CEM 141 MSU Exam 2 Questions And Answers Rated A+ New Update Assured Satisfaction

Which reaction requires the most energy? A. N(g) → N+(g) + e - B. N+(g) → N2+(g) + e - C. F(g) → F+(g) + e - D. F+(g) → F2+(g) + e - - Answer-D. F+(g) → F2+(g) + e - Fluorine has a higher effective nuclear charge than Nitrogen - so it is harder to remove an electron (takes more energy because the electron is more strongly attracted by the nucleus). Effective nuclear charge is the same for F and F+ because the number of protons and core electrons are not changed. However, when the number of electrons is reduced, the repulsion between electrons decreases which results in a decrease in the radius of the electron cloud because the point at which attractions and repulsions are balanced is closer to the nucleus when there is less repulsion. When the radius of the electron cloud decreases, the strength of the attraction between the nucleus and the valence electrons increases which increases the amount of energy required to remove an electron (ionization energy). Which has a larger atomic radius? Mg or Ar and why. - Answer-Mg, because its valence electrons are not as strongly attracted towards the nucleus as those in Ar. The effective nuclear charge on Mg is smaller - on Ar the electrons are more strongly attracted and therefore the electron cloud shrinks in towards the nucleus until the e-e repulsions come into effect. Consider the isoelectronic (they all have the same number of electrons) species Na+, Mg2+, Ne, and F-, which of these has the smallest radius? - Answer-Mg2+ All the species have the same number of electrons - but different number of protons. Mg2+ has the highest proton to electron ratio and therefore the highest effective nuclear charge and the strongest attraction between the protons and electrons - which pulls the electron cloud towards the nucleus until the repulsions take effect.When and where were the carbon and oxygen atoms in your body created? - Answer-Within stars and stellar explosions Iodine exists as molecules of I2 and silicon dioxide exists as an extended network of Silicon-oxygen bonds (similar to diamond). They both are solids at room temperature, but which do you think has the higher melting point and why? - Answer-Silicon dioxide because to melt it you would have to break covalent bonds. Does one molecule of water have a boiling point? - Answer-No Why does one molecule of water not have a boiling point? - Answer-The boiling point is the temperature at which the particles change from liquid to gas. If there is only one particle the words liquid and gas (and solid for that matter) are meaningless. Why do covalent bonds form? - Answer-- Because electrons from one atom are attracted to the nucleus of another atom. - Because the formation of a bond results in a stable system that would require the input of energy to change. Which of the following are correct statements? I. Covalent bonds are interactions within molecules. II. Covalent bonds are interactions between separate molecules. III. LDFs are typically interactions between separate molecules, but can occur within a single large molecule. IV. LDFs are within molecules. - Answer-I. Covalent bonds are interactions within molecules. and III. LDFs are typically interactions between separate molecules, but can occur within a single large molecule.Why are metals shiny? - Answer-Because they absorb photons and re-emit them. Metals have molecular orbitals that are very close together in energy. They can absorb almost any wavelength of light because the gap between the levels is negligible. The absorbed light can then be reemitted. Wavelength (h) - Answer-- the distance from peak to peak - measured in (m) Frequency (v) - Answer-- number of wavefronts per second - measured in (Hz=s^-1) If a reaction occurs between a compound that has a lemon smell and one that has a rose smell what will the product smell like? Lemon Smell+Rose Smell ---> Smell? - Answer-It is impossible to predict the smell of the product. Give the reasoning for your answer. The properties of new substances depend on its molecular structure - the properties are emergent. What is the missing particle in this reaction? 14C--->14N+ - Answer--1e (β-) C (6 protons) → N (7 protons) No change in total mass so the missing particle must have a -1 charge. What reaction is a nuclear fusion reaction? - Answer-41H → 4He + 2+1e