# Principles of Chemistry I

Flashcard maker : Keisha White
 Macroscopic
 properties and behavior we can see (ex. color, flammibility, volume, mass)
 submicroscopic
 properties and behavior we can not see (ex. atoms, molecules, chemical bonds)
 Extensive Properties
 dependent on amount of sample (mass, volume)
 Intensive Properties
 independent of amount of sample; some can be used to identify substances  (temp, density, gas pressure, melting point)
 SI Units
 length = meter (m) mass = kilogram (kg) time = second (s) amt of substance = mole (mol) temp = kelvin (K) electic current = ampere (A) luminous intensity = candela (cd)
 Celsius to Kelvin
 C = K – 273.15
 Celsius to Fahrenheit
 F = 1.8C + 32
 Fahrenheit to Celsius
 C = .56 (F-32)
 Accuracy
 How closely a measurement agrees with a true value
 Precision
 How closely individual measurements agree with each other
 Systematic Error
 a constant error that affects all measurements the same
 Random Error
 a variable error that affects each measurement differently
 Significant Figures in Addition and Subtraction
 The answer has the same number of decimal places as the measurement with the fewest decimal places 89.5 + 45.25 + .123 = 134.9
 Significant Figures with Multiplication and Division
 The answer contains the same amount of significant figures as the measurement with the fewest significant figures 12.25 + .256 + 23 = 72
 Isotopes
 atoms with the same number of protons, but different numbers of neutrons.
 Atomic number (Z)
 the number of protons or electrons(defines atom)
 Mass number (A)
 the number of protons + neutrons
 Atomic mass
 mass of a single atom in atomic mass units (amu)
 Molecular mass
 mass of a single molecule in atomic mass units (amu)   the sum of the atomic masses of each atom in a molecule
 Formula Unit mass
 the mass of all of the atoms in a formula unit in amu
 Empirical formula
 shows the simplest integer ratio of atoms of each element in a compound.
 Molecular formula
 shows the number of atoms of each element in a molecule.
 Structural formula
 shows the connectivity of the atoms in a molecule.
 Matter
 the physical material of the universe (has mass and occupies space)
 Atom
 the building block of matter
 What determines the properties of matter?
 Composition- which atoms? Structure- how are atoms connected?
 What do we do in Chemistry?
 Attempt to understand the properties and behavior of matter by studying the properties and behavior of atoms and molecules
 Gas
 no fixed volume or shape confomrs to volume and shape of container particles far apart and moving rapidly
 Liquid
 distinct volume but no shape assumes shape of portion of container it occupies particles packe close together and moving rapidly (can be poured)
 Solid
 distinct shape and volume particles held tightly together with little movement
 Pure Substance
 Matter with distinct properties and constant composition Can be either -element -compound
 Mixture
 Combination of 2+ pure substance Relative amts of components can vary Each component retains its own properties
 Homogeneous and Heterogeneous Mixtures
 homo- composition of same materials (solution) hetero- composition of different materials
 Physical Properties
 Observe without changing the identity or composition of a substance (color, density, melting point, boiling point)
 Chemical Properties
 Describe the way a substance may change or react to form other substances (flammability)
 Physical Change
 1. Substance changes physical appearance but not composition 2. Changes of state are physical changes (melting ice)
 Chemical Change
 1. Substance is transformed into a different substance 2. Called a chemical reaction (hydrogen burns in air to form water)
 Democritus
 Found matter is particulate or made of particles rather than continuous mass.
 Dalton’s Atomic Theory (Postulates)
 1. All matter consists of tiny indivisible atoms. 2. Atoms of an element are identical, but different from those of other elements. 3. Atoms of one element cannot be converted into those of another element. 4. Compounds result from chemical combinations of different elements; atom ratios are integers.
 Law of Conservation of Mass
 Total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.
 Law of Constant Composition
 Whether in Ankeny or Anchorage, water contains 11.19% hydrogen and 88.81% oxygen by mass.
 Law of Multiple Proportions
 If 2 elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers.
 Are Dalton’s Postulates always true?
 1. Nuclear fission does divide atoms. 2. Nuclear transmutations do change atoms of one element into those of another. 3. Atoms of an element are not identical. 4. Nonstoichiometric compounds sometimes appear to have non-integer atom formulas/ratios.
 J.J. Thomson
 English physicist won nobel prize in 1906. Worked with Cathode rays. Measured the charge-to-mass ration of the electron (1.76×10^8 C/g) Credited for the discovery of electrons
 Cathode rays
 Independent of the electrode material (different metals create the same results) Are streams of negatively charged particles (electrons)
 Robert Millikan
 American pysicist "Oil-drop" experiment Caused oil drops to become charged and observed their behavior in an electric field.  This led to the charge on the electron= 1.602×10^-19 C Given charge to mass ration he computed electron mass to be 9.1×10^-28 g
 Plum-Pudding Model of the Atom
 1. Evenly distribute mass and positive chare (cookie) 2. Small embedded negative particles (chocolate chips)  Disproved by Rutherford’s Gold-Foil Experiment in 1910 ;
 Ernest Rutherford
 New Zealand physicist; Father of nuclear physics Discovered the nature of radioactivity Explained the phenomenon of radioactivity (spontaneous emission from uranium compounds) ;Gold-Foil; Experiment Discovered protons in 1919
 Gold Foil Experiment
 Studied angles at which alpha particles were scattered after passing through thin gold foil. This experiment disproved the plum-pudding model of the atom Alpha Rays- particles; electrons Beta rays- particles; protons Gamma rays- non-particles; nuetrons
 Rutherford’s Nuclear Atom
 a small, very dense, positive nucleus surrounded by negative electrons atom diameters:~100-500 pm nuclei diameters:~10^-2 pm ratio= 10,000 : 1
 Discovered neutrons in 1932
 Periodic Table
 Rows= periods Columns = groups
 Alkali metals (1A)
 Li,Na,K,Rb,Cs,Fr
 Alkaline earth metals (2A)
 Bc,Mg,Ca,Sr,Ba,Ra
 Chalcogens (6A)
 O,S,Se,Te,Po
 Halogens (7A)
 F,Cl,Br,I,At