Attacking the TEKS: Atomic Structure

Jane SmithCentennial High School Frisco, TXsmithja@friscoisd.org

TEKS(6) Science concepts. The student knows and understands the historical development of atomic theory. The

student is expected to: (A) understand the experimental design and conclusions used in the development of modern

atomic theory, including Dalton's Postulates, Thomson's discovery of electron properties, Rutherford's nuclear atom, and Bohr's nuclear atom;

(B) understand the electromagnetic spectrum and the mathematical relationships between energy,

frequency, and wavelength of light; (C) calculate the wavelength, frequency, and energy of light using Planck's constant and the speed

of light; (D) use isotopic composition to calculate average atomic mass of an element; and (E) express the arrangement of electrons in atoms through electron configurations and Lewis

valence electron dot structures. (2) (B) know that scientific hypotheses are tentative and testable statements that must be capable of being

supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories;

(2) (C) know that scientific theories are based on natural and physical phenomena and are capable of being

tested by multiple independent researchers. Unlike hypotheses, scientific theories are well established and highly-reliable explanations, but may be subject to change as new areas of science and new technologies are developed;

College Readiness StandardsB. Atomic structure 1. Summarize the development of atomic theory. Understand that models of the

atom are used to help understand the properties of elements and compounds. a. Describe the discoveries of Dalton (atomic theory), Thomson (the electron),

Rutherford (the nucleus), and Bohr (planetary model of the atom); understand how each discovery contributed to modern atomic theory.

b. Identify the masses, charges, and locations of the major components of the atom (protons, neutrons, and electrons); describe Rutherford’s “gold foil” experiment that led to the discovery of the atomic nucleus; and describe Millikan’s “oil drop” experiment that led to determining the charge on an electron.

c. Describe basic wave properties (calculate wavelength, frequency, or energy of light) and understand that electrons can be described by the physics of waves.

d. Explain the importance of quantized electron energy and its relationship to atomic emission spectra.

e. Understand the electron configuration in atoms (Aufbau principle, the Pauli

exclusion principle, Hund’s rule) and their connection with the periodic table

The Basics

Time Frame: 6 – 90 minute periods or 9 – 50 minute periods on the atom ; 6 – 90 minute periods or 9 – 50 minute periods on electrons

Electrons/Periodic Table on one test?

Engage

Think – pair – share with previous knowledge of the atom

Use that to discuss the properties and location of the subatomic particles.Representing the composition of an atom with symbols and names.Isotope vs. ion

History of the Atom

Alchemy – qualitativeBalance – quantitativeDalton – 1st theory Cathode ray tube –

subatomic particles

Radioactivity – gold foil experiment

Bright line spectra – Bohr model

Nuclide Labblack beans = protons popcorn = electrons white beans = neutrons

bag # protons electrons neutrons atomic # mass # symbol name

1

2

3

How are the atoms of isotopes of an element similar? How are they different? Provide at least three examples of bags that illustrate the characteristics of isotopes. List all of the information that the imaginary symbol indicates.

Ex289117

16 bags with several isotope pairs

Mass Number vs Atomic Mass

Students use atomic number, mass number and atomic mass indiscriminately

Quick intro activity to atomic mass:– 2 bags 9 p+ 8 no

– 3 bags 9 p+ 11 no

– 21 bags 9 p+ 10 no

18.96 amu

Working with conversion factors

6.02 X 1023 atoms Ag = 1 mole Ag = 107.87 g AgIf I asked for a 0.15 mole silver ring from my husband, what would be its mass in grams?

equivalence statements to conversion factors3 examples6 problems

Agmol

AggAgmol

1

87.10715.0

Mole Lab TasksTask A1 Determine the mass of the

zinc strip. Calculate:Moles of zinc in the stripAtoms of zinc in the stripHow many moles of zinc would

be found in 15 strips?

Task B1 Determine the mass of 15 cm3

carbon (activated charcoal). Calculate:Moles of carbon in the 15 cm3

Atoms of carbon in the 15 cm3

How many moles of carbon would be found in 3.0 m3?

3 different tasks involving conversions between grams, moles, and atoms

A Penny’s Worth of ZincCalculations: All calculations are to be shown with complete work, units and boxed answers. Round your

answers to a total of 3 sig figs. Skip lines between calculations.

What is the mass of zinc in your penny?

What is the percentage, by mass, of zinc in your penny?

What is the percentage, by mass, of copper in your penny?

Calculate the number of moles of zinc in your penny.

Calculate the number of moles of copper in your penny.

Calculate the number of atoms of zinc in your penny.

Calculate the number of atoms of copper in your penny.

Analysis:Describe what evidence you have that this was a chemical reaction. Post-1984 pennies are actually 97.5% zinc. Calculate your percent error and give sources of error that might

account for the difference. % error = experimental – actual X 100 actual

Use conversion factors and the current metal prices (posted on the board) to determine the value of 1000 pre-

1984 pennies and the value of 1000 post-1984 pennies. You may assume that all pennies have the same initial mass as yours. (1 lb = 454 g)

2 day lab

Atom ReviewState two principles of Dalton’s atomic theory that have been revised, as new

information has become available. What information caused the revisions to be made?

A cathode ray produced in a gas-filled tube moves away from a negative field, such as

one produced by a magnet. When a paddle wheel is installed inside the tube, the wheel moves down the tube in the same direction as the cathode ray. What properties of electrons do these phenomena illustrate?

What changes did Rutherford make to Thomson’s atomic model in order to explain

the results of his gold foil experiment? Be sure you relate experimental observations to changes in the model.

Suppose you could shoot a proton beam, an electron beam and a neutron beam

between two electrically charged plates. Assuming the velocities are the same, draw a diagram to show the paths of each type of subatomic particle.

The element boron has an atomic mass of 10.81 amu according to the periodic table.

However, no single atom of boron has a mass of exactly 10.81 amu. How can you explain this difference?

Atom Review Write the symbol, , for each of the isotopes described below: • Z = 8, number of neutrons = 9• the isotope of chlorine in which A = 37• number of electrons = 26, number of neutrons = 31• iodine-131

The following elements have only two naturally occurring isotopes. Use the average atomic mass on the periodic table to determine which isotope is more abundant and justify your choice.

• iridium-191 and iridium-193• silver-107 and silver-109

XAZ

A MOLEVELOUS MAGICAL SQUARE!

A D G

B E H

C F I

Answer Bank - answers may be used once or not at all!

1. 2.44 moles 5. 354 grams2.0.20 moles 6. 55.85 amu

A How many zinc atoms would be in 2.44 moles of zinc?

B 1.20 X 1023 helium atoms is equivalent to how many moles?

G 8.76 X 1024 atoms of magnesium weighs how much, in grams?

Atom TestWhich principle of Dalton’s atomic theory did Thomson disprove?

A. Different atoms have different masses.B. All atoms of the same element have the same mass.C. Compounds always have the same percentage composition by mass.D. Atoms are indivisible.E. Atoms can be combined to make compounds.

Which of the following statements are true of uranium-238?I. Its chemical properties will be exactly like those of uranium-235.II. Its mass will be slightly different from that of an atom of uranium-235.III. It will contain a different number of protons than an atom of uranium-235.IV. It is more plentiful in nature than uranium-235.

 A. III, IVB. I, II, IIIC. I, II, IVD. II, III, IVE. all of these

Low Frequency High Frequency

Long

Wavelength

Short

Wavelength

Visible Light

Electromagnetic Spectrum

700 nm 600 nm 500 nm 400 nm

Radiowaves Microwaves Infrared Ultraviolet X rays Gamma rays

Low Energy High Energy

Wavelength and frequency are ________ related.

v = f

c =

Energy and frequency are ________ related.

E = h

Lab Experiences

Flame TestsUsing the results of your flame tests, list the element symbols in order of increasing energy they emit.________ In order of increasing wavelength -____________.Why do the chemicals have to be heated in the flame first before the colored light is emitted?

Continuous and bright line spectrabright line spectrum - ______________ tubeviolet red

Learning goals with electrons

• Write orbital notation

• Write electron configuration

• Write noble gas notation

• Identify location on periodic table

• Identify valence electrons

• Draw a Lewis dot symbol

Orbital NotationElement

Atomic Number 1s 2s 2p 3s 3p 3d 4s 4p

H 1                                    

He 2                                    

Li 3                                    

Be 4                                    

B 5                                    

6 examples complete for the 1 st 31 elements

Check out: Dr .John Gelder’s (@OSU) electron configuration (Aufbau) simulation

Electron ConfigurationElement

Atomic Number

Electrons in Energy Levels Electron Configuration

H 1

He 2

Li 3

Be 4

B 5

1st 31

elements -

revisit with

Cu and Cr

exceptions

Discuss energy level patternsCircle valence electrons on

configurationsDraw dot diagrams

Transfer patterns to periodic table

Electron Horse Race

Set #4For the following ground state electron configurations, indicate the part that is wrong and explain what is wrong.

(a) 1s22s22p103s2

(b) 1s22s22p62d3

(c) 1s22s22p63s23d74s2

(d) 1s22s22p43s23p5

(e)1s22s22p63s23p63d3

Set #6 Given the configuration

1s22s22p63s23p64s23d104p65s24d2

group #?

period #?

metal or nonmetal?

block of the periodic table?

# of valence electrons?

Questions 1- 5 refer to elements listed below. The elements may be used once, more than once or not at all.

A. manganeseB. magnesiumC. potassiumD. phosphorusE. argon

1. Is an alkali metal.2. Is a transition metal3. Is an alkaline earth metal4. Is a noble gas5. Is found in the d-block

Which one of the following electron configurations is incorrect?

A. Calcium [Ar]4s2

B. Copper [Ar]3d104s1

C. Manganese [Ar] 4d54s2

D. Tin [Kr] 4d105s25p2

Using principles of atomic structure, answer the following questions regarding the sulfur-34 atom.

a) Determine the number of protons and neutrons in a sulfur-34 atom.

b) Write the complete electron configuration for sulfur-34.

c) Write the orbital notation (label it!) for the valence electrons in a sulfur-34 atom.

d) Draw the Lewis dot diagram for sulfur.e) Is a sulfur-34 atom diamagnetic or paramagnetic?

Explain.