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Will Bell #2
Chapter 2 Atoms, Molecules, Life
Terms in this set (94)
Why is the understanding of Chemistry important?
because the interaction between atoms is one of the lowest levels of biological organization.
What is the basic unit of all forms of matter?
What is the atom?
the smallest unit of matter that retains the physical and chemical properties of the element
What are atoms made of?
What are the three most stable subatomic particles?
protons, neutrons, electrons
What are protons?
positively charged particles found at the core, or nucleus, of the atom
What are neutrons?
uncharged particles found at the core, or nucleus, of the atom.
What are electrons?
are light, negatively charged particles that orbit around the nucleus in electron shells
What is a collection of atoms of the same type form
What is is a substance that can't be broken down into other substances by chemical reactions.
4 most common elements
What is the atomic weight?
the number of protons plus the number of neutrons in the nucleus.
What is a isotope?
atoms of the same element which have different atomic weights
What causes isotopes?
The atoms of a particular element having a different numbers of neutrons
What are electron orbitals?
three-dimensional space around the nucleus of an atom where an electron will be found
What are elements looking for?
for path of Least resistance. Closest way to Get to full outer shell
How many electrons to fill outer shell
How many electrons to fill outer shell of hydrogen?
Why elements are looking to fill outer shell?
To become stable.
What is the chemical behavior of an atom determined by?
the number of electrons in the outermost electron shell
An atom with an incomplete (partially full) electron shell is what?
An atom with a full outer shell is what?
Inert, not chemically active
What was the Hindenburg filled with?
What will an atom do if there is a vacancy in its outer shell?
It will try to fill that vacancy or get rid of the "extra" electrons so the outer shell is full.
A reactive atom will do what?
try to fill the valence shell by interacting with other atoms.
What is a chemical bond?
an attraction that holds two atoms together.
What is a molecule?
two or more atoms held together by chemical bonds.
A molecule is the smallest unit that does what?
The smallest unit that retains the physical and chemical properties of a compound.
similar atoms become what
molecules then elements
different atoms become what
molecules then compound
When are ions formed?
If an atom has an almost empty or an almost full outer electron shell it is more likely to form an ion
What is a ion?
a charged atom or molecule. It is charged because it has either lost or gained electrons
Whats a anion?
is a negatively charged atom or molecule. It has gained an electron.
Whats a cation?
a positively charged atom or molecule. It has lost an electron.
Ionic Compounds are called what?
Ionic Compounds form what in the solid state?
Ionic Compounds are strong in what? But break easily is what?
crystals and weak in water.
Salt dissolves in what?
Ionic bonds do what in water?
break up easily in water
What is a covalent bond?
is a bond formed when two atoms share pairs of electrons.
What are 2 types of covalent bonds?
polar and non-polar
What is a non-polar covalent bond?
a covalent bond in which the sharing of the electron pair is equal
What is a polar covalent bond?
is a covalent bond in which the sharing of the electron pair is unequal.
Polar will only dissolve in what? Non-polar dissolve with what?
Polar will only dissolve in polar, non-polar will dissolve only in non-polar
What is the electronegativity?
as an atom's ability to attract and hold electrons. An indication of how much positive charge is in the nucleus. Assigned a numerical value. The higher the #, the more electronegative an atom is.
Electronegativity for Hydrogen, Nitrogen, Carbon, Oxygen
Atoms with a higher electronegativity have higher what? and will do what?
more-postivitly charged nucleus and will hold onto the electron pair more strongly than atoms with significantly lower electronegativity.
What is formed by the charge attraction when a hydrogen atom which is covalently bonded to one atom is attracted to a second atom.
Cells are what % water?
Water covers what percent of Earth?
What are the most biologically important polar covalent bonds?
Water is what type of molecule
Some of the most important polar covalent bonds are what?
bonds in water molecules
What makes water a very versatile solvent?
polarity along with the hydrogen bonding
What kind of molecule is water?
Polar and Ionic Substances are easily dissolved in water which makes them what?
What is the hydrophilic?
describes the property of having an affinity for water.
what makes water a poor solvent for molecules which do not have charged regions?
polarity of water
Nonpolar substances are what
What does Hydrophobic describe?
the property of not having an affinity for water.
What do hydrophobic molecules do because of hydrophobic interaction?
Why does oil not dissolve?
because the nonpolar oil molecules cannot form hydrogen bonds with the polar water molecules
Attraction between like molecules
Water molecules tend to do what?
Why does water have a cohesive behavior?
because of the result of hydrogen bonding between the water molecules and the other molecules
What is surface tension?
cohesion among water molecules at the surface of water.
Cohesion causes what?
What can water molecules do?
What does it mean when a water molecule dissociate?
means that the hydrogen atom of one water molecule leaves its electron behind and forms a hydrogen ion (H+) and a hydroxide ion (OH-).
When do the number of (H+) ions = the number of (H-)?
When is a solution more acidic?
the number of H+ ions is greater than the number of OH- ions.
When is a solution more basic?
if the number of OH- ions is greater than the number of H+ ions
What does it mean to be a proton donor?
a substance which increases the concentration of H+ in a solution.
Is an acid a proton donor or receptor?
Is an basw a proton donor or receptor?
What does it mean to be a proton receptor?
a substance which reduces the concentration of H+ in a solution
What is used to measure the acidity of solutions?
Describe the ph scale
For a neutral solution pH = 7
For an acidic solution pH < 7
For a basic solution pH > 7
Most biological solutions are between what on the pH scale
the pH scale is what kind of scale? What does it mean?
Logarithmic.A change of one pH unit represents a tenfold change in the concentration of H+
What helps maintain a constant pH?
What are buffers?
are substances that prevent large, sudden changes in pH.
Buffers are a combination of what?
are combinations of H+ donors and H+ acceptors
How do Buffers function?
function by accepting H+ ions from solution when they are in excess, and donating H+ ions to the solution when the supply is depleted.
What helps to moderate the effect of changes in temperature?
What three properties of water help keep temperture stable?
1. High specific Heat
2. High heat of vaporization
3. High heat of fusion
What is the specific heat?
the amount of energy that must be absorbed or lost for one gram of matter to change its temperature by one degree Celsius.
What is the specific heat of water? alcohol? table salt?
water= 1 calorie/gram
alcohol= 0.6 calorie/gram
table salt= .2 calorie/gram
rock= 0.02 calorie/gram
Water has a high what? and what does this do surfaces as water evaporates?
Heat of Vaporization
cools the surface
What is vaporization?
(evaporation) is the transformation of matter from a liquid to a gas.
Heat of Vaporization is defined as?
is the quantity of heat a liquid must absorb for 1 gram to be converted to the gaseous state, or to evaporate.
How does the temperature of a liquid change?
The "hottest" molecules, which have the highest kinetic energy leave the liquid. As a result the average temperature / kinetic energy of the liquid drops.
Why does ice floats?
Water is more dense in the liquid form than in the solid form. This is why ice floats.
Water has a high heat of? Which causes it do what?
Fission, freezes much slower than other liquids.
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