Models of the Atom and Electron Arrangements Page | 9

Unit 2: Models of the Atom and Electron Arrangements

Name:______

Date Due / Assignments / Page Number: Problem Numbers
Assignment 1: Atomic Symbols / 129: 42
Assignment 2: Isotopes & Isotopic Calculations / 129: 43, 44, 53
131: 1, 3, 5, 6-9
Assignment 3: Radiation Calculations / 375: 11, 12
379: 13, 14
Assignment 4: Valence Electrons / 386: 26
Assignment 5: Quantum Electron Configurations / 386-387: 33, 45, 52

A.  Distinguishing Between Different Types of Atoms

Defining Terms

Atomic Number-

Mass Number -

Isotopes

Atomic Mass

Particle / Location / Relative Charge / Relative Mass
(amu) / Actual Mass

Ions -

Cation -

Anion-

In general

•  metals lose electrons and therefore form cations

•  nonmetals gain electrons and therefore form anions

State the number of protons, neutrons, and electrons in each of these ions.

39 K+ 16O -2 41Ca +2

19 8 20

#p+ ______

#no ______

#e- ______

Write the nuclear symbol form for the following atoms or ions:

A. 8 p+, 8 n, 8 e- ______

B.17p+, 20n, 17e- ______

C. 47p+, 60 n, 46 e- ______

Determining Proton, Neutron and Electron Numbers from Element Symbols

Fill in the blanks using your knowledge of atoms, isotopes and ions.

Symbol / Protons / Neutrons / Electrons / Atomic Number / Mass Number / Net Charge
117Sn
18 / 20 / 0
127I-1
24Mg
5 / 6 / 0
56Fe3+
18O-2
3H
22 / 20 / 26


Isotopic Calculations

Given that the atomic mass is the average mass of the isotopes of an element, weighted by the proportions of the isotope present, calculate the following quantities.

1.  What is the atomic weight of carbon, given the following isotopes and their natural abundances?

C-12: 98.89%

C-13: 1.11%

2.  What is the atomic weight of magnesium, given the following isotopes and their natural abundances?

Mg-24: 78.70%

Mg-25: 10.13%

Mg-26: 11.17%

3.  Silver consists of two isotopes 107Ag and 109Ag. Its average atomic mass is 107.87. Calculate the percentage of each isotope in naturally occurring silver. (Assume that the masses are 107.00 and 109.00 respectively.)

4.  Calculate the atomic mass of naturally occurring neon, which is a mixture of 90.48% neon-20 (atomic mass = 19.99 amu), 0.27% neon-21 (atomic mass = 20.99 amu), and 9.25% neon-22 (atomic mass = 21.99 amu.)

5.  35Cl and 37Cl are the only naturally occurring chorine isotopes. What percentage distribution accounts for the atomic weight of 35.453?

B.  Properties of Light and Radiation

The Electromagnetic Spectrum & Calculations with Light Energy

A Labeled Wave:

Calculations Associated with Energy and Light:

E = hυ h (Planck’s constant) = 6.63 × 10-34 J·s c = λυ c = 3.0 × 108 m/s

Practice with Radiation Calculations

Answer the following questions using the equations on the previous page. The following conversions may be useful.

1/s, s-1 or Hertz (Hz), 1nm (nanometer) = 1 x 10-9 meter

1.  The wavelength of the green light from a traffic signal is 5.22 x 10-7 meters. What is the frequency?

2. The blue color of the sky results from the scattering of sunlight by air molecules. The blue light has a frequency of about 7.5 x 1014 Hz. What is the wavelength of this radiation?

3. FM radio station KDKB broadcasts at 93.3 MHz (1 megaHertz = 106 Hz). What is the length of waves broadcast by this station?

4. Radio waves in the AM region of the spectrum have frequencies in the range of 550 to 1400 kilocycles per second (kHz). What frequency on your tuner would you find a station that broadcasts a signal with a wavelength of 229 meters?

5. Microwaves have frequencies in the range 109 to 1012 /s (cycles per second.) What is the wavelength of radiation in your microwave oven whose frequency is 2.40 x 1010 /s.?

6. Yellow colors in fireworks are due to the 589 nm (5.89 x 10-7m) radiation of sodium ions. How much energy is given off by one photon of sodium?

7.  What is the relationship between frequency and wavelength of electromagnetic radiation?

8.  What do we mean when we say that energy of light is quantized?

Ground Electron States for Atoms

The ground electron state is the condition of the atom where all of the electrons occupy the lowest available orbitals.

The valence shell is the outermost shell that holds electrons. The valence electron number is the number of electrons in the outermost shell. Each shell can hold 2n2 electrons.

Drawing Ground Electron States

Complete the following diagrams by placing the correct number of electrons in each shell.

Hydrogen Boron

Neon Chlorine

Silicon Argon


Shorthand Electron State Configurations

1.  Give the symbols and names of the elements that correspond to the number of electrons in consecutive shells as shown below.

a.  2-8-5

b.  2-8-18-8

c.  2-8-18-8-2

d.  2-3

e.  2-8-6

2.  How many electrons are in the highest occupied energy level of these atoms?

a.  Selenium

b.  Nitrogen

c.  Calcium

d.  Neon

3.  Give short hand electron configurations for atoms of these elements.

a.  Si

b.  Fe

c.  Na

d.  Al

Excited States for Atoms

The Excited Electron State: An atom where one of the electrons has been promoted into a higher energy orbital. This configuration is not very stable.

Show a possible energy transition for each of the following atoms using circles to represent electrons.

→

Sodium Sodium*

→

Phosphorus Phosphorus*

→

Neon Neon*

Give a possible excited state configuration for the following elements.

Aluminum Helium Scandium

Valence Electrons-

Octet Rule-

Fill in the charts below.

Electron Configuration / Element / Valence Electrons / Possible Excited State
1 / 2-7
2 / 2-8-4
3 / 2-3
4 / 2-5
5 / 2-8-1
6 / 2-6
7 / 2-2

Ions

Ion: At atom in which an electron(s) has been lost from or gained by the valence shell of the atom.

Write the electron configuration for the following atoms and their corresponding ions.

Atom / Electron Configuration / Most likely Ion / Electron Configuration
1 / Li
2 / Be
3 / O
4 / F
5 / Na
6 / Mg
7 / Cl


The Interaction of Radiation and Electrons

When an electron jumps from the ground state to the excited state, energy is absorbed. When an electron falls from the excited state to the ground state, energy is released, in the form of light or heat.

Pictoral Representation:

1.  Absorption:

2.  Emission

Wave Mechanical Model of the Atom

Principal Quantum Number-

Sublevel / Number of Orbitals / Number of Electrons


*There can only be two electrons per orbital

Three rules for filling orbitals

Aufbau principle-

Pauli Exclusion Principle-

Hund’s Rule-

Diagonal Rule-

Aufbau Diagrams

Complete the orbital diagrams for: Oxygen, Boron, Phosphorus, Vanadium, Iron, and Arsenic.

Oxygen Boron

Phosphorus Vanadium

Iron Arsenic

Electron Configurations Wave-Mechanical Model

Write wave mechanical electron configurations for the following neutral atoms.

1. As

2. Ne

3. Si

4. Ni

5. Ti

6. O

7. He

Name the elements that match the following electron configurations.

1.  1s2 2s2 2p6 3s2 3p2

2.  1s2 2s2 2p6 3s2 3p6 4s1

3.  1s2 2s2 2p5

4.  1s2 2s2 2p6 3s2 3p6 4s2 3d7

5.  1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

  1. Write electron configurations for Be, Mg, Ca and Sr. What is the similarity in the configurations of the outermost electrons in these elements?

Noble Gas Configurations

Write noble gas configurations for the following neutral atoms.

Na:

V:

Se:

Sr:

Sb: