DALTON’S ATOMIC THEORY (1808) 1. All elements are composed of atoms, which are indivisible and indestructible particles. 2. All atoms of the same element are exactly alike; in particular, they all have the same mass and properties. 3. Atoms of different elements are different; in particular, they have different masses and different properties. 4. Compounds are formed by the joining of atoms of two or more elements in small whole ratios. 5. Atoms retain their identity in chemical reactions.

MODERN ATOMIC THEORY 1. Atoms are NOT indivisible. They are made up of smaller particles—protons, neutrons, and electrons. 2. Atoms can be changed from one element to another, but NOT by chemical reactions. 3. Atoms of the same element are NOT all exactly alike. They are alike in those characteristics that determine the chemical properties of an element. But atoms of the same element can and do have different masses. PROTON NEUTRONELECTRON Charge: Mass (amu) 1 1 1/1837 NOTE: amu = atomic mass unit, a unit for expressing masses of atoms and subatomic particles.

CHEMICAL LAWS LAW OF CONSERVATION OF MASS A 7.12 g sample of magnesium is heated with 1.80 g of bromine. All the bromine is used up, and 2.07 g of magnesium bromide is produced. What mass of magnesium remains unreacted? Law of Definite Proportions A g sample of magnesium, when combined with oxygen, yields g of magnesium oxide. What masses of magnesium and oxygen must be combined to make exactly 2.00 g of magnesium oxide? Law of Multiple Proportions The following data were obtained for compounds of iodine and fluorine: CompoundMass of Iodine (g)Mass of Fluorine (g) A B C D If the formula for compound A is IF, what are the formulas for compounds B, C, and D?

Workshop on CHEMICAL LAWS LAW OF CONSERVATION OF MASS When g of marble chips, calcium carbonate, are treated with50.0 mL of hydrochloric acid (d = g/mL), the marble chips dissolve resulting in a solution and releasing the gas carbon dioxide. The final solution weighed 60.4 g. How many liters of carbon dioxide was released if the density of the gas is g/L? Law of Definite Proportions Galena, a mineral of lead and sulfur contained g of lead in a g sample. (a) calculate the mass of sulfur in the sample. (b) calculate the mass fraction of lead. © calculate the mass percent of lead. (d) How much reactant is needed to produce g of product, galena? Combined Laws Aluminum metal reacts with bromine, a red-brown liquid with a noxious odor. The reaction is vigorous and produces aluminum bromide, a white crystalline material. A sample of g of aluminum yields g of aluminum bromide. How many grams of bromine will react with g of aluminum?

may come in one of three forms:

ISOTOPIC NOTATION ISOTOPIC NOTATION isotopes are atoms with the same number of protons but different number of neutrons A Z X A = mass number (the total number of protons + neutrons) Z = atomic number (the total number of protons) X = element symbol ***The number of protons in an atom identifies that atom *** For neutral atoms, the number of protons equals the number of electrons

Workshop on subatomic particles Define the following: (1) ISOTOPES: (2) IONS: (3) ANIONS vs. CATIONS: (4) AMU: (5) Complete the following table: ION# p# n# eION# p# n# e Li + F - Ca 2+ O 2- P -3 Sn 4+

Workshop on isotopes Complete the following table: SymbolAtomic # Charge Mass number # of proton # of neutrons # of electrons H 0 3 Li 7 2 Al 0 27 _____ _____

Atomic Mass The atomic mass of an element represents the average mass of all the isotopes found in nature. No element exists with only one possible isotope. Hydrogen has the smallest number of isotopes: 1 H protium, 2 H deuterium, 3 H tritium. Its atomic mass is amu (atomic mass units). The atomic mass is calculated by adding the % of 1 H mass found in nature to the % of 2 H mass found in nature plus the % of 3 H mass. % 1 H + % 2 H + % 3 H = average mass (atomic mass) Generally the formula used is: % X + % Y + % Z… = atomic mass. An instrument called the mass spectrometer is generally used to determine the percentages and individual masses of each isotope.

1. An element consists of 90.51% of an isotope with a mass of amu, 0.27% of an isotope with a mass of amu, and 9.22% of an isotope with a mass of amu. Calculate the average atomic mass and identify the element. 2. The element silver has two naturally occurring isotopes: 109 Ag and 107 Ag with a mass of amu. Silver consists of 51.82% 107 Ag and has an average atomic mass of amu. Calculate the mass of 109 Ag. 3. The average atomic weight of lithium is amu. The two naturally occurring isotopes of lithium have the following masses: 6 Li, amu; 7 Li, amu. Calculate the percent abundance of 6 Li and 7 Li in naturally occurring lithium. ATOMIC MASS

Important Scientists and their Impact on Chemistry – you should be able to write short answer responses highlighting the important contributions of each scientist listed below (to be looked up on your own!): 1. J.J. Thomson 2. Henri Becquerel 3. Ernest Rutherford A.Gold Foil Experiment B.Types of radiation: 1.Alpha (  ) radiation 2.Beta (  ) radiation 3.Gamma (  ) radiation

THE PERIODIC TABLE WORKSHOP: Contrast the organization by Mendeleev vs. Moseley Consider the generic schematic of the periodic table shown below. Identify the chemical family or group of elements represented by each letter. A: ________________________ E: ________________________ B: ________________________F: ________________________ C: ________________________G: _______________________ D: ________________________H: _______________________

THE PERIODIC TABLE Metals Located on the left side of the periodic table Tends to lose electrons to form cations Has low ionization energies & electronegativity values Forms compounds with nonmetals but not other metals Good conduction of heat and electricity Lustrous & malleable solids excepts Hg which is a liquid Ductile Nonmetals Located on the right side of the periodic table Tends to gain electrons to form anions Has high ionization energies & electronegativity values Forms compounds with both metals and nonmetals Poor conduction of heat and electricity Non-lustrous & brittle or gaseous Non-ductile

WORKSHOP on the Periodic Table Briefly describe each of the components of the periodic table: (1) Metals: Alkali Metals: Alkaline Earth Metals: Transition Metals: Lanthanides: Actinides: (2) Nonmetals: Halogens: Noble Gases: (3) Metalloids: