Exam 2 Flashcards
(162 cards)
What makes up the water molecule?
1 oxygen atom, 2 hydrogen atoms bonded together
What is the basic atomic structure for water (molecule)?
- nucleus made up of protons (+) and neutrons (neutral)
- electrons (-) on rings that orbit nucleus
What is the Octet rule?
it is the tendency of atoms to have stability with their electrons, all atoms/molecules ultimately want 8 electrons in their outer shell (valance)
What is h2o’s bond angle?
105 degrees
Whats unique about the h2o molecule?
- universal solvent
- electromagnetic
- three phases (solid, liquid, gas)
What type of bond holds h2o together?
Covalent bonds
What kind of charge does oxygen carry? hydrogen?
O2 has a negative charge, H has a positive charge
What are the type of bonds in the water molecule?
Covalent bonds hold elements together and form when two or more atoms share electrons to fill their outermost electron shells.
Hydrogen bonds occur when the partial positive charge of a hydrogen atom bonds to an electronegative molecule, usually oxygen and creates surface tension
Which is stronger covalent or hydrogen?
covalent
What is cohesion?
when water wants to “stick” and the “glue” is a hydrogen bond. This leads to surface tension that is at the top (water creates a surface).
Water is a ____ molecule? (in terms of polarity)
dipolar
What is dipolar?
an electrically neutral molecule carrying a positive and a negative charge
why is water a polar molecule?
It behaves as an electromagnet where the Hydrogen end has a (+) charge which attracts to a (-) side of another molecule and the O2 has a (-) charge attracting to a (+) end of another molecule
What is the result of water being a polar molecule?
the process of polarity in water dissolves substances that is why water is a universal solvent.
What happens to NaCl in water?
NaCl dissolve because sodium (Na) has a + charge which attracts to oxygens (-) and chloride (Cl) has a - charge which attracts to hydrogens (+) charge.
T/F NaCl individually is dangerous, sodium is a metal and chloride is a gas
True, as individual elements they are very dangerous but together they make up salt
How do water phases change?
One must either remove/add heat energy. If you add heat, molecules move at a faster rate and change from either solid to liquid or (at a much higher temp) from liquid to gas. If you remove heat energy, the opposite occurs the liquid will turn into a solid.
Explain the structure of solid water (ice)
They are hydrogen bonds holding a 3D crystalline structure. The molecules in this state are locked in place and all H bonds are connected
Explain the structure of liquid water
Most molecules/ H bonds are connected in this phase.
Explain the structure of vapor (gas)
In this phase, the molecules are independent “zooming around” and have no H bonds.
What is heat capacity?
the amount of heat required to raise temp of one gram (of any substance) by 1 degree celsius
What does it mean when a substance has a high heat capacity
takes alot of heat to change the substance
What is water’s heat capacity? (is it low or high)
water has a very high heat capacity, due to thermal inertia (hydrogen bonds)
What is an example of water’s heat capacity?
oceans absorb/release huge amounts of heat with very little change in temperature.