AP Biology I
Pennsbury High School
Chemical Context for Biology
Answers
Chemistry Review Packet
1. Organisms are made of the same chemical elements as nonliving things. One
important difference is the complexity of organization in living things when
compared to nonliving. The atoms of living things are organized into small molecules
like sugars, amino acids, fatty acids, and nucleic acids. These small molecules are
linked together to form macromolecules, and the macromolecules are organized into
larger structures called macromolecular assemblies. Examples of macromolecular
assemblies include ribosomes, membranes and chromatin.
2. The six most abundant elements (in decreasing order of abundance) are
Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, Phosphorus.
Mnemonic →
Trace elements are those required by organisms in only minute quantities (less than
0.01% of human body weight). These are B, Cr, Co, Cu, F, I, Fe, Mn, Mo, Se, Si, Sn,
V, Zn. (Note: It is not necessary to memorize the names or symbols of these trace
elements.)
Many trace elements are enzyme cofactors (e.g, Cu, Zn, Mn, Mg, Mo). Other
functions include serving as electrolytes (nerve function), in osmotic balance, and in
acid-base balance. Check out Table 41.2 Mineral requirements of Humans on page
852 of Campbell (I love that book!). Don’t memorize the table, just look at it. It’s
cool!
3. Atoms have a nucleus at the center which is surrounded by an electron cloud. The
electron cloud is organized into a series of seven progressively larger concentric
shells (somewhat like an onion).
The ratio of the diameter of the electron cloud to the diameter of the nucleus is
Electron cloud
Nucleus
10-8 cm
----------10-13 cm
=
105
Thus the diameter of the electron cloud is 100,000 times larger than the diameter of
the nucleus.
If the nucleus were as large as a baseball (with a radius of about 3.5.cm), the radius of
the electron cloud would be ~2 miles.
AP Biology I
Pennsbury High School
Chemical Context for Biology
4.
Element
Protons
Neutrons
Electrons
Oxygen
Carbon
Hydrogen
Nitrogen
Phosphorus
Sulfur
Calcium
Potassium
8
6
1
7
15
16
20
19
8
6
0
7
16
16
20
20
8
6
1
7
15
16
20
19
5
12
6
Isotope
14
N
15
N
31
P
32
P
32
S
35
S
13
C
Atomic
Number
7
7
15
15
16
16
6
Mass
Number
14
15
31
32
32
35
14
C
6
# of
Protons
7
7
15
15
16
16
C
# of
Neutrons
7
8
16
17
16
19
# of
Electrons
7
7
15
15
16
16
6.
Element
Oxygen (O)
Carbon (C)
Hydrogen (H)
Nitrogen (N)
Electron Configuration
1s 2s 2p (Atoms form 2 bonds)
1s22s22p2 (Atoms form 4 bonds)
1s1
(Atoms form 1 bond)
1s22s22p3 (Atoms form 3 bonds)
2
2
4
7.
Element
Sulfur (S)
Sodium (Na)
Chlorine (Cl)
Potassium (K)
Neon (Ne)
Electron Configuration
1s22s22p63s23p4
1s22s22p63s1
1s22s22p63s23p5
1s22s22p63s23p64s1
1s22s22p6
Valence Electrons
3s 3p4 (6 valence electrons)
3s1
(1 valence electron)
2
5
3s 3p (7 valence electrons)
4s1
(1 valence electron)
2
6
2s 2p (8 valence electrons)
2
AP Biology I
Pennsbury High School
Chemical Context for Biology
8.
Group (Family)
# of Valence Electrons
Halogens (Group 17 or VIIA)
Oxygen Family (Group 16 or VIA)
Nitrogen Family (Group 15 or VA)
Carbon Family (Group 14 or IVA)
7
6
5
4
Elements with the same number of valence electrons have similar chemical behavior.
9.
Bonding
2. Bonds between O and N atoms are polar covalent.
Bonds between Ca and F atoms are ionic
Bonds between Li and Cl atoms are ionic
Bonds between O and O atoms are nonpolar covalent
3. Na1+ and Ne have the same 2s22p6 valence shell electron configuration and both are
chemically very stable. Cl1- and Ar have the same 3s23p6 valence shell electron
configuration and both are chemically very stable.
See review packet and pretest for answers to the rest of 3 and #4.
Chapter 2 in Campbell, pp. 32-46 also reviews the chemistry that is important for the
class.