Download Mid-Term OR Study Guide

Intensified Chemistry Mid-Term Examination Study Guide
OPEN RESPONSE QUESTIONS
Depending on the nature of the question, your responses should either be in an essay format (using complete
sentences and based on scientific/chemical principles) or a mathematical solution (showing all required work,
including all equivalencies, conversion factors and cancellation of units, and considering the sig fig calculation
rules).
1. A student using places 25.0 mL of water in a 50-mL graduated cylinder. A sample of iron is dropped into the
water in the cylinder. The new volume reading is 37.0 mL.
(A) Calculate the volume of the iron sample (Sig Figs!).
(B) If the mass of the sample is 95.53 g, calculate the density of this iron sample (Sig Figs!).
(C) If the true density of iron is 7.874
2.
3.
g
mL
, use your calculated density to determine the percent error in your
measurement (Sig Figs!).
(D) Use the true density given in Part (C) to calculate what the volume of a sample of iron having a mass of
243.75 g should be (Sig Figs!).
Given a mixture of different
 solid substances, you must:
(A) Classify the type of mixture in the tube;
(B) Explain why you classified the mixture as you did by showing your understanding of the definitions of
different types of mixtures;
(C) Write a procedure explaining how you would separate the different substances in the mixture.
You will be expected to complete a table like the one below. Make sure you finish labeling all element symbols
with superscripts for mass number and atomic number as shown for the tritium isotope of hydrogen below
(remember to show on the element symbol if the species is charged if the number of electrons and protons are not
equal):
Symbol
3
1
H
Atomic Number
Mass Number
Number of protons
20
18
Radon-222 has a half-life of 4.00 days?
A) After how many days does
5.
Number of
electrons
1
20
4.
Number of
neutrons
1
32
of a sample of radon-222 remain?
B) Radon-222 undergoes alpha decay. Write the balanced nuclear equation for this decay process.
Be able to summarize Rutherford’s Gold Foil experiments and be able to explain his conclusions about the
structure of the atom.
6.
Be able to complete an AUFBAU CHART: Consider the element barium. Answer the following questions:
(A) What is the element symbol? How many electrons are in a neutral atom of barium?
(B) Draw the orbital notation for barium using up and down arrows.
(C) Write the complete electron configuration for barium. Do not use kernel notation.
(D) Draw the Lewis electron dot notation for barium.
It is entirely possible that you will be given the orbital notation of an element, and you will need to be able answer
questions A, C, and D above, as well as determine the name of the element and the number of electrons in a neutral
atom of that element .
7. Given a family (or group) in the periodic table:
A) Identify the trend for atomic radius as the atomic number increases (moving down the group) or decreases
(moving up a group). Be able to explain this trend as we did in class.
B) What type of charge will the elements in this group tend to achieve?
C) Identify how the atomic radius compares to the ionic radius for a given element in this family. Be able to
explain the difference in radii.
D) Identify the trend for 1st ionization energy as you move up or down a group. That is, will it become easier or
harder to remove a valence shell electron? Be able to explain this trend.
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8.
9.
Using what you have learned about the Valence Shell Electron Pair Repulsion (VSEPR) model, answer the
following questions about the structure of a molecule made from the elements phosphorus (P, electronegativity =
2.19) and fluorine (F, electronegativity = 3.98). Remember to show all charge designations (δ+ and δ-) for all
polar bonds in all formulas, show where shared electrons come from with different symbols (x’s, open and solid
dots, stars, different color dots, etc.), and put loops around shared electron pairs.
(A) Is the bond type between a phosphorus atom and a fluorine atom ionic, polar covalent, or nonpolar covalent?
Show any relevant calculations/reasoning that you use to determine this.
(B) Write the two possible Lewis dot formulas for the molecules that can be formed from these two elements:
Make sure you show with your dots if the central atom of the molecule has been hybridized!
(C) What is the shape of each of the molecules formed (tetrahedral, pyramidal, bent, linear, trigonal pyramidal,
trigonal bipyramidal, octahedral)?
(D) Are these molecules asymmetrical or symmetrical in shape (discuss each one)?
(E) Are the molecules polar or nonpolar overall? Explain your reasoning for each one.
A solution containing barium ions (electronegativity = 0.89) is reacted with a solution containing phosphide
(electronegativity = 02.19) ions.
(B) Will the bond type be ionic, polar or nonpolar covalent? Show any relevant calculations/reasoning that you
use to determine this.
(C) What is the chemical formula of the compound that is formed in this reaction (Include charge designations)?
(D) Draw the complete dot formula, including charge designations.
(E) Could this compound form endothermically? Why or why not?
(F) If this compound forms covalent bonds, draw its structural formula (including charge designations); if it
forms ionic bonds, which element will be reduced?
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