Chem 1075 Chapter 5 Models of the Atom Lecture Outline

Transcription

1 Chem 1075 Chapter 5 Models of the Atom Lecture Outline Slide 2 Dalton Model of the Atom John Dalton proposed that is made up of The particles are or can be broken down into by chemical processes. cannot be by or processes. Slide 3 Dalton s Theory A Summary of Dalton s Atomic Theory: 1) An element is composed of particles called atoms. 2) All atoms of an element are. 3) Atoms of elements combine to form. 4) Compounds contain atoms in. 5) Atoms can combine to form different compounds. Slide 4 Dalton s Atomic Theory The first 2 parts of Dalton s theory were later proven incorrect: INDIVISIBLE: Two particles were discovered. 1) charged, (relative charge of ) 2) charged, (relative charge of ) INDESTRUCTIBLE: Nuclear reactions were later discovered where of atoms occurred. Slide 5 Dalton s Atomic Theory IDENTICAL: were discovered, where atoms of the element had masses. Slide 6 Thomson s Model of the Atom

2 Slide 7 Mass of Subatomic Particles Mass of electron: Mass of proton: NOTE: The proton is times heavier than the electron. Slide 8 Types of Radiation Three types of radiation: 1) Alpha ( ) particles are composed of 2) Beta ( ) particles are composed of 3) Gamma ( ) rays are Slide 9 Rutherford s Gold Foil Experiment Rutherford fired α-particles at. If the plum pudding model was correct, they should pass through. Most alpha particles. Some alpha particles were. A few alpha particles were. Slide 10 Explanation of Scattering Most of the alpha particles through the because an atom is mostly. Some alpha particles were at small angles because the helium nucleus encountered a in the atom. Rutherford proposed that at the center of the atom is the which contains the atom s.

3 The alpha particles that bounced did so after striking the nucleus. Slide 11 Rutherford s Model of the Atom Rutherford proposed a new model of the atom: The charged are distributed around a charged (containing protons and neutrons). Slide 12 Subatomic Particles Revisited Based on the of the nucleus, Rutherford predicted that it must contain particles in addition to. were discovered about years later. A neutron has the same of a proton, but is. Mass is expressed in amu,, when small particles are concerned x amu = 1 g OR 1 amu = g Slide 13 Atomic Notation or Nuclear Symbol

4 Each element has a unique number of in the nucleus. This is the. The total number of in the nucleus of an atom is. We use to display the number of protons and neutrons in the nucleus of an atom: Slide 14 Using Atomic Notation or Nuclear Symbol An example: The element is. The atomic number is. The mass number is the atom of. The number is neutrons is:. Slide 15 Isotopes All atoms of the have the same number of. Most elements occur naturally with. Atoms of the that have a number of in the nucleus are called. Isotopes have the same but different numbers. Slide 16 Isotopes of Hydrogen protium deuterium tritium What is the same? What is different? Slide 17 Isotopes Continued We often refer to an isotope by stating the of the element followed by the number. Cobalt-60 is Carbon-14 is How many protons and neutrons does an atom of mercury-202 have?

5 Slide Practice: Complete the table Isotope Name Isotope Symbol Atomic No Mass No # p+ # n o # e- Neon I Slide 24 Simple & Weighted Averages A simple average assumes. A weighted average takes into account the fact that we do not have. A weighted average is calculated by multiplying (as a decimal number) by its and adding the numbers together. Slide 25 Average Atomic Mass Since not all isotopes of an atom are present in, we must use the. Copper has two isotopes: 63 Cu with a mass of amu and 69.09% abundance 65 Cu with a mass of amu and 30.91% abundance The average atomic mass of copper is: Slide 26 Practice Slide 27 Periodic Table We can use the periodic table to obtain the and of an element. The periodic table shows the,, and for each element. Slide 28 Wave Nature of Light Light travels through space as a similar to an. Wavelength is the light travels in. Frequency is the number of completed each. Light has a speed:.

6 Slide 29 Wavelength vs. Frequency Slide 30 Visible Spectrum Light usually refers to radiant energy that is visible to the human eye. The visible spectrum is the range of. Radiant energy that has a wavelength lower than 400 nm and greater than 700 nm. Slide 31 Radiant Energy Spectrum The complete radiant energy spectrum is an, or. Slide 32 The Wave/Particle Nature of Light In 1900, Max Planck proposed that radiant energy is not, but is emitted in. This is the. Radiant energy has both a nature and a nature. An individual unit of light energy is a. Slide 33 The Quantum Concept The concept states that is present in bundles. For example: A tennis ball that rolls down a loses potential energy.

7 A tennis ball that rolls down a loses potential energy in. The loss is. Slide 34 Bohr Model of the Atom Niels Bohr speculated that electrons orbit about the nucleus in. Electrons are found only in, and nowhere else. The are quantized. Orbits or Energy Levels are designated etc. Slide 35 Emission Line Spectra When an is passed across a gas in a sealed tube, a series of is seen. These lines are the. The emission line spectrum for shows three lines: 434 nm, 486 nm, and 656 nm. Slide 36 Evidence for Energy Levels The electric charge temporarily an electron to a. When the electron, a photon is given off. The wavelength of the corresponds to the released when the electron drops from. Slide 37 Atomic Fingerprints The of each element is. We can use the for the of elements, using their. See Fig A Continuous Spectrum versus Line Spectra

8 Slide Energy Levels and Sublevels Electrons occupy within each E level. Sublevel designations:,,, and The number of sublevels in each E level is the same as the n value of the E level. The first E level ( ) has sublevel: The second E level ( ) has sublevels: The third E level ( ) has sublevels: The fourth E level ( ) has sublevels: The fifth E level ( ) has sublevels: In reality, the highest sublevel to be filled with electrons is the. The sublevels beyond that remain unfilled. Slide 40 Quantum Mechanical Model An orbital is the where there is a high probability of finding an. In the quantum mechanical atom, orbitals are The higher the of an orbital, the its size. Slide 41 Shapes and Orientations of s-orbitals S-orbitals have a shape. There is orientation for s-orbitals. Slide 42 Shapes and Orientation of p-orbitals p-orbitals have a shape. There are orientations for p-orbitals. Slide 43 Shapes and Orientation of d- and f-orbitals d-orbitals have a shape. There are orientations for d-orbitals. f-orbitals have a shape. There are orientations for f-orbitals. Slide 44 Electron Occupancy in Sublevels

9 The number of electrons per is. The orbital holds a maximum of electrons ( ) The orbital holds a maximum of electrons ( ) The orbital holds a maximum of electrons ( ) The orbital holds a maximum of electrons ( ) Slide 45 Electrons per Energy Level Energy Level Energy Sublevel Max e - in Sublevel Max e - in Energy Level 1 1s 2 2s 2p 3 3s 3p 3d 4 4s 4p 4d 4f Slide Filling Diagram for Sublevels & Electron configurations Slide 48 Using the Periodic Table Slide 49 Electron configurations

10 The electron configuration of an atom is a shorthand method of The sublevel is written followed by a superscript with the number of electrons in the sublevel. If the 2p sublevel contains, it is written The electron sublevels are arranged according to. Slide He B O Na P Ar K Slide 52 Writing Electron Configurations Complete Writing Electron Configurations (More Practice) Shorthand