Chapter 2 Outline Atomic Theory o John Dalton o The Law of Definite Proportions o The Law of Multiple Proportions o The Law of the Conservation of Mass Atomic Structure o Electrons o Millikan s Oil Drop Experiment o Thompson s Plum Pudding Model o Protons o Rutherford s Gold Foil Experiment o Nucleus o James Chadwick o Neutrons Atomic Number Atomic Mass and Isotopes o Atomic Symbols o Atomic Number Z o Atomic Mass A o Isotopes Calculating Protons Neutrons and Electrons Calculating Isotopic Mass from Percent Abundance Calculating Percent Abundance from Isotopic Mass Representative Transition Metals Lanthanides Actinides The Organization of the Periodic Table o Groups vs Periods o Metals Alkali Metals Alkaline Earth Metals Transition Metals o Nonmetals o Metalloids o Halogens o Noble Gases Molecules and Ions o Molecules Diatomic Molecules Polyatomic Molecules o Ions Cations vs Anions Ionic Compounds Monatomic Ions Polyatomic Ions Chemical Formulas o Empirical Formulas Percent Composition o Molecular Formulas o Allotropes Chemical Nomenclature o Ionic Compounds Monatomic Ions Polyatomic Ions Transition Metals o Polyatomic Ions per ates hypo ites ates ites o Oxoacids o Covalent Molecules Prefixes o Basic Organic Compounds Alkanes Alkenes Alkynes Chapter 2 Notes Atomic Theory o Several Scientists have contributed to the development of the model of the atom o John Dalton had a major impact on the model of the atom He described them as solid spherical structures that were indivisible and indestructible o A consequence of Dalton s study resulted in three major laws The Law of Definite Proportions states that molecules of the same substance will have the same ratio and arrangement of atoms An example is that all water molecules will have two hydrogen atoms and one oxygen atom The Law of Multiple Proportions states that if two molecules can combine to form more than one substance the masses of one element that combine with a definite mass of the second can be expressed in ratios of small whole numbers The Law of the Conservation of Mass states that matter cannot be created or destroyed but can only change form This is to say that atoms that are present at the beginning of a process must be present at the end but can be rearranged Atomic Structure neutrons o Atoms are made up of three major subatomic particles electrons protons and Electrons are located on the outside of an atom and carry a representative charge of 1 and a representative mass of 0 Millikan used charged oil drops to calculate the charge of an individual electron by suspending them in an electrostatic field Thompson pointed out that atoms were electrically neutral so they must contain the same number of positives as negatives This lead to his Plum Pudding Model The substance of an atom is positive and negative electrons are scattered throughout Protons are located inside the nucleus and carry a representative charge of 1 and a representative mass of 1 Rutherford shot positively charged alpha particles at gold foil and noticed that most of the particles went straight through He also noticed that some of them were repelled and sent backwards at sharp angles This indicated that most of an atom is empty space and that protons exist in a tightly packed center named the nucleus James Chadwick bombarded beryllium with alpha particles and a new subatomic particle was released It was found that the particle was about the same size as a proton but had no charge For this reason it was called a neutron Neutrons are located inside the nucleus have a representative mass of 1 and a representative charge of 0 Atomic Number Atomic Mass and Isotopes o Atomic symbols are unique to each element When writing atomic symbols capital letters are SIGNIFICANT Charge o Atomic Number is represented by Z and is equal to the number of protons o Atomic Mass is represented by A and is equal to the sum of the protons and neutrons o Isotopes are atoms that have the same number of protons but a different number of neutrons and thus a different atomic mass o Charge is equal to the number of protons minus the number of electrons To calculate average atomic mass given percent abundance and mass of known isotopes A Abundance1 mass1 Abundance2 mass2 Abundance is expressed as a decimal Mass is in amu To calculate abundance given average atomic mass and the mass of known isotopes A x mass1 1 x mass2 x is the abundance of the first isotope in decimal form 1 x represents the abundance of the second isotope in decimal form o It s 1 x because 1 represents 100 of all known isotopes The Organization of the Periodic Table o The periodic table is organized in order of increasing atomic number number of protons Do not confuse this with atomic mass as some spots break that trend o Groups also known as families are vertical on the periodic table o Periods are horizontal rows on the periodic table o Metals make up about 70 of the periodic table They are good conductors of heat and electricity and most are solids at room temperature There are a few types of metals Alkali metals are group 1 the first group from the left Alkaline earth metals are group A the second group from the left Transition metals are located in the center of the periodic table The representative transition metals are numbers 21 30 39 48 72 80 and 104 112 The inner transition metals include The lanthanides numbers 57 71 The actinides numbers 89 103 o Nonmetals are located towards the right of the periodic table They are poor conductors of heat and electricity and most of them are gases at room temperature o The metalloids are the elements that have properties of both metals and nonmetals They form the zigzag step on the periodic table and include boron silicon germanium arsenic antimony tellurium and polonium o The halogens are group 17 the second from the right o The noble gases are group 18 the farthest group to the right Molecules and Ions o Molecules usually describe the combination of two or more nonmetals Diatomic molecules are molecules that contain two of themselves The diatomic molecules to know are hydrogen nitrogen oxygen fluorine chlorine bromine and iodine All of these substances exist as diatomic molecules in their natural state Polyatomic molecules are molecules that contain two or more different nonmetal elements o Ions are charged particles electrons protons the chloride ion Cl Cations are positively charged ions They have more protons than Anions are negatively charged ions They have more
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