Period+G+Chapter+4+&+5

=__ CHAPTERS 4 & 5: __=

__GROUP 1__: Pages 101- 107

 * Co-editor: Lauren Altmeyer **

Early Models of the Atom (by Lauren Bedard) Matter: -Made of particles (atoms) that can’t be seen with unaided eye Atom: -The smallest particle of an element that retains its identity in a chemical reaction -Concept intrigued scholars who were able to predict the structure without the technology that allowed them to actually view individual atoms

[picture: [] by Lauren Bedard] Democritus’s Atomic Theory by Lauren Bedard Democritus: -Greek philosopher; among first to suggest existence of atoms -Ideas agreed with scientific theory, but didn’t explain chemical behavior and lacked experimental support(didn’t use scientific method)
 * believed that atoms were invisible and indestructible*

Photo by Lauren Bedard

Daltons Atomic Theory (p.102) by Julia McNamara DALTON'S ATOMIC THEORY a result of a chemical reaction. John Dalton (Julia McNamara) Sizing Up the Atom (p. 103) by Lindsey Bedrosian ~Dalton's concept of the atom -A penny made of pure copper ground into the smallest particle that can no longer be divided is an atom. -Atoms are time, but numerous in number. The radii of most atoms is 5x10 to the -11th power to 2x10 to the -10th power -Despite size, atoms can still be seen and observed with instruments such as scanning, tunneling microscopes -Individual Atoms can be moved and arranged in patterns -Holds promise for future creation of atomic-sized electric devices -Nanoscale Techonolgy could become essential to future applications in medicine, communications, solar energy, and space exploration Photo by Lindsey Bedrosian
 * The modern process of of discovery regarding atoms began with John Dalton.
 * By using experimental methods, Dalton transformed Democritus's ideas on atoms into a scientific theory.
 * The result of this was:
 * 1) All elements are composed of tiny indivisabkle particles called atoms
 * 2) Atoms of the same element are identical. The atoms of any one element are different from those of any other element
 * 3) Atoms of differents elements can physically mix together or can chemically combine in simple whole-number ratios to form compounds.
 * 4) Chemical reactions occur when atoms are seperated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as

Subatomic Particles (p. 104) by Mark Cuddy -Going against Dalton's theory, **atoms are divisible.** -3 Kinds: Electrons, Protons, Neutrons
 * -Subatomic Particles-** the smaller particles of an atom that have specific ways of acting for the atom.

Electrons by Mark Cuddy -Discovered by JJ Thomson 1 -Passed electric currents through gases at low pressure. 2 -The gases were sealed in glass tubes with metal disks called electrodes at both ends of them. 3 -These electrodes were connected to an electrical source. 4 -One of the electrodes, called the anode, became positively charged, while the other, the cathode, became negatively charged. Page 105 by Emily Taylor and Kelsey Sullivan
 * -Electrons-** negatively charged subatomic particles.
 * -Thomson's experiment**:
 * 5** -Result was a glowing beam, or Cathode Ray, that traveled from the cathode to the anode.

-A cathode ray is deflected by a magnet and electrically charger metal plated. -A postively charged plate attracts the cathode ray and the negatively charged plate deflects that cathode ray. -Thomson hypothesized that a cathode ray is a stream of tiny negatively charged particles moving at a high speed. These particles became known as electrons. -To test this, Thomson set up an experiment to measure the ratio of the charge of an electron to its mass, and found that the ratio was constant. -The charge-to-mass ratio of electrons did not depend on the kind of gas in the cathode ray tube or the type of metal used for the electrodes. -Thomson concluded that electrons must be parts of the atoms of all elements. photo by: Emily Taylor


 * US Physicist Robert A. Millikan performed experiments to determine the quantity of charge carried by an electron
 * Millikan's values for an electrons charge and mass from 1916 are similar to those accepted today.
 * An electron carries one unit of negative charge
 * Its mass is 1/1840 the mass of a hydrogen atom



photo by: Kelsey Sullivan

Protons and Neutrons (p.106) by Lauren Altmeyer
-Atoms are electrically neutral--they have no net electric charge -Electric charges are carried by particles of matter -Electric charges always exist in whole number multiples of a single based unit - An electrically neutral particle is formed when a given number of negatively charged particles combines with an equal number of positively charged particles -Eugene Goldstein discovered the proton -James Chadwick discovered the neutron

The Atomic Nucleus by Lauren Altmeyer -J.J. Thompson discovered the electron -Thompson came up with the 'plum-pudding model'--similar to raisins stuck in dough



Rutherfords Experiment (p. 107) by David O'Brien - tested the atomic structure with his experiment - a beam of alpha particles were shot at a thin sheet of gold foil - previous theory stated particles would pass through foil with no deflection - instead the alpha particles went through with some deflection - some particles split off into large angles - some bounced back

photo by David O'Brien

Theories by David O'Brien - Atom is mostly empty space - Nucleus caused the deflection of the alpha particles that bounced back - Nucleus = tiny central core of an atom and is made up of protons and neutrins

Co-editor: Colleen Fitzgerald
==== The Development of Atomic Models (p.127) by Meghan Faber ====
 * At first the atom was known to consist of protons and neutrons in the nucleus and were surrounded by electrons
 * Rutherford had the idea the in an atom the electrons move around the nucleus
 * This idea only explained few and simple properties of atoms.

 The Bohr Model (p. 128-129) by Meghan Faber
http://www.biology.lsu.edu/introbio/Links1/oxygen.gif image by Meghan Faber (it wouldn't show...)
 * Niels Bohr (a student of Rutherford) thought the atom model needed to be improved.
 * Bohr's new model said that an elecron is found only in specific circular paths around the nucleus
 * Each electron in the model had a fixed energy (energy levels- lowest rung, lowest energy level)
 * **Quantum:** the amount of energy needed to move an electron from one energy level to the next
 * The energy levels in an atom are not equally spaced (higher energy-less space between)
 * The higher the energy level, the less energy it takes to move to a higher energy level
 * Does not explain the energies absorbed and emitted (lost) by atoms with more than one electron

Atomic Number by Alexandra Fischbach
- Atoms = protons, neutrons and electrons. - Nucleus = protons & neutrons - - Electrons surround the nucleus - Elements are different because they contain different numbers of protons - Atomic number = # of protons in the nucleus of an atom - - Identifies an element - - # of protons = # of electrons - - Protons are - - - Electrons are + - - Must balance each other out - - Atoms are electrically neutral - Hydrogen's atomic number is 1 - - Hydrogen atoms have 1 proton

Mass Number by Alexandra Fischbach
- Mass of an atom is concentrated in it's nucleus & depends on the # of P&N - Mass number = the total # of P&N in an atom - - Helium atom has 2 protons, 2 neutrons = mass number is 4 - Atomic # & mass # = atom's composition - Atomic #

--# of protons
--# of electrons

- Number of neutrons = mass number – atomic number - The atomic number is the subscript. The mass number is the superscript

Photo by: Alexandra Fischbach

Quantam Mechanical Model By: Colleen Fitzgerald

-Developed by Austrian physicist Erwin Schrodinger -Developed by devising and solving a new mathematical equation that described the behavior of the electron in the hydrogen model -Resticts the energy of electrons to certain values -Determines the allowed energies an electron can have and how likely it is to find the electron in various locations -The chances of finding an electron is descibed by probablity -The probablility of finding an electron within a volume of space is represented by a cloud -The cloud is less dense when the probablity of finding the electron is low, and more dense when the probablility is high

Atomic Orbitals By:Colleen Fitzgerald

-Region of space where there is a high probability of finding an electron -Energy levels are labled by principal quantam numbers and values (1,2,3,4 etc...) -Each energy level corresponds to an orbital of a different shape, which descibes where the electron is likely to be found -Atomic orbitals are either s(sphereical shaped), p(dumbell shaped), or d (clover shaped) - Number and kinds of atomic orbitals depend on energy sublevel -The maximum number of electrons that can occupy a principal energy level is 2 x the principal quantam number squared

photo by:Colleen Fitzgerald

Atomic Mass (pgs 114-116) By Marybeth Nametz
-this instrument could find the actual masses of individual atoms which provided useful information -however the values were TOO SMALL and were hard and impractical to work with
 * mass of atoms are all extremely small; even the largest atom
 * since 1920's it has been possible to determine the masses of atoms by using a //mass spectrometer//

-the chosen isotope is //carbon-12// -it was assigned a mass of exactly //12 atomic mass units// -a mass of a single proton or neutron is about one-twelfth of 12 amu, or about 1 amu
 * in order to compare relative masses of atom, it was more usful to use a reference isotope as a standard
 * __//Atomic Mass Unit (amu)://__ one twelfth of the mass o
 * f a carbon-12 atom
 * a carbon-12 atom has six protons and six neutrons in its nucleus and its mass is set as 12 amu


 * in nature, most elements occur as a mixture of two or more isotopes
 * each isotope of an element has a fixed mass and a natural percent abundance
 * //__Atomic Mass:__// (of an element) is a weighted average mass which reflects both the mass and the relaive abundance of the isotopes as they occur in nature

-the resulting sum is the weighted average mass of the atoms of the element as they occur in nature Atomic mass of carbon = (12.00 amu X 0.9889) + (13.003 amu X 0.0111) = 12.011 amu  photo by: Marybeth Nametz []
 * To determine atomic mass based on relative abundance three values must be known:
 * 1) the number of stable isotopes of the element
 * 2) the mass of each isotope
 * 3) the natural percent abundance of each isotope
 * **To calculate the atomic mass of an element, multiply the mass of each isotpe by its natural abundance, expressed as a decimal, and then add the products**
 * ====﻿Ex: (to calculate atomic mass of carbon)====


 * __GROUP 3__: Pages 133-146 **

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Electron Configurations (p.133-134) By <span style="font-size: 1.3em; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">: <span style="color: #000080; font-size: 1.3em; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">Anne O'Toole ===== >> >> >>> Photo by: Anne O'Toole ( [] ) >>> >>> >>> Photo by: Anne O'Toole ( http://mrdchemgwiki.wikispaces.com/Period+G+Chapter+4+%26+5 ) >>> >>> Pauli Exclusion Principle (p. 134) By: Erika Paiva >>> - An atomic orbital may describe at most 2 electrons. >>> - Either one or two electrons can occupy an s orbital or a p orbital. >>> - Two electrons can occupy the same orbital if the two electrons have opposite spins. >>> - Electron spins must be paired according to the Paulie Exclusion principle. >>> - Spin: is a quantum mechanical property of electrons >>> - Spin can be in a clockwise or counterclockwise direction >>> - Direction of an electron's spin is indicated by a vertical arrow. ( pointing up or down.) >>> uwsp.edu >>> Picture by: Erika Paiva >>> >>> Hund's Rule (p. 134-135) By: Erika Paiva >>> - Electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin as large as possible. >>> - EX: electrons would occupy three orbitals of equal energy, then the second electrons would occupy each orbital so that their spins are paired with the first electron in the orbital. >>> (This makes the number of electrons with the same spin as large as posssible.) >>> >>> >>> en.citizendium.org >>> Picture By: Erika Paiva >>> >>> =====<span style="color: #ff00ff; font-size: 120%; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">Exceptional Electron Configurations (p.136) <span style="color: #000080; font-size: 120%; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">By Grayce Rose ===== >>>>>>> >>>>>>> >>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> (copper is an example of an element that's >>>>>>>>> electron configuration does not follow the aufbau principle) (Model of aufbau principle) >>>>>>>>> picture by: Grayce Rose >>>>>>>>> Picture by: Grayce Rose >>>>>>>>> >>>>>>>>> >>>>>>>>> Light (p.138-139) by Kim Kogut >>>>>>>>> >>>>>>>>> >>>>>>>>> photo by Kim Kogut >>>>>>>>> >>>>>>>>> -Isaac Newton tried to prove that light was made of particles. However, it's made up of waves. >>>>>>>>> -Each wave cycle starts at zero, increases toward its height, passes through zero toward its lowest point, then returns to zero again. >>>>>>>>> -The frequency and wavelength of light are proportional to each other. >>>>>>>>> -Light is made up of **electromagnetic waves**. >>>>>>>>> -Sunlight has a continous range of wavelengths and frequencies. >>>>>>>>> -In a **spectrum**, each color blends into the next. >>>>>>>>> -Red light has the longest wavelength and the lowest frequency, while violet has the shortest wavelength and the highest frequency. >>>>>>>>> >>>>>>>>> Vocabulary: >>>>>>>>> -**Amplitude:** A wave's height from zero to the crest. >>>>>>>>> **-Wavelength:** The distance between the crests. >>>>>>>>> **-Frequency:** The number of wave cycles to pass a given point per unit of time. >>>>>>>>> **-Electromagnetic radiation:** The rays that light consists of; this includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. >>>>>>>>> **-Spectrum:** The seperation of different frequencies that results in color (s). A prime example is rainbow. >>>>>>>>> >>>>>>>>> <span style="color: #ff00ff; font-size: 120%; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Page 141 <span style="color: #000080; font-size: 120%; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"> by Erin Garrity >>>>>>>>> >>>>>>>>> >>>>>>>>> ~__Atomic Spectra__ >>>>>>>>> >>>>>>>>> >>>>>>>>> ~__An explanation of an Atomic Spectrum__ >>>>>>>>> >>>>>>>>> >>>>>>>>> Page 144 by Brendan Lynch >>>>>>>>>  ﻿ · Quanta are units of energy; light quanta are called photons >>>>>>>>> · Because light moves in wave like patterns people began to experiment to see if matter did the same >>>>>>>>> · It was confirmed with experimentation >>>>>>>>> · Today people use wavelike beams for viewing microscopic items >>>>>>>>> · Matter can only visibly move in a wavelike motion if its mass is very small >>>>>>>>> · Classical mechanics must be used for observation of our bodies >>>>>>>>> · The Heisenberg uncertainty principlestates it is impossible to know the exact velocity and positionof a particle at the same time >>>>>>>>> · This theory lead to many other advances in the field of Chemistry >>>>>>>>> Picture by Brendan Lynch
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">The ways in which electrons are arranged in various orbitals around the nuclei of atoms are called **electon configurations**
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">__Aufbau Principle__
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">According to this principle, electrons occupy the orbitals of lowest energy first
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">The orbitals for any sublevel of a principle enegy level are always of equal energy
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">The range of energy levels within a prinicpal energy level can overlap the energy levels of another principal level
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">some elements are an exception to the aufbau principal (ex: copper)
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">you cannot use the aufbau model to assign electron configurations after atomic number 23 (vanadium)
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">electron configurations sometimes differ from those that are assigned to them with the aufbau principal
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">half filled sublevels aren't as stable as filled sublevels
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">they are however, more stable than other configurations
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">these exceptions to the aufbau principle are a result of subtle electron-electron interactions in orbitals with very similar energies
 * <span style="margin: 0.5em 0px 0px; padding-bottom: 0px; padding-left: 3em; padding-right: 0px; padding-top: 0px;">it is worth knowing the exceptions to the aufbau principle, but it is more important to understand the general rules for determining electron configurations
 * When energy is absorbed electrons move to areas of higher energy
 * When energy is lost electrons move to areas of lower energy
 * Each line in an emission spectrum relates to one frequency
 * Each emission spectrum is unique
 * The Bohr model predicted specific values of frequencies
 * Ground state is when an atom has the minimal number of electrons in the outside ring (1)
 * The amount of light given off by an electron is directly related to its change in energy
 * Later a quantum mechanical modelbased on the descriptionof motion replaced the Bohr model