chemistry exam

• human method to make discoveries about the natural world: science
• is the branch of science involved with the properties and behavior of matter, and the changes it undergoes during a reaction with other substances

  chemistry
• is the use of resources to solve a problem (such as knowledge, skills, processes, techniques, tools, and raw materials).

  technology
• applies organic chemistry, inorganic chemistry, biochemistry, analytical chemistry, and physical chemistry to reduce and prevent pollution. 

  Green chemistry
• 1. Prevent waste
  2. Design safer chemicals and products
  3. Design less hazardous chemical syntheses
  4. Use renewable raw materials
  5. Use catalysts, not stoichiometric reagents
  6. Avoid chemical derivatives
  7. Maximize atom economy
  8. Use safer solvents and reaction conditions
  9. Increase energy efficiency
  10. Design for degradation
  11. Analyze in real time to prevent pollution
  12. Minimize the potential for accidents

  12 guiding principles in the practice of green chemistry
• a tentative explanation that can be tested by further investigation

  hypothesis
• is a well-supported explanation of observations

  theory
• Refine explanations regarding the body of knowledge “how?” “Why?” Particulate realm


  Theory
• statement or set of statements that summarizes the body of knowledge. Tend to answer the question “what?” Macroscopic Realm

  Law
• is a method of investigation involving experimentation and observation to acquire new knowledge, solve problems, and answer questions. The key steps are: 

  · Step 1: Make observations. 

  · Step 2: Formulate a hypothesis. 

  · Step 3: Test the hypothesis through experimentation. 

  · Step 4: Accept or modify the hypothesis. 

  · Step 5: Development of a law and/or theory. 


  scientific method
• focuses on understanding basic properties and processes

  Pure research
• focuses on the use of information to create useful materials

  Applied research
• Sometimes there is no clear line between pure and applied research

  true
• properties that describe the physical characteristics of a substance and not how the substance behaves chemically. Examples: melting point, boiling point, density, viscosity, solubility, malleable, solubility, and frequency.


  physical properties
• properties of a substance that describe how that substance's chemical composition will change given a specific set of conditions. Examples: flammable, radioactive, oxidizer, corrosive, combustible, toxic, explosive, and pyrophoric

  chemical properties
• have a definite shape and volume

  Solids
• have a definite volume but take the shape of the container

  Liquids
• have no definite shape or volume

  Gases
• is a form of matter that has a constant composition, and properties that are constant throughout the sample

  pure substance
• are physical combinations of two or more elements and/or compounds. Properties of mixtures can change depending upon the relative amount of the components. Components retain their own properties. 

  mixtures
• Elements and compounds are both examples of pure substances.

  Compounds are substances that are made up of more than one type of atom. Elements are the simplest substances made up of only one type of atom.
• is a mixture in which the composition is uniform throughout the mixture 

  homogeneous
• is a mixture in which the composition is not uniform throughout the mixture 

  heterogeneous
• scientific notation

  If the decimal point is moved to the left n places, n is positive. 

  If the decimal point is moved to the right n places, n is negative.
• Convert each number to scientific notation.

  1. 638.4 = 6.384 x 10^2
  2. 0.0374 = 3.74 x 10^-2
  3. 29,482 = 2.9482 x 10^4
  4. 0.000074 = 7.4 x 10^-5
• Convert each ordinary number to scientific notation, or vice versa.

  1. 67,0000 = 6.7 x 10^5
  2. 56.786 = 5.6786 x 10^1
  3. 32,0000 = 3.2 x 10^5
  4. 0.00000657 = 6.57 x 10^-6
  5. 6.22 x 10^-3 = 0.00622
  6. 9.9 x 10^-8 = 0.000000099
• is a physical property found by dividing the mass of an object by its volume

  Density Mass/Volume
• suggested that all matter in the universe was made up of tiny, indivisible, solid objects he called "atomos."

  the contributions of Democritus to atomic theory. 
• states that the total mass of matter is always the same before and after the changes occur. 

  law of conservation of mass
• that a given chemical compound always contains the same elements in the exact same proportions by mass. 

  law of definite proportions
• Dalton's Atomic Theory is the first scientific theory to relate chemical changes to the structure, properties, and behavior of the atom. The general tenets of this theory were as follows: 

  o All matter is composed of extremely small particles called atoms. 

  o Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, and other properties. 

  o Atoms cannot be subdivided, created, or destroyed. 

  o Atoms of different elements can combine in simple whole number ratios to form chemical compounds. 


  Dalton's atomic theory
• What of daltons theory has been modified

  • Atoms are neither the smallest unit of matter nor indivisible. Atoms are composed of subatomic particles.
  • Atoms of a chemical element can have different atomic masses. These atoms are called isotopes.
  • Atoms of different elements can have the same mass. These are called isobars.
  • Atoms do not need to always combine is a simple whole-number ratio.
  • Atoms can be destroyed or created. Example: nuclear reactions
• Explain how elements are organized into the periodic table. 

  · The modern periodic table was based on empirical correlations of properties such as atomic mass; early models using limited data noted the existence of triads and octaves of elements with similar properties. 
• Describe how some characteristics of elements relate to their positions on the periodic table. 

  · The periodic table achieved its current form through the work of Dimitri Mendeleev and Julius Lothar Meyer, both of whom focused on the relationship between atomic mass and chemical properties. 

  · The correlation with the electronic structure of atoms was discovered when H. G. J. Moseley showed that the periodic arrangement of the elements was determined by atomic number, not atomic mass. 
• is the smallest unit of matter that has the properties of a chemical element 

  atom
• is an electrically neutral group of two or more atoms held together by chemical bonds

  molecule
• The cathode ray tube was first invented by

  Sir William Crookes
• showed that atoms contain small, negatively charged particles called electrons. 


  Thomson’s cathode ray tube
• discovered that there is a fundamental electric charge—the charge of an electron. 


  Millikan
• The discovery of radioactivity took place over several years beginning with the discovery of x-rays in 1895 by 


  Wilhelm Conrad Roentgen