Ch. 2: The Chemical Context of Life
2.1
Matter consists of chemical elements in pure
form and in combinations called compounds.
Ch. 2: The Chemical Context of Life
2.2
An element’s properties depend on the
structure of its atoms.
Ch. 2: The Chemical Context of Life
2.3
The formation and function of molecules
depend on chemical bonding between atoms.
Ch. 2: The Chemical Context of Life
2.4
Chemical reactions make and break chemical
bonds.
Concept Check
2.1
(1)
Explain why table salt is a compound, while the oxygen
we breathe is not. What is the nitrogen we breathe?
(2)
What four chemical elements are most abundant in the
food you ate yesterday? Which elements, when added
to these four, bring the percentage of body elements
to over 99?
Concept Check
2.2
(1)
A nitrogen atom has 7 protons, and the most common
isotope of nitrogen has 7 neutrons. A radioactive
isotope of nitrogen has 8 neutrons. What is the
atomic number and mass number of this radioactive
nitrogen?
(2)
Look at figure 2.8, and determine the atomic number
of magnesium. How many protons and electrons does
it have? How many electron shells? How many valance
electrons are in the valance shell?
Concept Check
(1)
2.3
Why does the following structure fail to make
sense?
H–C=C–H
(2) Explain what holds together the atoms in
a crystal of magnesium chloride (MgCl2).
What holds the atoms of a water
molecule together?
Concept Check
2.4
(1)
Refer to the balanced chemical equation found on the
bottom left-hand side of page 44. How are the atoms
bonded together? Do you think energy goes into the
arrow or out from the arrow?
(2)
Which occurs faster at equilibrium, the formation of
products from reactants, or reactants from products?