Chem Unit Test 1 Flashcards
What would be the state of an ionic compound at 25 degrees celsius?
solid
What would be the state of a molecular compound at 25 degrees celsius?
solid, liquid, or gas.
Give an example of a solid at room temperature molecular compound?
Sugar C12H22O11
Give an example of a liquid at room temperature molecular compound?
Water H2O
Give an example of a gas at room temperature molecular compound?
Oxygen O2
Are the melting points of ionic compounds high or low?
high
Are the melting points of molecular compounds high or low?
low
Describe the conductivity of ionic compounds.
They are electrolytes (conduct an electric current when dissolved in water). Not conductive in solid form.
Describe the conductivity of molecular compounds.
They are nonelectrolytes. (Except acids and bases).
Describe the solubility of ionic compounds.
Most are soluble.
Describe the solubility of molecular compounds.
Most aren’t soluble.
What happens when a molecular compound melts?
Its intermolecular forces break.
What are intermolecular forces?
The forces between the atoms in a molecule.
Why do ionic compounds have higher melting points than covalent compounds?
Because ionic bonds are much stronger than intermolecular forces.
Who discovered electronegativity?
Linus Pauling.
Why are ionic compounds stronger than covalent compounds?
Because opposite charges attract.
What is electronegativity?
The tendency of an atom to attract electrons in a covalent bond.
What does the electronegative difference have to be in order to indicate a non polar covalent compound?
0
What does the electronegative difference have to be in order to indicate a polar covalent compound?
more than 0 less than 1.7.
What does the electronegative difference have to be in order to indicate an ionic compound?
over 1.7.
What do the dipole moments point to?
The element with the greater electronegativity.
What does the length of the dipole moment correspond to ?
The electronegativity.
How does one tell if a molecule is polar judging by the diagram?
If it is asymmetrical. (all atoms around central atom are not the same or lone pairs around central atom).
What two factors do the melting points of molecular substances depend on ?
- The type of intermolecular force.
2. The size of the molecule.
What are the 3 types of intermolecular forces?
- H-bonds (polar)
- Dipole-dipole (polar).
- London forces (polar and non-polar)
How to tell if a polar molecule has Hbonds or dipole dipole forces?
If the hydrogen is bonded to O, N, or F it has Hbonds. If not, it has dipole-dipole forces.
How does the size of the molecule affect the strength of london forces?
London forces become stronger as molecular size increases.
Which typically have have higher boiling points: polar or non-polar compounds?
Polar compounds. Because they have Hbonds or dipole-dipole forces ALONG with the london forces.
Why do ionic solutions conduct electricity?
When it dissolves in water, the ions separate.
Why don’t molecular solutions conduct electricity?
Because the molecules separate but no ions are produced.
What lets something conduct electricity?
The movement of ions.
give an example of a word equation for NaCl.
Sodium + Chlorine = Sodium chloride.
Give an example of a skeleton equation for NaCl.
Na + Cl = NaCl.
Write the balanced equation for NaCl.
2Na + Cl2 = 2NaCl.
What is the Law of Conservation of Mass?
In any chemical reaction, the mass of the products is equal to the mass of the reactants.
What is the synthesis reaction?
A + B = AB
What is the decomposition reaction?
AB = A + B
What is the Single deplacement reaction?
A + BC =AC + B
What is the Double deplacement reaction?
AB + CD = AD + CB.
What does an acid separate into?
A non-metal oxide + water.
What does a base separate into?
A metal oxide + water.
What does a metal hydroxide separate into?
Metal oxide + Water.
What does a metal nitrate separate into?
Metal nitrite + oxygen.
Is methane polar or non-polar?
NON-POLAR!!!!!!!!!!
When do you use the electronegative difference to determine if a covalent compound is polar/non-polar/ionic.
When the compound only contains two elements.
Which are stronger: covalent bonds or H-bonds?
Covalent bonds.
What is a covalent bond?
A chemical bond that involves the sharing of electron pairs between atoms.
