AP Biology Unit 1, AP Biology Unit 2
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1. Matter Anything that takes up space and has mass.
2. Element Substance that cannot be broken down to other sub-
stances through chemical reactions. Each has a symbol.
92 occurring in nature.
3. Compound Substance consisting of two or more different elements
combined in a fixed ratio.
*Characteristics different than those of its elements
4. CHON 4 elements essential to life
5. Trace Elements Required by an organism only in minute quantities.
6. Atom Smallest unit of matter that retains the properties of an
element. Composed of subatomic particles. Mostly empty
space.
7. Subatomic parti- Neutrons, protons, electrons. Make up atoms.
cles
8. Proton One unit of positive charge. Approximately one dalton.
Located in nucleus.
9. Electron One unit of negative charge. Located outside of nucleus.
, AP Biology Unit 1, AP Biology Unit 2
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10. Atomic Nucleus Dense core packed with protons and neutrons.
11. Neutrons Electrically neutral. Approximately one dalton.
12. 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
13. Mass Number Sum of the protons and the neutrons. An approximation
of the atomic mass.
14. Isotopes Same number of protons, but different number of neu-
trons and therefore different mass. Same element.
, AP Biology Unit 1, AP Biology Unit 2
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15. Radioactive Iso- One in which the nucleus decays spontaneously, giving
tope off particles and energy. Can decay to a different element.
Have useful applications.
16. Energy Capacity to cause change
17. Potential Energy Energy matter possesses because of its location or struc-
ture. Electrons have this based on distance from nucleus.
18. Electron Shells Where electrons are found, each with characteristic av-
erage distance and energy level. Electrons can change
these by absorbing or losing energy.
19. Valence Elec- Electrons in the outermost shell.
trons
, AP Biology Unit 1, AP Biology Unit 2
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20. Chemical Bonds The attraction that holds atoms together during an inter-
action.
21. Covalent Bond Sharing of a pair of valence electrons by two atoms.
22. Molecule Two or more atoms held together by covalent bonds.
23. Single Bond One pair of shared electrons.
24. Structural For- H--H. Notation which represents both atoms and bonding.
mula
25. Double Bond Sharing two pairs of valence electrons.
26. Valence Bonding capacity. Equal to the number of unpaired elec-
trons required to complete the outermost (valence) shell.
27. Electronegativity The attraction of a particular kind of atom for the electrons
of a covalent bond.
28. Nonpolar Cova- Covalent bond in which electrons are shared equally.
lent Bond
Study online at https://quizlet.com/_fij4p3
1. Matter Anything that takes up space and has mass.
2. Element Substance that cannot be broken down to other sub-
stances through chemical reactions. Each has a symbol.
92 occurring in nature.
3. Compound Substance consisting of two or more different elements
combined in a fixed ratio.
*Characteristics different than those of its elements
4. CHON 4 elements essential to life
5. Trace Elements Required by an organism only in minute quantities.
6. Atom Smallest unit of matter that retains the properties of an
element. Composed of subatomic particles. Mostly empty
space.
7. Subatomic parti- Neutrons, protons, electrons. Make up atoms.
cles
8. Proton One unit of positive charge. Approximately one dalton.
Located in nucleus.
9. Electron One unit of negative charge. Located outside of nucleus.
, AP Biology Unit 1, AP Biology Unit 2
Study online at https://quizlet.com/_fij4p3
10. Atomic Nucleus Dense core packed with protons and neutrons.
11. Neutrons Electrically neutral. Approximately one dalton.
12. 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
13. Mass Number Sum of the protons and the neutrons. An approximation
of the atomic mass.
14. Isotopes Same number of protons, but different number of neu-
trons and therefore different mass. Same element.
, AP Biology Unit 1, AP Biology Unit 2
Study online at https://quizlet.com/_fij4p3
15. Radioactive Iso- One in which the nucleus decays spontaneously, giving
tope off particles and energy. Can decay to a different element.
Have useful applications.
16. Energy Capacity to cause change
17. Potential Energy Energy matter possesses because of its location or struc-
ture. Electrons have this based on distance from nucleus.
18. Electron Shells Where electrons are found, each with characteristic av-
erage distance and energy level. Electrons can change
these by absorbing or losing energy.
19. Valence Elec- Electrons in the outermost shell.
trons
, AP Biology Unit 1, AP Biology Unit 2
Study online at https://quizlet.com/_fij4p3
20. Chemical Bonds The attraction that holds atoms together during an inter-
action.
21. Covalent Bond Sharing of a pair of valence electrons by two atoms.
22. Molecule Two or more atoms held together by covalent bonds.
23. Single Bond One pair of shared electrons.
24. Structural For- H--H. Notation which represents both atoms and bonding.
mula
25. Double Bond Sharing two pairs of valence electrons.
26. Valence Bonding capacity. Equal to the number of unpaired elec-
trons required to complete the outermost (valence) shell.
27. Electronegativity The attraction of a particular kind of atom for the electrons
of a covalent bond.
28. Nonpolar Cova- Covalent bond in which electrons are shared equally.
lent Bond
