Chem 105 Exam 1

Describe the contribution of Marie Curie to our understanding of atoms

Curie discovered radioactivity, demonstrating that atoms are not immutable.

Describe the contribution of Dalton to our understanding of atoms

Dalton proposed an atomic theory, identifying atoms as tiny, indivisible structures that form the basis of matter, and elements as distinguishable by their atomic masses.

Describe the contribution of Millikan to our understanding of atoms

Millikan's oil drop experiment helped us calculate the mass and charge of an electron.

Describe the contribution of Rutherford to our understanding of atoms

Rutherford fired a beam of alpha particles (He nuclei) through a thin metal foil to test Thompson's plumb pudding model. He expected the alpha particles to pass essentially undeflected; however, some were deflected at large angles sometimes right back at the source. He determined that the atom consisted of small nucleus with most of the mass and the positive charge, while the majority of the volume of the atom contained the much less massive electrons of negative charge.

Describe the contribution of Thompson to our understanding of atoms

Thompson used the cathode ray tube to discover that there were subatomic particles, namely the electron.

Define the Law of Multiple Proportions

When two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers

Which of the following statements regarding orbitals and wave functions is true? a. Wave functions are mathematical solutions to the Schrödinger wave equation. b. Wave functions specify where an electron is at any given time. c. An orbital encloses a region in space around the nucleus where the probability of finding an electron is 1. d. The square of the wave function describes how the electron matter wave varies in time and space. e. All sine functions are solutions to the Schrödinger equation for the hydrogen atom.

a. Wave functions are mathematical solutions to the Schrödinger wave equation.

According to the law of definite proportions... a. atoms forming a given compound react in variable proportions depending on conditions. b. different samples of the same compound contain the same proportions of the same elements. c. all compounds containing the same types of atoms have identical properties. d. all compounds containing the same types of atoms have relative masses that are whole-number multiples. e. only one type of molecule can be produced when two elements combine.

b. different samples of the same compound contain the same proportions of the same elements.

An element.... a. can be separated into its components by physical methods. b. always has the same chemical properties regardless of its source. c. cannot be separated into simpler substances by chemical methods. d. can also be a compound. e. exists only as atoms, not as molecules.

c. cannot be separated into simpler substances by chemical methods.

Which of the following statements regarding the Bohr model of the atom is NOT correct? a. Changes in the energy of the atom involve the electron transitioning between allowed orbits. b. The atom has discrete energy levels described by a quantum number, n. c. The electron does not radiate energy and spiral into the nucleus if it is in an allowed orbit. d. The atom has zero energy when in its ground state. e. The energy of an orbit is inversely proportional to n2.

d. The atom has zero energy when in its ground state.

Which of the following statements is NOT true regarding blackbody radiation, the ultraviolet catastrophe, and Planck's view of electromagnetic radiation? a. A blackbody radiator does not absorb and emit one wavelength preferentially over another. b. The emission spectrum of a blackbody radiator depends on its temperature. c. A blackbody radiator cannot emit an infinite amount of radiation. d. Planck theorized that real objects can only absorb or emit discrete packets of electromagnetic radiation. e. The ultraviolet catastrophe disappears if emission spectrum of a blackbody radiator is continuous.

e. The ultraviolet catastrophe disappears if emission spectrum of a blackbody radiator is continuous.

Define the Law of Definite Proportions

the fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound