Recall

• What is the first rule of safety in the chemistry laboratory?


  Safety is everyone's responsibility.
• Why is social distancing important in the laboratory?


  To maintain safety while conducting labs.
• What personal protective equipment (PPE) should be worn in the lab?

  Lab gowns, safety goggles, closed-toe shoes, and long pants.
• What should you do if you break glassware in the lab?

  Properly dispose of it and report it.
• What should you never do in the lab regarding food and drink?

  Do not eat, drink, or taste anything.
• What is the purpose of wafting when smelling chemicals?


  To safely detect odors without directly inhaling them.
• What should you do with unused solids in the lab?

  Do not return them to their reagent bottles to avoid contamination.
• How can a precipitate be separated from a solution?


  By decantation or filtration.
• What is the definition of a precipitate?


  A solid formed in a solution during a reaction.
• What is the first step in decanting a liquid?

  Allow the solid to completely settle to the bottom of the container.
• What should you assume about all chemicals in the lab?

  Assume all chemicals are dangerous.
• What is the purpose of the Hazard Communication Standard (HCS)?


  To require pictograms on labels to alert users about chemical hazards.
• What are the classifications of chemical hazard symbols according to the NFPA?

  • White: Specific hazard
  • Yellow: Reactivity
  • Blue: Health hazard
  • Red: Flammability
• What is the capacity of a Triple Beam Balance?


  About 610 g.
• How do you use a Top Loading Balance?

  Turn it on, wait for it to read 0.000 g, and place the sample container on the pan.
• What is the purpose of an Analytical Balance?

  For very accurate, quantitative mass measurements to the nearest 0.0001 g.
• What are the common types of laboratory glassware and their uses?

  1. Beakers: For holding and mixing liquids.

  2. Test tubes: For holding small amounts of liquids.

  3. Erlenmeyer Flask: For transporting and storing substances.

  4. Graduated Cylinder: For measuring liquids.

  5. Volumetric Flask: For precise volume measurements.

  6. Florence Flask: For holding and heating liquids evenly.

  7. Pipette: For delivering specified volumes of solutions.
• What is the function of a Bunsen burner?

  For heating chemical mixtures or contents in the lab.
• What is the purpose of a Mortar & Pestle?


  To grind chemicals or substances into powder form.
• Who proposed the atomic theory that all matter is made up of atoms?

  John Dalton.
• What did J.J. Thompson discover?

  The electron, the smallest sub-atomic particle.
• What is the significance of Ernest Rutherford's Gold Foil Experiment?


  It showed that the atom is mostly empty space with a tiny, dense, positively charged nucleus.
• What is the Planetary Model proposed by Niels Bohr?

  It proposed that electrons revolve in stable orbits around the nucleus.
• What are isotopes?

  Atoms of the same element with different mass numbers.
• What is the difference between cations and anions?

  Cations are positively charged, while anions are negatively charged.
• What is the atomic number represented by in an element symbol?


  Z (atomic number).
• What does the mass number represent in an element symbol?


  A (mass number) represents the total number of protons and neutrons in an atom.
• How did the views of Democritus and Aristotle differ regarding atomic theory?


  Democritus believed in indestructible atoms, while Aristotle believed matter was made of four elements.
• Who discovered the proton?

  Ernest Rutherford
• What did the Gold Foil Experiment demonstrate about the atom?

  It showed that the atom is mostly empty space with a tiny, dense, positively charged nucleus.
• Who proposed the concept of discrete energy levels for electrons?

  Niels Bohr
• What is the Planetary Model of the atom?

  It describes electrons revolving in stable orbits around the nucleus.
• What are valence electrons?


  They are the outermost electrons of an atom.
• How can you determine the group number of an element?

  By identifying the number of valence electrons it has.
• Who formulated a wave equation for calculating energy levels of electrons?

  Erwin Schrödinger
• What do quantum models of the atom describe?

  They describe electron behavior as a cloud rather than fixed orbits.
• Who proved the existence of neutrons?

  James Chadwick
• What are neutrons?

  Elementary particles devoid of any electrical charge.
• What is the relationship between protons, neutrons, and atomic mass?

  Atomic mass is the sum of protons and neutrons in an atom.
• What is a cation?

  A positively charged ion that loses electrons.