# Semester 1 Final

Flashcard maker : Daniel Jimmerson
 Chemistry
 The study of matter
 Substance
 a material with a definite chemical composition
 Scientific Law
 a statement that explains what something does in science
 Density/Volume
 Volume and density have derived units. Density which is a ratio of mass to volume, can be used to identify an unknown sample of matter. D=mass/volume
 Kelvin
 To get Kelvin it equals the Celsius temperature plus 273
 Derived/Base Units
 a set of seven base units from which all other units of measurement are formed, by products of the powers of base units: Gram, Liter, Meter, Second, Kelvin
 Scientific Notation
 To add or subtract numbers in scientific notation, must have same exponent2. To multiply or divide in scientific notation, multiply or divide the coefficients and then add or subtract exponents respectively.
 Dimensional Analysis
 Dimensional analysis uses conversion factors to solve problemsNew Unit/Given Unit
 Accuracy
 An accurate measurement is close to the accepted value. A set of precise measurements shows little variation
 Error
 Error is the difference between the measured value and the accepted value. Error = experimental value – accepted valuePercent error = l error l / accepted value * 100
 Precision
 The number of significant figures reflects the precision of reported data
 Milli-
 1/1000 or 0.001
 Centi-
 1/100 or 0.01
 Kilo-
 1000
 Sig Figs
 1. If decimal is present, start counting from the left at the first non-zero digit.If not present, start from the right side at the first non-zero digit.2. +/-: Find the answer, then round to the least significant place of any measurement in the problem3. x/: Answer has the same number of sig figs as the least sig. # in the problem.
 Isotopes
 Atoms of the same element (same atomic #) but with a different number of neutrons(different mass #
 Isotopic Notation
 Symbolic:atomic mass SymbolAtomic Number Written Form:Element–atomic mass
 Bar Graphs
 Shows how a factor varies with time, location, or temperature
 Line graph
 continuous, and can interlope between data
 Physical Property
 can be observed without altering a substance’s composition
 Chemical Property
 a substance’s ability to combine with or change into one or more new substances
 Intensive Property
 Properties that do not depend on the amount of the matter present: Color, Odor, Luster, Malleability, Ductility, Conductivity, Hardness, Melting/Freezing Point, Boiling Point, Density
 Extensive Property
 Properties that do depend on the amount of matter present: Mass, Weight, Volume, Length
 States of Matter
 Gas, Liquid, solid (sometimes vapor)
 Law of Conservation of Mass
 states that mass is neither created nor destroyed during a chemical reaction.
 Solutions
 Homogeneous(same) mixtures
 Mixtures
 -A physical blend of two or more pure substances in any proportion-Can be separated by physical means.-Common separation techniques: filtration, distillation, crystallization, sublimation, chromatography
 Law of definite Proportions
 states that a compound is always composed of the same elements in the same proportions-percent by mass= (mass of the element/mass of the compound)x100
 Law of Multiple Proportions
 states that a chemical compound always contains exactly the same proportion of elements by mass
 Dalton’s Atomic Theory
 Elements are made of extremely small particles called atoms.Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.Atoms cannot be subdivided, created, or destroyed.Atoms of different elements combine in simple whole-number ratios to form chemical compounds.In chemical reactions, atoms are combined, separated, or rearranged
 Atom
 the smallest particle of an element that maintains the properties of that element-consists mostly of empty space surrounding the nucleus
 Isotopes
 atoms of the same elements with different numbers of neutrons
 Chemical Reactions vs. Nuclear Reactions
 Chemical reactions involve changes in the electrons surrounding an atom. Nuclear reactions involve changes in the nucleus of an atom and conserve atomic # and mass #
 Alpha (charge of 2+)-4 not very penetrating He low speeds 2Beta (charge of 1-)– 0 e -1Gamma (no charge or mass)
 1/2 Life
 amount left=original amount(1/2)^n # of half lives- n=t/Tt=time passedT= 1/2 life timen # of 1/2 lives
 emit radiation to attain more stable configurations
 Transmutation
 conversion of an atom to an atom of another element by radioactive decay processes- the bombardment of of nuclei with particles (induced transmutation)
 Nuclear Fusion
 the process by which two or more atomic nuclei join together, or “fuse”, to form a single heavier nucleus-target + projectile=product nucleus + ejected particles
 Nuclear Fission
 refers to either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei), often producing free neutrons and photons (in the form of gamma rays), and releasing a very large amount of energy
 Frequency
 the # of waves that pass a given point per second-Units: cycle/sec or hertz (Hz or sec^-1)=v
 Speed of light
 c=3.00 x 10^8 m/sc=hv
 Light Spectrum
 left= low energy, low frequency, longer wavelengthright= high energy, high frequency, shorter wavelength-Further the electron drops to the ground state, the higher the energy
 Photons
 Packets of radiant energy-energy of a photon is proportional to its frequency E=hr
 Planck’s constant
 6.6262 x 10^-34 Jxs=h– Planck= energy emitted or absorbed by an object can only be done in specific, distinct amounts (like a ladder)
 Bohr
 Energy depends on its proximity to nucleus (merry-go-round)close=lowfar= high
 Quantum Mechanical Model
 The atom is found inside a blurry “electron cloud”- an area where there is a high probablility of finding an electron-assumes that electrons have wave properties
 s sublevel
 # of orbitals: 1Max electrons:2Starts at energy level:1
 p sublevel
 # of orbitals: 3Max electrons:6Starts at energy level:2
 d sublevel
 # of orbitals:5Max electrons:10Starts at energy level:3
 f sublevel
 # of orbitals:7Max electrons:14Starts at energy level:4
 Heisenberg uncertainty principle
 a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known
 Quantum Number
 the energy level of the electron
 Aufbau Principle
 an atom is “built up” by progressively adding electrons. As they are added, they assume their most stable conditions (electron orbitals) with respect to the nucleus and those electrons already there.
 Pauli exclusion principle
 An orbital can hold 0, 1, or 2 electrons only, and if there are two electrons in the orbital, they must have opposite (paired) spins. Therefore, no two electrons in the same atom can have the same set of four Quantum Numbers.
 Hund’s rule
 When filling sublevels other than s, electrons are placed in individual orbitals before they are paired up.
 Periodic law
 when the elements are arranged by increasing atomic number, there is a periodic repetition of their chemical and physical properties.
 Medeleev vs Modern Table
 Mendeleevordered by increasing atomic mass, periodicity based on formulas of compounds, other: subgroups, “mixed bag,” graveyards and junkpiles Modern: ordered by increasing atomic mass, periodicity based on valence electron config, other: actually split (A-s and p/B-d), Metals/metalloids/nonmetals, actinides and lanthanides (f-block)
 Alkali Metal
 Group 1
 Alkaline Earth metals
 Group 2
 Halogens
 Group 7
 Representative Elements
 d elements
 Transition element
 s and p blocks
 decrease from left to right, increase as you move down
 Ionization energy
 the energy needed to remove an electron-generally increases from left to right, decreases as you move down
 Octet rule
 states that atoms gain, lose, or share electrons to acquire a full set of eight valence electrons
 Electronegativity
 attraction an atom has for a shared pair of electrons-generally increases from left to right, decreases as you move down-difference determinds bond type-bigger distance=more ionic
 Cation
 positive, Metal Ions
 Anion
 negative, nonmetal ions
 Ionic Compound
 contain ionic bonds formed by the attraction of oppositely charged ions.-Ions in an ionic compound are arranged in a repeating pattern known as a crystal lattice.-Ionic compounds properties are related to ionic bond strength.-are electrolytes
 electrolytes
 conduct an electric current in the liquid phase and in aqueous solution.
 Metallic Bond
 forms when metal cations attract freely moving, delocalized valence electrons.
 Metal Alloys
 formed when a metal is mixed with one or more other elements
 Covalent bonds
 form when atoms share one or more pairs of electrons
 Resonance
 occurs when more than one valid Lewis structure exists for the same molecule
 Coordinate Covalent Bond/Dipole
 the two electrons derive from the same atom
 VSEPR model theory
 states that electron pairs repel each other and determine both shape of and bond angles in a molecule
 Hybridization
 explains the observed shapes of molecules by the presence of equivalent hybrid orbitals.