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LIGUORI TEST LATEST UPDATED
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LIGUORI TEST LATEST UPDATEDatomic number - ANSWER the number of protons in the nucleus of an atom,
identifies which element the atom belongs to and the number of the element on the
periodic table
mass number - ANSWER the sum of the number of neutrons and protons in an
atomic nucleus, number on the bottom of a periodic table square
rows of the periodic table - ANSWER also known as periods; are made up of
elements that have the same number of electron shells or energy levels. the higher
up the row upon which the element is placed, the lesser the attraction is between
the atomic nuclei of atoms belonging to that element; and therefore the more
reactive the element is.
valence electrons - ANSWER Electrons on the outermost energy level of an atom.
The number of them that exist as well as their proximity to the atomic nucleus
determine the reactivity of the atom.
electronegativity - ANSWER the ability of an atom to attract electrons from other
atoms in a compound when the atom is in a compound. oxygen is one of the most
______________ elements.
electronegativity difference - ANSWER the difference in electronegativity between
two atoms in a bond; determines polarity. <0.5 = covalent bond; >1.5 = ionic bond;
0.5 - 1.5 = polar covalent bond
polarity - ANSWER A lack of electrical symmetry in a molecule; slight charge
differences on opposite ends of a structure. Occurs due to electronegativity
differences between the atoms in a compound, or due to the asymmetry of the
compound. Water is very polar.
ion - ANSWER A charged atom. Atom is charged because it has fewer electrons
than protons (positively charged cation) or because it has more electrons than
protons (negatively charged anion)
cation - ANSWER A positively charged ion
,anion - ANSWER A negatively charged ion
ionic bond - ANSWER A chemical bond resulting from the attraction between
oppositely charged ions. A common misconception about these is that the bond
occurs because one atom 'steals' an electron from another; this is not true; the bond
occurs because of the very strong attraction between the atoms that results after the
electron stealing. Salts are bound this way.
covalent bond - ANSWER A chemical bond that involves sharing a pair of
electrons between atoms in a molecule
polar covalent bond - ANSWER A covalent bond between atoms that differ in
electronegativity. The shared electrons are pulled closer to the more electronegative
atom, making the more electronegative atom slightly negatively charged and the
other atom slightly positively charged.
hydrogen bonds - ANSWER Very weak bonds. in water, these occur when a
hydrogen atom in one water molecule is attracted to the oxygen atom in another,
this attraction occurring due to the slight positive charge in the hydrogen atom, and
the slight negative charge in the oxygen atom (these slight charges occur because
oxygen is very electronegative and hydrogen is not)
cohesion - ANSWER Attraction between molecules of the same substance,
especially water. Occurs in water due to the hydrogen bonding in water. Helps pull
water from the bottom of plants to the top -- evaporating water at the top pulls all
the other water towards the top with it.
water's high surface tension - ANSWER Phenomenon where water molecules at the
surface cling more tightly to each other than to the air above due to the hydrogen
bonds in water. Very light things can walk on water because the force they exert on
the water is not enough to break _____________________.
adhesion - ANSWER An attraction between molecules of different substances. In
water, this happens when water is attracted (sticks to) another polar or hydrophilic
substance. Allows water to move up xylem channels in plants.
hydrophilic - ANSWER water-loving; attracted to water; usually because of
polarity (polar substances like water are attracted to other polar substances)
hydrophobic - ANSWER water-hating. Water will clump to itself if presented with
, a substance that is this instead of sticking to the substance, remember the plastic
activity liguori had us do. Substances that are this include lipids, oils, and fats.
water's ability to moderate temperature - ANSWER occurs because water can
absorb heat from warmer air and release stored heat into cooler air, and can absorb
or release large amounts of heat with only a slight change in its own temperature
(high specific heat).
specific heat - ANSWER The amount of energy required to raise the temperature of
1 gram of a substance by 1 degree Celsius. Water has a very high one of these.
ice's density - ANSWER less dense than water because the hydrogen bonds in
water expand upon cooling to form a lattice structure, molecules are more spread
out. The solid form of water being less dense than the liquid form of it is very
important to biology because marine life would never survive winter (or summer,
for that matter) without that property; rather than floating, frozen water would sink
to the bottom of a body of water, killing all life in it.
pH - ANSWER the concentration of hydrogen ions in a solution. a pH of 1-7
denotes an acidic solution, 7 is neutral pH, 7+ denotes a basic or alkaline solution.
hydroxide ions / OH- - ANSWER these ions are found in high concentrations when
the solution is basic
buffer - ANSWER weak acid or base that can react with strong acids or bases,
neutralizing them and helping prevent sharp, sudden changes in pH
homeostasis - ANSWER A tendency to maintain a relatively balanced and constant
internal environment that is optimal for life, allows for life to flourish.
negative feedback - ANSWER A primary mechanism of homeostasis, whereby a
change in a physiological variable that is being monitored triggers a response that
counteracts the initial fluctuation. Allows for the maintenance of homeostasis.
positive feedback - ANSWER A physiological control mechanism in which a
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