Chem 1061: Unit 1

• What is the difference between a scientific theory and a theory?

  A theory is any type of guess, but a scientific theory need evidence through data collection and experimentation to explain the how or why. They also have to make testable prediction and be falsifiable.
• Which of the following have atoms in it: heat, cells, air, or gold?

  cells, air, gold
• Why doesn't heat contain atoms?

  Heat is not matter, it is energy, therefore does not contain atoms
• What is the approximate scale of an atom and an element?

  An atom: nm, an element: cm
• What is the smallest unit of an element?

  An atom
• What is the plum pudding model?


  electrons are embedded in a positively charged atom
• What is evidence for the existence of an electron?

  The cathode ray tube showed that particles would travel from the cathode to he anode and that the particles were deflected by electric fields which indicated a negative charge. Particles carried electrical charge. Results remained the same despite type of metal, so it was generalized to all atoms
• Planetary Model


  nucleus with orbiting electrons
• Evidence for concentrated nucleus


  Alpha particles were shot at a gold film. Some particles were deflected, but some went through. Determined that most of the atom is concentrated into a small, dense, nucleus
• What is an isotope?

  An element with the same number of protons and electrons, but a different number of neutrons.
• What happens when two atoms of He approach each other?

  Initially, there is attraction by the coulombic forces of the LDFs. Then the electron clouds overlap and repel. This causes the KE energy to initially increase, but then it increases and the atoms move away.
• Does Xe or He have a higher boiling/melting point?

  Xe
• What's the difference between gravitational and electrostatic forces?

  Gravitational forces are responsible for attraction based on mass of an object. Electrostatic forces are what causes attraction and repulsion of charged objects.
• What is the ground state electron configuration of S?

  [Ne]$3s^23p^4$
• What is the ground state electron configuration of Se?

  [Ar]4s23d104p4
• What is the ground state electron configuration of Sn?

  [Kr]5s24d105p2
• Order the following elements by increasing size: K, P, N, Cs?

  N, P, K, Cs
• Order the following elements by decreasing size: $Ar, Cl^-, Cl$


  $Cl^-, Cl, Ar$
• T or F: n=3 to n=1 is an example of an electron transition that corresponds to the absorption of energy?

  F
• T or F: n=4 to n=7 is an example of an electron transition that corresponds to the absorption of energy?

  T
• Determine the mass of a rock (in g) with a wavelength of 2.44 x 10-33 m moving at 2.89 m/s.

  94
• Determine the energy (in kJ/mol) of one mole of photons with a wavelength of 623 nm.

  192.14
• Which phenomena are evidence that light behaves as a particle? Select all that apply: Diffraction, constructive interference, destructive interference, photoelectric effect, double slit experiment 

  Photoelectric effect
• Rank the following elements in order of increasing ionization energy (IE1) : Te, F, Rb, S


  Rb, Te, S, F
• Ionization energy is the energy required to pull an electron away from the attractive electric force of the nucleus. The stronger the force, the more energy is required -- that is, the higher the ionization energy.
• What to factors determine the strength of an electric force? (Relates to IE)


  The magnitude of the electric charge, the distance between electric charges
• Determine the speed (in m/s) of a tennis ball (m= 56 g) with a wavelength of 8.6 x 10-33 m.

  1.38
• What is the bond order equation?

  $o=$$(n-n^*)/2$
• What type of molecules are stable?


  Only molecules with a bond order greater than zero are stable
• When is a molecule paramagnetic?

  If it has unpaired electrons
• Is $O_2^-$stable?


  yes
• is $Ne_2^+$diamagnetic or paramagnetic?


  paramagnetic
• What is the bond order of $Ne^+$$_2$?


  3/2
• What is A?


  mass number
• what is Z?


  atomic number
• what is the mass number?

  The number of protons + number of neutrons
• What is ΔHrxn?


  Standard enthalpy of reaction
• What states are there London Dispersion Forces?


  liquid and solid states, but not the gas state.
• Determine the mass of X (in g) produced when 3.94 g of Y and 7.49 g of Z are reacted.

  Y + 3 Z ⟶ A + 2 X

  Molar masses:

  A = 101.55 g/mol

  X = 87.63 g/mol

  Y = 63.42 g/mol

  Z = 109.89 g/mol

  3.98
• Using the balanced reaction below, determine the number of moles of CO2 that can be formed from 9 moles of I2O5 and 5.8 moles of CO.

  5 CO(g) + I2O5(s) →  I2(s) + 5 CO2(g)

  5.8