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BIOL 1103K: Chapter 2 Test Review
atoms |
basic structural units of elements, composed of subatomic particles: protons (+) and neutrons (0) in the nucleus and electrons (-) orbiting in shells |
ion |
a charged atom |
How many electrons can the first shell of any atom hold? |
two |
How many electrons can an atom's outer shell (not the first one) hold? |
eight |
What does the atomic number of an atom represent? |
The number of protons and electrons |
If oxygen has an atomic number of 8, how many electrons are in its outer shell? |
six (the other two are in the first shell) |
ionic bond |
occurs when an electron is transferred between atoms, creating positive and negative ions that attract each other, ex. Na+ and Cl- form NaCl (table salt) |
covalent bond (general) |
occurs when electrons are shared between atoms |
nonpolar covalent bond |
occurs when electrons are shared equally between atoms, ex. two H atoms form H2 |
polar covalent bond |
occurs when electrons are shared unequally between atoms, ex. between H and O in H2O |
hydrogen bond |
occurs between polar molecules when H is bonded to O or N, ex. between water molecules |
Polar bonds are hydro_, while nonpolar bonds are hydro_. |
philic, phobic |
Water is an effective solvent because... |
H2O molecules are polar and can therefore disrupt ionic bonds |
water-soluble |
breaks apart readily in water due to being hydrophilic |
hydrophilic |
"water-loving," breaks apart readily in water |
hydrophobic |
"water-fearing," repulsed by water and clumps together in its presence |
How does sweating keep our bodies cool? |
The water in sweat absorbs a large amount of heat and evaporates. |
Water (expands/contracts) when it freezes. |
expands |
acid |
a solution in which there are more H+ ions than OH-; pH is less than 7 |
base |
a solution in which there are more OH- ions than H+; pH is greater than 7
|
buffer |
a type of molecule that helps a solution maintain constant pH by accepting or releasing H+ in response to a pH change, ex. bicarbonate (HCO3-) |
Why do antacids calm an upset stomach?
|
They are basic and neutralize excess stomach acid. |