test 3: chapter 2

• what are atoms?

  small particles that make up matter which can not be broken down by chemical or physical means
• what information does a chemical formula tell you about an element or compound?

  • chemical formulas give the type of atom and how many of each atom there is

  what is an example of a chemical formula?

  • H2O (water) = two hydrogen atoms bonded to 1 oxygen atom
• what is a chemical reaction?

  a process which changes the chemical composition of a substance
• what is a chemical equation?

  a symbolic representation of what is happening in a chemical reaction

  • reaction --> products
• [chemical equation into a particle level statement]

  example:

  • Pb + S = PbS

  what is the particle level statement for this chemical equation?

  • one atom of lead and one atom of sulfur produces one molecule of lead sulfide
• [particle level statement into a chemical equation]

  example:

  • two molecules of hydrogen peroxide form two molecules of water and one molecule of oxygen.

  what is the chemical equation for this particle level statement?

  • 2 H2O2 --> 2H2O + O2
• what does the law of conservation of mass by lavoisier state?

  • mass is neither created nor destroyed ; matter only changes form
  • mass of the substance before reaction = mass of the substance after

  example:

  • mercuric oxide (HgO) --> mercury (Hg) + oxygen (O2)
  • 100.00 g 93.75 g + 6.25 g

  = 100.00 g (mass before = mass after)

  
  

  therefore, supports law of conservation of mass
• what does the law of definite proportions state developed by proust state?

  • a compound always contains elements in definite ratios and no others --> fixed combination

  almost like having the right amount of ingredients

  
  

  example: 1 frame + 2 wheels = 1 bike

  how many bicycles can be made from 100 wheels and 1 frame?

  1 bike and extra wheels
• what does the law of multiple properties by dalton state?

  • elements that combine in more than one ratio producing other substances

  example one: carbon and oxygen combine to form compound

  process level: carbon and oxygen form carbon dioxide or carbon monoxide

  
  

  12.01 g of C + 16.00 f of O2 --> 28.01 g of CO
• state the major principles of the atomic theory of matter developed by dalton

  1. all matter is made up of indivisible particles called atoms - can not be divided physically or chemically (exception: nuclear processes)
  2. all atoms of one element are the same; atoms of different element are different (exception: isotopes of the same element)
  3. compounds are formed when elements combine in fixed proportions - explains law of definite proportion and law of multiple proportions
  4. the rearrangement of atoms occurs in a chemical reaction
• how do we apply the atomic theory of matter to specific chemical situations?

  by analyzing how atoms interact and combine in different chemical reactions
• how do we use the atomic theory of matter to explain the three major laws of matter?

  we use atomic theory to explain how atoms combine and rearrange to follow these laws
• a mole is used as a way of counting numbers of atoms, molecules, or ions
• how do you determine the atomic mass of an element, and molar mass of an element?

  • to find atomic mass, look at periodic table. molar mass is the sum of atomic masses (multiply the number of atoms by atomic weight)

  example:

  • hydrogen atomic mass = 1.01 amu

  a)atomic mass = 1.01 amu

  b)molar mass = 1.01 g

  c)1 mole H 6.022x10^23 atoms

  d)molecular weight/mass of hydrogen molecule (h2)?

  • H: 2x1.01amu = 2.02 amu --> molecular weight (mass)
  • 2.02 g = molar mass (mole of H2)
• water H2O

  what is the molecular weight of water?

  • H = 1.01 amu
  • O = 15.99 amu

  2(1.01 amu) + 15.99 amu = 2.02 amu + 15.99 amu = 18.01 amu
• process level: the chemical reaction read as u would see the chemical change

  particle level: the reaction read as what is happening with the particles

  symbolic level: the chemical equation which symbolically represents the chemical reaction