Name: ___________________________________ Group: ____________ Period: _____
Chapter 5
Activity 2 – Solid, Liquid or Gas?
What Do You See? – pg 361
What Do You Think? – pg 361
What makes a gas different from a liquid or a solid? Why are some substances gases at
room temperature while others are not?
Investigate – Part A
Part A: Size and Shape of Molecules
1) Look at the pictures of molecules on page 361 and 362.
There are 4 different groups:
-Diatomic Halogen Molecules
-CX4 molecules (where X= H,F,Cl,Br)
-Hydrocarbons
-Alcohols
2)
a) What do you notice about the shape of the diatomic
halogen molecules? How do their sizes compare?
_______________________________________________
_______________________________________________
b) What do you notice about the shape of the CX4 molecules?
How do their sizes compare?
_______________________________________________
_______________________________________________
c) The hydrocarbon and alcohol molecules are similar. CH4 is
methane and CH3OH is methanol. C2H6 is ethane and
C2H5OH is ethanol. The other pairs are propane and
propanol and butane and butanol. What is the difference
between each of the pairs of molecules? Look carefully at
their shapes. Describe any differences that you notice.
_______________________________________________
_______________________________________________
Part B: Boiling and Melting point of Molecules
Read the paragraph on pg 362 under the above heading and answer
the following questions:
1) Room Temperature is about________?
2) If a substance has a boiling point below room temperature, it
must be a solid, liquid or gas at room temperature?_______ .
3) If a substance boiling point is above room temperature then it
is a solid, liquid or gas?______________________________.
2
4) If a substances melting point is above room temperature,
then it is a solid, liquid or
gas?____________________________.
1) Look at the table showing the melting and boiling points of
halogens on page 363.
a) Read the information and answer the questions in the
chart provided:
Halogens that are:
Gases at Rm. Temp Liquids at Rm. Temp Solids at Rm. Temp
b) Since all halogens are the same shape, what is the
difference between those that are gasses at room temp
and those that are liquids or solids at room temp?
_________________________________________________
________________________________________________
2) Look at the table showing the melting and boiling points of CX 4
compounds on page 363.
-
Read the question and answer in the chart provided.
CX4 compounds that are:
Gases at Rm. Temp Liquids at Rm. Temp Solids at Rm. Temp
3
b) Since all CX4 moleculas are the same shape, what is the
difference between those that are gasses at room temp
and those that are liquids or solids at room temp?
________________________________________________________
___________________________________________________.
3) Read the paragraph on page 363 at this step and answer these
questions.
-Hydrocarbons are made up of____________________.
-Alcohols contain______________________________.
-What combination of atoms is in both of these molecules
CH3OH, NaOH? _______________________________.
-How is the alcohol bonded? ____________________.
-What is NaOH? A molecule or an ionic compound? (circle).
a) Look at the graph showing the boiling points of
hydrocarbons and alcohols on page 364. Answer the
question in the chart provided.
Hydrocarbons that are gases
at room temp.
Hydrocarbons that are liquids at
room temp.
4
b) What is the general trend in boiling points of hydrocarbons as the
number of carbons increases?
________________________________________________________
________________________________________________________
________________________________________________________
c) Compare:
- Methane/ Methanol
- Ethane/Ethanol
- propane/1-propanol
- butane/1-butanol
What factor could contribute to the large difference in boiling points for
each pair?
________________________________________________________
________________________________________________________
________________________________________________________
__.
4) Based on the answers of the above questions, what are the general
contributing factors that help you decide whether a molecule is a solid,
liquid or gas at room temperature?
___________________________________________________
___________________________________________________
___________________________________________________
5
___________________________________________________
__.
Explain what the factors you listed tell you about a substance
boiling point.
___________________________________________________
___________________________________________________
___________________________________________________
___________________________________________________
___________________________________________________
____.
Chem. Talk Notes (Pg 364-366)
Define:
1. Intermolecular forces
2. Non polar molecule
3. Polar molecule
4. London Dispersion Forces
6
5. Electronegativity
6. Polar bond
Checking Up Questions (pg. 366)
1)______________________________________________________
________________________________________________________
________________________________________________________
_.
3)______________________________________________________
________________________________________________________.
Part C
Your teacher will show you some simulations of different types of
intermolecular attractive forces. For each one, sketch the forces,
explain how they work, and classify them as strong or weak.
http://intro.chem.okstate.edu/AP/Inter-IntraHandout.html
7
8
Part D _ Valence Shell Electron Repulsion Theory
Draw lewis dot structures for the following molecules
CH4
NH3
H2O
1. An electron domain is defined as either a bond or a lone pair of
electrons. How many electron domains are located around the
central atom of each molecule?
2. If each atom is sharing eight valance electrons, what are
differences in these 3 molecules?
3. Using a molecular modeling set, create models of CH4, NH3 and
H2O. Remember to include the lone pairs in your model.
4. Do the lone pairs have an effect on the shape of your molecule?
Explain.
5. Compare your 3 models –what are the similarities and
differences.
9
There are different shapes that a molecule can form depending on the
amount of bonds and lone pairs around the central atom. Your teacher
will help you complete the chart below.
Total
number of
electron
domains
Number of
bonding
pairs
Number of
non bonding
(lone) pairs
Molecular
shape
Sketch
6. How might the shape of a molecule affect the polarity?
7. Is it possible to have polar bonds in a non-polar molecule?
Explain.
8. How might the shape/symmetry of a molecule affect its boiling
point?
10
9. Predict the shape and polarity of the following molecules. If a
molecule does not have polarity, write non-polar.
Molecule
Structure
(sketch). Include
lone pairs
Shape
Polarity
(represent with
an arrow, with
the head toward
the negative part
of the molecule)
H2O
HF
Cl2
CCl4
NH3
CH4
CF4
CH3Cl
CH2Cl2
CO2
11
10. Which molecules were polar because all bonds were non
polar?
11. Which molecules had polar bonds but were non polar
because of symmetry?
12.
Which 2 shapes appear to produce polar molecules?
Chem To Go (pg368)
2)______________________________________________________.
3a)_____________________________________________________
______________________________________________________.
3b) Which one is liquid at room temp.?_________________________.
4.
5.
6. a)
b)
c)
12