AP Biology Unit 1, AP Biology Unit 2
Questions and Answers
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.
Questions and Answers
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.
