Chapter 1 Phlogiston theory materials that burned contained a substance called phlogiston and burning releases phlogiston The residue that remained was calx Law of conservation of mass the total mass of a reaction remains constant Mass is neither created nor destroyed during a chemical reaction Element pure substance that cannot be broken down by chemical reactions to a simpler substance Compound pure substance that contains more than one element Law of definite proportions elements of a compound are present in definite proportions by mass Law of multiple proportions when two different compounds are formed of the same two elements the masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers Dalton s atomic theory 1 elements are made of atoms 2 in rxns no atoms disappear or change 3 compounds form when atoms of different elements combine Atoms combine with one another to form molecules which are the smallest units of a substance that have the chemical properties of the substance Law of combining volumes volumes of reacting gases are in simple whole number ratios Avogadro s law equal volumes of gases at the same temp and pressure contain equal numbers of molecules Diatomic elements H N O F Cl Br I Modern atomic masses are based on C 12 If the masses of two pure substances are in the same ratio as their atomic masses then the substances contain the same number of atoms molecules Avogadro s number mole mol 6 022e23 number of atoms molecules present in a sample of an element compound with the mass of its atomic weight Molar mass mol g of a substance Mass of an individual atom molecule is expressed in atomic mass units amu Limiting reactant the reactant whose amount is consumed first limiting the amount of product The energy of a substance KE PE KE energy of motion KE mv2 PE energy due to position E final energy initial energy Positive E energy of the object increases Negative E energy of the object decreases All processes in nature seek the position of lowest energy Nature favors negative E Electromagnetic force is the force of attraction between two charged particles when they are close enough to each other Electromagnetic force can either be attractive or repulsive When the two particles have the same sign they are repulsive When the two particles have different signs the force is attractive At large separations charge particles do not interact JJ Thomson and the cathode ray determined that the cathode ray was made of charged particles the particles had a negative charge and the mass of electrons were much smaller than the mass of the whole atoms Millikan was the first to accurately determine the charge of an electron with the use of an oil drum Rutherford shot alpha particles at gold foil and determined that most of the volume of an atom is empty space and that the nucleus of an atom has a positive charge and is very small Electrons then must orbit the nucleus Atomic number is the number of protons in the nucleus Mass number protons neutrons 39 Cu means 39 is the mass number Isotopes are different forms of the same element that have the same atomic numbers but different neutrons so different masses Charge on a particle number of protons number of electrons Electrons are added or removed to produce ions Positive ions are cations Negative ions are anions Groups families on the periodic table are very similar Periods rows change gradually as you go across Periodic law arranged in the order of their atomic numbers the elements exhibit periodicity in their chemical and physical properties Chapter 2 Light is electromagnetic radiation White light is the sum of all of the colors that comprise visible light Speed of light frequency x wavelength Blackbody radiation is the emission of electromagnetic waves from a warm body Light is a stream of tiny photons Energy of each photon h x frequency Electrons are kept in their orbit by the Coulombic attraction of the nucleus A photon must be absorbed if the energy of the electron increases A photon must be released if the energy of the electron decreases Visible light comes from transitions of electrons The wavelength of each wave 2 x their length n Areas of zero wavelength in a wave are called nodes n 3 has 2 nodes Electrons and light can both behave as particles or wave equations The precise position and velocity of an electron cannot be known so we speak of their location in The principle quantum number n is 1 2 3 4 and designates the level in which the electron is found and the primary indicator of its energy Electrons with n 1 are closest to the nucleus and have the lowest most negative energy The angular momentum quantum number l designates the sublevel 0 l n l 0 sublevel s l 1 sublevel p l 2 sublevel d l 3 sublevel f Together n and l determine sublevel such as 2s 4p 3d The magnetic quantum number ml l m l This number dictates how many orbitals there are in probability a sublevel The spin quantum number ms can only be or It represents the spin of the electron about its own axis in a clockwise or counterclockwise direction because a magnetic field is produced by a charge moving in a circular path Pauli Exclusion Principle states that no electrons in the same atom can have all the same four quantum numbers Hund s rule states that the electrons in a sublevel that is less than half filled must occupy different orbitals within the sublevel and have the same spin The energy of an orbital is n l Chromium is Ar 4s1 3d5 Copper is Ar 4s1 3d10 Chapter 3 Valence electrons are in the outermost s level and in any partially filled sublevels Valence electrons do not feel the full positive charge of the nucleus because they are shielded from the nuclear charge by intervening electrons mainly the core electrons The nuclear charge that is actually experienced by the valence electrons is called the effective nuclear charge Zeff The nuclear charge experienced by the outermost electrons increases from left to right in a period Therefore it is higher for nonmetals than metals The highest Zeff is in the top right corner Screening is the reason that the energy of an electron in an atom depends upon n and l quantum Each nodal plane in an orbital reduces the electron density at the nucleus so as the l quantum number increases the shielding ability decreases Shielding ability is s p d f Greater Zeff lowers the energy of the electrons So orbital energies increase with l quantum numbers Increased l decreased Zeff increased