AP Biology Unit 1, AP Biology Unit 2 - Unit
one: The Chemistry of Life Chapter 2: The
Chemical Context of life
Matter
Anything that takes up space and has mass.
Element
Substance that cannot be broken down to other substances through
chemical reactions. Each has a symbol. 92 occurring in nature.
Compound
Substance consisting of two or more different elements combined in a fixed
ratio.
*Characteristics different than those of its elements
CHON
4 elements essential to life
Trace Elements
Required by an organism only in minute quantities.
Atom
Smallest unit of matter that retains the properties of an element. Composed
of subatomic particles. Mostly empty space.
Subatomic particles
Neutrons, protons, electrons. Make up atoms.
Proton
One unit of positive charge. Approximately one dalton. Located in nucleus.
Electron
One unit of negative charge. Located outside of nucleus.
,Atomic Nucleus
Dense core packed with protons and neutrons.
Neutrons
Electrically neutral. Approximately one dalton.
Atomic Number
The number of protons (which is unique to that element) and written as a
subscript to left of element symbol. Also tells us number of electrons since
P=E if atom is neutral
Mass Number
Sum of the protons and the neutrons. An approximation of the atomic
mass.
Isotopes
Same number of protons, but different number of neutrons and therefore
different mass. Same element.
Radioactive Isotope
One in which the nucleus decays spontaneously, giving off particles and
energy. Can decay to a different element. Have useful applications.
Energy
Capacity to cause change
Potential Energy
Energy matter possesses because of its location or structure. Electrons
have this based on distance from nucleus.
Electron Shells
Where electrons are found, each with characteristic average distance and
energy level. Electrons can change these by absorbing or losing energy.
Valence Electrons
Electrons in the outermost shell.
, Chemical Bonds
The attraction that holds atoms together during an interaction.
Covalent Bond
Sharing of a pair of valence electrons by two atoms.
Molecule
Two or more atoms held together by covalent bonds.
Single Bond
One pair of shared electrons.
Structural Formula
H--H. Notation which represents both atoms and bonding.
Double Bond
Sharing two pairs of valence electrons.
Valence
Bonding capacity. Equal to the number of unpaired electrons required to
complete the outermost (valence) shell.
Electronegativity
The attraction of a particular kind of atom for the electrons of a covalent
bond.
Nonpolar Covalent Bond
Covalent bond in which electrons are shared equally.
Polar Covalent Bond
Where one atom is bonded to a more electronegative atom and the
electrons of the bond are not shared equally.
Ionic Bonds
one: The Chemistry of Life Chapter 2: The
Chemical Context of life
Matter
Anything that takes up space and has mass.
Element
Substance that cannot be broken down to other substances through
chemical reactions. Each has a symbol. 92 occurring in nature.
Compound
Substance consisting of two or more different elements combined in a fixed
ratio.
*Characteristics different than those of its elements
CHON
4 elements essential to life
Trace Elements
Required by an organism only in minute quantities.
Atom
Smallest unit of matter that retains the properties of an element. Composed
of subatomic particles. Mostly empty space.
Subatomic particles
Neutrons, protons, electrons. Make up atoms.
Proton
One unit of positive charge. Approximately one dalton. Located in nucleus.
Electron
One unit of negative charge. Located outside of nucleus.
,Atomic Nucleus
Dense core packed with protons and neutrons.
Neutrons
Electrically neutral. Approximately one dalton.
Atomic Number
The number of protons (which is unique to that element) and written as a
subscript to left of element symbol. Also tells us number of electrons since
P=E if atom is neutral
Mass Number
Sum of the protons and the neutrons. An approximation of the atomic
mass.
Isotopes
Same number of protons, but different number of neutrons and therefore
different mass. Same element.
Radioactive Isotope
One in which the nucleus decays spontaneously, giving off particles and
energy. Can decay to a different element. Have useful applications.
Energy
Capacity to cause change
Potential Energy
Energy matter possesses because of its location or structure. Electrons
have this based on distance from nucleus.
Electron Shells
Where electrons are found, each with characteristic average distance and
energy level. Electrons can change these by absorbing or losing energy.
Valence Electrons
Electrons in the outermost shell.
, Chemical Bonds
The attraction that holds atoms together during an interaction.
Covalent Bond
Sharing of a pair of valence electrons by two atoms.
Molecule
Two or more atoms held together by covalent bonds.
Single Bond
One pair of shared electrons.
Structural Formula
H--H. Notation which represents both atoms and bonding.
Double Bond
Sharing two pairs of valence electrons.
Valence
Bonding capacity. Equal to the number of unpaired electrons required to
complete the outermost (valence) shell.
Electronegativity
The attraction of a particular kind of atom for the electrons of a covalent
bond.
Nonpolar Covalent Bond
Covalent bond in which electrons are shared equally.
Polar Covalent Bond
Where one atom is bonded to a more electronegative atom and the
electrons of the bond are not shared equally.
Ionic Bonds
