✨
5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
AP Biology Review
UNIT I: CHEMISTRY OF LIFE
A. Elements
All life forms made up of matter
All matter made up ofelements
Elements
Substances that cannot be broken down into smaller substances
by chemical means
B. Essential Elements of Life
96% of the mass of all living things made up of 4 elements:
Oxygen(O)
Carbon(C)
Hydrogen(H)
Nitrogen(N)
Other elements (collectively 4% of biomass)
Calcium (Ca)
Phosphorus (P)
Potassium (K)
Sulfur (S)
Sodium (Na)
Chlorine (Cl)
Magnesium (Mg)
Trace elements
IRon (Fe)
Iodine (I)
Copper (Cu)
C. Subatomic Particles
Atom
Smallest unit of an element
Building blocks of physical world
Subatomic PArticles
Protons
Packed with neutrons in nucleus
Positively charged
Most atoms have same amount of protons as electrons, making them
electrically neutral
Neutrons
Packed with protons in nucleus
No charge
Isotopes
Same element with different amount of neutrons in nucleus
Vary in mass
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5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
adioactive isotopesdecay spontaneously, giving off particles
R
and energy
Electrons
Negatively charged
Spin around nucleus
Very small; effectively massless
Electrons on an atom differ in their amounts of potential energy
Electron’s state of potential energy is called its energy level, orelectron
shell
Valence electronsare those in the outermost shell,orvalence shell
Chemical behavior of an atom is mostly determined by the distribution of
electrons in electron shells
Valence shell most important
Elements with full valence shells are chemicallyinert
Atoms with incomplete valence shells can share or transfer
valence electrons with certain other atoms
Atoms of different various elements differ in number of subatomic particles
Atomic number=#protons in nucleus
Mass Number= protons+neutrons
Average of all isotopes
Atomic mass+atom’s weighted average total mass
D. Compounds
Compoundoccurs as result of 2 or more individualelements combining in a fixed ratio
Different properties of individual elements
Formed by chemical reaction
Bonds that hold compounds together
Ionic bonds
nonmetal+metal
One or more electrons is transferred from one atom to another
One atom loses electrons (becomes positively charged) while the other
gains electrons (becomes negatively charged)
Results from attraction of two oppositely charged ions
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5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
ationhas a positive charge
C
Anionhas a negative charge
Cation and anion form to create ionic bond
Covalent bonds
nonmetal+nonmetal
Moleculeconsists of 2 or more atoms held togetherby covalent bonds
Formed when electrons are shared between atoms
Innonpolar covalentbond, electrons are shared equally
Inpolar covalentbond, electrons are shared unequally
In asingle covalent bond, one pair of electrons isshared
Double covalent when 2 pairs are shared, etc.
Structural formulaused to represent atoms and bonding
Ex. H-H
Molecular formulaabbreviates structural formula
Ex. H2
lectronegativityis an atom’s attraction for theatoms in a
E
covalent bond
The more electronegative an atom, the more strongly it
pulls shared electrons toward itself
Hydrogen bonds
Hydrogen atom covalently bonds to one electronegative ato is also
attracted to another electronegative atom
In living cells, hydrogen bonds are usually oxygen or other nitrogen
atoms
Van der Waals Interactions
Weakest
If electrons are distributed asymmetrically in molecules or atoms, they
can result in “hot spots” of positive or negative charge
Attractions between molecules that are close together as a result of these
charges
How geckos climb
. Water: The Versatile Molecule
E
In water, electrons are not shared equally in the bonds between hydrogen and oxygen
Hydrogen atoms have a partial positive charge while oxygen atoms has a partial
negative charge
Water is polar
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5
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5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
Hydrogen bonds
Weak attractions that result of water’s polarity
Positive end of another polar molecule attracted to oxygen negative
charge, and vice versa with the hydrogen end
Hydrogen atom covalently bonded to one electronegative atom is also
attracted to another electronegative atom
Weak Individually, but strong on a larger scale
Lends watermany special properties
Cohesion
Tendency for water to stick to water
Important during transpiration
Water evaporates, pulls other water molecules with it,
pulling all the way down from leaves to roots
Adhesion
Tendency of water to stick to other substances
Cohesion + Adhesion =capillary action
Allows water to flow up roots/trunks/branches of trees in
thin vessels
Surface tension
Results from cohesion of water molecules
Ex. water striders can sit on top of water without sinking
High heat capacity
Heat CApacity=ability of a substance to resist temperature
changes
Keeps ocean temperatures stable
Allows organisms to keep constant body temperature, since most
life forms are mostly made up of water
Heat is absorbed when hydrogen bonds break, released when
hydrogen bonds form
High heat of vaporization
Heat a liquid must absorb for 1g to be converted to gas
STAR AP CRAM ACADEMY DOES NOT TAKE ANY CREDIT FOR WORK, YOUR SOCRE IS
5
UP TO YOUR UPMOST EFFORT AND WE WILL NOT BE HELD RESPONSIBLE FOR
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5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
AP Biology Review
UNIT I: CHEMISTRY OF LIFE
A. Elements
All life forms made up of matter
All matter made up ofelements
Elements
Substances that cannot be broken down into smaller substances
by chemical means
B. Essential Elements of Life
96% of the mass of all living things made up of 4 elements:
Oxygen(O)
Carbon(C)
Hydrogen(H)
Nitrogen(N)
Other elements (collectively 4% of biomass)
Calcium (Ca)
Phosphorus (P)
Potassium (K)
Sulfur (S)
Sodium (Na)
Chlorine (Cl)
Magnesium (Mg)
Trace elements
IRon (Fe)
Iodine (I)
Copper (Cu)
C. Subatomic Particles
Atom
Smallest unit of an element
Building blocks of physical world
Subatomic PArticles
Protons
Packed with neutrons in nucleus
Positively charged
Most atoms have same amount of protons as electrons, making them
electrically neutral
Neutrons
Packed with protons in nucleus
No charge
Isotopes
Same element with different amount of neutrons in nucleus
Vary in mass
STAR AP CRAM ACADEMY DOES NOT TAKE ANY CREDIT FOR WORK, YOUR SOCRE IS
5
UP TO YOUR UPMOST EFFORT AND WE WILL NOT BE HELD RESPONSIBLE FOR
PLAGARISM, AI USAGE, AND FRAUD ACCUSATIONS
,✨
5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
adioactive isotopesdecay spontaneously, giving off particles
R
and energy
Electrons
Negatively charged
Spin around nucleus
Very small; effectively massless
Electrons on an atom differ in their amounts of potential energy
Electron’s state of potential energy is called its energy level, orelectron
shell
Valence electronsare those in the outermost shell,orvalence shell
Chemical behavior of an atom is mostly determined by the distribution of
electrons in electron shells
Valence shell most important
Elements with full valence shells are chemicallyinert
Atoms with incomplete valence shells can share or transfer
valence electrons with certain other atoms
Atoms of different various elements differ in number of subatomic particles
Atomic number=#protons in nucleus
Mass Number= protons+neutrons
Average of all isotopes
Atomic mass+atom’s weighted average total mass
D. Compounds
Compoundoccurs as result of 2 or more individualelements combining in a fixed ratio
Different properties of individual elements
Formed by chemical reaction
Bonds that hold compounds together
Ionic bonds
nonmetal+metal
One or more electrons is transferred from one atom to another
One atom loses electrons (becomes positively charged) while the other
gains electrons (becomes negatively charged)
Results from attraction of two oppositely charged ions
STAR AP CRAM ACADEMY DOES NOT TAKE ANY CREDIT FOR WORK, YOUR SOCRE IS
5
UP TO YOUR UPMOST EFFORT AND WE WILL NOT BE HELD RESPONSIBLE FOR
PLAGARISM, AI USAGE, AND FRAUD ACCUSATIONS
,✨
5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
ationhas a positive charge
C
Anionhas a negative charge
Cation and anion form to create ionic bond
Covalent bonds
nonmetal+nonmetal
Moleculeconsists of 2 or more atoms held togetherby covalent bonds
Formed when electrons are shared between atoms
Innonpolar covalentbond, electrons are shared equally
Inpolar covalentbond, electrons are shared unequally
In asingle covalent bond, one pair of electrons isshared
Double covalent when 2 pairs are shared, etc.
Structural formulaused to represent atoms and bonding
Ex. H-H
Molecular formulaabbreviates structural formula
Ex. H2
lectronegativityis an atom’s attraction for theatoms in a
E
covalent bond
The more electronegative an atom, the more strongly it
pulls shared electrons toward itself
Hydrogen bonds
Hydrogen atom covalently bonds to one electronegative ato is also
attracted to another electronegative atom
In living cells, hydrogen bonds are usually oxygen or other nitrogen
atoms
Van der Waals Interactions
Weakest
If electrons are distributed asymmetrically in molecules or atoms, they
can result in “hot spots” of positive or negative charge
Attractions between molecules that are close together as a result of these
charges
How geckos climb
. Water: The Versatile Molecule
E
In water, electrons are not shared equally in the bonds between hydrogen and oxygen
Hydrogen atoms have a partial positive charge while oxygen atoms has a partial
negative charge
Water is polar
STAR AP CRAM ACADEMY DOES NOT TAKE ANY CREDIT FOR WORK, YOUR SOCRE IS
5
UP TO YOUR UPMOST EFFORT AND WE WILL NOT BE HELD RESPONSIBLE FOR
PLAGARISM, AI USAGE, AND FRAUD ACCUSATIONS
, ✨
5 STAR AP CRAM ACAD ✨ DUPLICATION NOT PERMITTED WITHOUT LISCENCE
Hydrogen bonds
Weak attractions that result of water’s polarity
Positive end of another polar molecule attracted to oxygen negative
charge, and vice versa with the hydrogen end
Hydrogen atom covalently bonded to one electronegative atom is also
attracted to another electronegative atom
Weak Individually, but strong on a larger scale
Lends watermany special properties
Cohesion
Tendency for water to stick to water
Important during transpiration
Water evaporates, pulls other water molecules with it,
pulling all the way down from leaves to roots
Adhesion
Tendency of water to stick to other substances
Cohesion + Adhesion =capillary action
Allows water to flow up roots/trunks/branches of trees in
thin vessels
Surface tension
Results from cohesion of water molecules
Ex. water striders can sit on top of water without sinking
High heat capacity
Heat CApacity=ability of a substance to resist temperature
changes
Keeps ocean temperatures stable
Allows organisms to keep constant body temperature, since most
life forms are mostly made up of water
Heat is absorbed when hydrogen bonds break, released when
hydrogen bonds form
High heat of vaporization
Heat a liquid must absorb for 1g to be converted to gas
STAR AP CRAM ACADEMY DOES NOT TAKE ANY CREDIT FOR WORK, YOUR SOCRE IS
5
UP TO YOUR UPMOST EFFORT AND WE WILL NOT BE HELD RESPONSIBLE FOR
PLAGARISM, AI USAGE, AND FRAUD ACCUSATIONS
