions have a + or – charge.

Identify the anatomy of these Atoms w/ a charge (Ions)

Element Symbol w/charge

Element Name

Protons Electrons Neutrons Average Atomic Mass

He+1

Strontium 36

5 4 6

Mg+3

35

Sulfur 18

83.80amu

37 35

Al+3

Isotopes• When an atom/element loses or gains neutrons what do

you think that will cause?• Make two columns on your paper to show a comparison

between Lemonas and Isotopes.– http://mmschemistryclass.weebly.com/chapter-3-and-

4-arrangement-of-electrons-in-atoms.html• What is an isotope?• What is mass number?• What are 2 ways an isotope is represented?

Isotopes• Isotopes: Atoms of the same element that

have different amounts of Neutrons. – This means some “weigh” more than others.– Most elements have more than one isotope.

• Mass #: Protons + Neutrons of an isotope– Has to be a whole numbers.

Isotopes cont

• How are Isotopes represented? – In 2 ways:

C-12 C-13 C-14

12C 13C 14C

Hyphen Notation

Nuclear Symbol

6 6 6

Isotopes

Calculating Average Atomic Mass

Mass # vs Average Atomic Mass•http://mmschemistryclass.weebly.com/chapter-3-and-4-arrangement-of-electrons-in-atoms.html

• Average Atomic Mass: The weighted average of all the isotopes for an element

• Formula: (%of isotope x atomic mass) + (%of isotope x atomic mass)

+ (%of isotope x atomic mass) …….etc.

1. Naturally occurring europium (Eu) consists of two isotopes with a mass number of 151 and 153. Europium-151 has an abundance of 47.81% (atomic mass of 150.9197 amu) and Europium-153 has an abundance of 52.19% (atomic mass of 152.9212. What is the atomic mass of europium?

2. Strontium consists of four isotopes Sr-84 with atomic masses of 84.012amu (abundance 0.50%), Sr-86 with 86.003amu (abundance of 9.9%), Sr-87 with 87.09amu (abundance of 7.0%), and Sr-88 with 88.012amu (abundance of 82.6%). Calculate the atomic mass of strontium.

Bellringer problem

• A Student believed that she had discovered a new element and named it mythium. Analysis found that it contained two isotopes. The composition of one of the isotopes was 19.9% with an atomic mass 10.013 and the other was 80.1% with an atomic mass of 11.009. What is the average atomic mass, and do you think mythium was a new element?

Isotopes/Avg Atomic Mass Quiz1-9 Give the number of protons, electrons, and neutrons for the following Isotopes:

Cu-65+2 54Xe Ba-1401.P= 4.P= 7.P=

2.E= 5.E= 8.E=

3.N= 6.N= 9.N=

134

10. How are two isotopes of a particular element the same and how are they different?

11. Copper has two isotopes: Cu-63 (abundance = 69.2%, mass = 62.930 amu) and Cu-65 (abundance = 30.8%, mass = 64.928 amu). Calculate the (average) atomic mass of copper.

12. What is the difference in Mass # and Average Atomic Mass?

Rewrite chart on your paper and fill in ALL the Question Marks with

correct info.

Isotope name atomic # mass # # of protons# of

neutrons# of

electrons Nuclear Symbol

Magnesium- ? ? ? 12 14 ?

Magnesium- ? ? ? 12 ? ?24Mg

? - ? 10 20 ? ? ?Neon-22 ? ? ? ? ?

12

Honors Isotope/Avg Atomic Mass Quiz

Symbol-Mass # % Atomic Mass of Isotope # protons #

electrons # neutrons Nuclear Symbol

Ne-20 90.48 19.992? ? ?

20Ne

Ne- ? 0.27 20.993? ? 11 ?

Ne- ? 9.25 21.991

? ? ? 22Ne

1. Draw the following chart on your own paper and replace all the question marks.

2. What is the Average atomic mass of the Neon Isotopes above? (Show Work)

10

10

3. How are two isotopes of a given element the same and how are they different?

4. Compare and Contrast Mass Number and Average Atomic Mass?

Mole• In chemistry it is not a cute animal that lives in the

ground.

• Chemistry definition of the Mole:– the amount of atoms in 12 grams of Carbon-12

6.02 x 1023 atoms of Carbon

12 Grams of Carbon

• 602 200 000 000 000 000 000 000 = 6.02 x 1023

Mole

• Avogadro’s number = 6.02 x 1023=1 Mole

Amedeo Avogadro: discovered the mole

• How many is a mole? If every person living on Earth (6 billion people) worked to count out one mole of oranges (or anything else), and if each person counted continually at a rate of one orange per second, it would take about 4 million years for all the oranges to be counted!

• If we had a mole of sand it would cover the earth 7 times over!

• If you had a mole of dollar bills, you could spend a million dollars every minute of your life and never spend it all!

• Answer 1-2 on the worksheet

Quiz

1. How was the mole determined?

2. What has more atoms, a mole of Hydrogen or a mole of Zinc?

3. How could molar mass be used as a conversion factor?

Molar Mass

• Molar Mass (Periodic Table)=Avg Atomic Mass• Unit for molar mass is g/1 mole

– Fill in Chart• 1 mole of carbon = 12.01 grams of carbon.

We can write this as a fraction:

• 1mole C or 12.01 g C

12.01 g C 1 mole C• Answer #3-7

Application

1. How many moles are in 50.0 grams of Au?

2. How many moles are in 25.0 grams of Ag?

3. How many moles are in 39.6 grams of F?

4. What is the mass of 4.5 moles of Carbon?

5. What is the mass of 1.625 moles of Si?

6. What is the mass of 5.81 moles of K?

• Answer #8-9

Moles and Grams Quiz

1. What is the mass of 4.30 mole of sodium?

2. What is the mass of 1.75 mole of Ca?

3. How many moles are there in 85.3 g of P?

4. Change 0.566 g of silver to moles.

Avogadro’s number as a conversion Factor

• To go from Atoms of C to Moles of Carbon.• I mole of C or 6.02 x 1023 atoms C

6.02 x 1023 atoms C 1 mole C

________________________________________

• I mole or 6.02 x 1023 atoms

6.02 x 1023 atoms 1 mole

• Fill in Chart

Application

1. How many atoms are in 4.2 moles of Cu?

2. How many atoms are in 6.5 moles of Zn?

3. How many moles are in 1.5 x 1012 atoms H?

4. How many moles are in 2.5 x 108 atoms Na?

• Answer #10-11

More Practice1. How Many atoms in 0.30 mole of sulfur?

 2. How many molecules are in 5.5 moles of silicon?

 4. Change 34 moles of lithium to atoms.

 5. You have 1.05 x 1023 atoms of Ca, how many moles of Ca do you have?

 6. You have 5.14 x 1023 atoms of P, how many moles do you have?

 7. Change 3.41particles of silver to moles of Silver.

Bell Ringer

1. How many moles are contained in

4.5 x 1012 atoms of carbon?

2. How many atoms are found in 6.25 moles of copper?

Mole Island• You can not go directly from atoms to

grams and vice versa.– To go from atoms to grams, first convert to

moles, then grams.– To go from grams to atoms, first convert

grams to mole, then moles to atoms.

Application

1. What is the mass of 4.3 x 1018 atoms of C?

2. What is the mass of 2.5 X 1012 atoms of Br?

3. How many atoms are contained in 265.0 grams of Ni?

4. How many atoms are contained in 25.5 grams of Fe?

5. What amount of moles are found in 6.71X1063 atoms of goop?

Gas at STP (Standard Temperature and Pressure)

• Avogadro’s Law: 1 mole of any gas at STP will occupy 22.4 L of space

• STP is 273 K (0° Celsius)  and 1atm of pressure.

• This can be used as a conversion factor

22.4L gas Or 1 mole gas

1 mole gas 22.4 L gas

Practice1. Suppose you have a balloon inflated to 2.00L at STP.How

many moles of gas are there?- .0893 mol2. What volume is occupied by 5.00 moles of any gas at STP?- 112 L 3. What volume will 0.75 moles of carbon CO2 occupy at STP

conditions? -16.8L4. What volume is occupied by 12.5 moles of nitrogen gas at

STP?-280L5. What volume is occupied by 100.0 grams of chlorine gas (Cl2)

at STP?-31.58L6. How many liters will 48.6 grams of CO2 occupy at 1 atm and

273K?-24.7 L7. What is the mass in grams of 17.0 liters of methane gas (CH4)

at STP?-12.2g

Isotope Practice

1.Write the hyphen notation for the element that contains 18 protons and 22 neutrons.

2. Write the hyphen notation for the element that has a mass number of 76 and an atomic number of 33.

3. Write the hyphen notation for the element that has 9 electrons and 10 neutrons.

Gram/Atom Quiz1. What is the mass of 4.5 x 1012 atoms of

Au?

2. How many atoms are in a 500.0 g piece of carbon?

3. How many pieces of sushi are in 5.2 moles of sushi?

Photoelectric Effect(Early 1900’s)

• Photoelectric effect-Heated metal absorbs energy and causes electrons to get excited.

• Photon of energy-Particle of light that is carrying enough energy to excite an electron– It takes a quantum of energy to excite an electron

PhotonQuantum of energy

- Woohoo!!

Fact Find Carousel • Goal: Everyone should have a complete chart by the

end of the time allotted.

• 5 min: In your pairs read over the 5 scientist info sheets. Underline info that you feel is important.– 5 min: Go online and look up a model of what each scientist

thought the atom looked like.• 1 min/scientist: In your groups go around to each

Scientist and write one important piece of info about that scientist’s discovery. Pictures are very helpful as well. (10-12 min total)

• 1 min/scientist: Work with your partner to complete the questions on each sheet-use info from wall as needed.

Fact Find Groups

• 25 min: Together as a group read and answer the questions from your scientist.– Go online and look up a model of your scientist’s

discovery• 20 min: Separate from your expert groups into

mixed groups and teach your peers.

• Goal: Everyone should have a complete chart by the end of the time allotted today and be able to identify the history of the development of the atomic model.