Chem I Exam 1

Chapter 1:

  • Law- is a measured relationship between two variables

  • hypothesis- is a scientific guess

  • Theory- is an explanation and explains why or how

  • Purpose- state the problem

  • Research- find out about the topic

  • Experiment- determine the experiment

  • Macroscopic- big picture (what I can see or hear)

  • Microscopic- at the level of atoms and molecules

  • Physical State of Matter- solid, liquid, gas, plasma

  • Plasma- a material made up of stars

  • Mixtures- can be separated physically

  • Compounds- can be separated chemically

  • Physical Change- same substance presents a different physical setting

  • Chemical- different substances present the same or different physical forms (ex rust)

  • Extrinsic Properties- depends on how much of the substance there is (mass, volume)

  • Intrinsic- depends only on what the substance is (ex. density, luster)

  • Density- d=m/v

SI units

  • Length- meter (m)
  • Mass- kilogram (kg)
  • Time- second (s)
  • Amount of substance - mole (mol)
  • Temperature- Kelvin (K)
  • Giga- 10^9
  • Mega- 10^6
  • Kilo- 10^3
  • Centi- 10^-2
  • Milli- 10^-3
  • Micro- 10 ^-6
  • Nano- 10^-9
  • Pico- 10^-12

Measurement Reading Scales

  • Accuracy- how close are you to the right answer
  • Precision- based on the scatter (or same results)
  • To calculate accuracy- take the average
  • To calculate precision- do the standard deviation

Dalton's Atomic Theory (1807-1808)

  • Element- composed of extremely small particles called "atom"
  • Compound- substances composed of two or more elements
  • Law of definite proportions- different samples of the same compound contain elements in the same proportions by mass
  • Law of multiple proportions- if elements combine to form more than one compound of masses of one element that combine with a fixed mass of the other, will always be a small whole number ratio

Three types of rays emitted by radioactive elements

  • A (alpha)- positively charged and are heavier than beta
  • Y (gamma)- does not have a charge
  • B (beta)- negatively charged
  • Plum pudding model of the Atom- 1904 first idea for what an atom looks like

Basic atomic structure

  • Electrons- negatively charged (-1.602 x 10^-19 C)
  • Protons- positively charged
  • Neutron- neutral charge
  • Atomic number- number of protons uniquely identifies the element
  • Mass number- number of protons plus neutrons
  • Neutral atom- the number of electrons equals the number of protons

Periodic Table

  • Period- rows

  • Groups- columns

  • Group 1 - alkali metals

  • Group 2- alkaline earth metals

  • Group 3-12- transition metals

  • Group 17- halogens

  • Group 18- Noble gases

  • AMU- atomic mass unit

Chemical Formulas

  • Methane- a major component of natural gas
  • Ethanol- grain alcohol
  • Alcohol- things with OH on it
  • Isotopes- the same number of protons but different neutrons
  • Isomers- different chemical structures but the same formula
  • Cis- next to
  • Trans- across
  • Ions- charged atom or molecule made up of one or more molecules
  • Recall- number of protons defines the identity of an element
  • Cation- positive ion
  • Anion-negative ion
  • Examples of cations-  iron, copper, zinc, silver, ammonium
  • Examples of anions- sulfide, nitrate, oxide, fluoride, chloride, bromide, iodine