Standard 8.5.e
Students know how to determine
whether a solution is acidic, basic, or
neutral.
CA6
McDougal Littell Science
Standard 8.4.e
Students know the appearance, gen-
eral composition, relative position
and size, and motion of objects in
the solar system, including planets,
planetary satellites, comets, and
asteroids.
Standard 8.5.a
Students know reactant atoms and
molecules interact to form products
with different chemical properties.
What It Means to You
By studying the properties and orbits of planets, moons, and other
solar system objects, scientists have developed theories about how
the solar system formed. The most current theory explains the differ-
ence between the rocky inner planets and the gaseous giant outer
planets, as well as why planets and moons mostly orbit in the same
direction. (Chapters 12 and 13)
What It Means to You
After a chemical reaction, a new substance is formed. During a
chemical reaction, atoms change places with other atoms to form
other compounds. Because atoms are then arranged in a different
way, the new compounds have traits that often are not like those
of the original compounds. (Chapter 9)
Standard 8.5.b
Students know the idea of atoms
explains the conservation of matter: In
chemical reactions the number of
atoms stays the same no matter how
they are arranged, so their total mass
stays the same.
What It Means to You
Atoms are rearranged in chemical reactions. The number of atoms
does not change. The number of atoms present before a chemical
reaction is the same number present after a chemical reaction.
This is known as the law of the conservation of mass
(Chapter 9)
Standard 8.5.c
Students know chemical reactions
usually liberate heat or absorb heat.
What It Means to You
Some chemical reactions raise the temperature of their surround-
ings. Other chemical reactions decrease the temperature of their
surroundings. (Chapter 9)
Standard 8.5.d
Students know physical processes
include freezing and boiling, in which
a material changes form with no
chemical reaction.
What It Means to You
You have seen a physical change each time you have left a glass
of ice sit on a table. Eventually, ice melts and turns into water. Ice
and water are the same substance. You can easily turn water back
to ice simply by placing it in a freezer. When you boil water on a
stove to make soup or tea, however, it may seem as if some of
the water disappears into thin air. It really does not. It only has
become a gas and mixed with the air. (Chapter 6)
Standard 8.4.d
Students know that stars are the
source of light for all bright objects in
outer space and that the Moon and
planets shine by reflected sunlight,
not by their own light.
What It Means to You
Stars and planets appear as bright dots in the nighttime sky. Stars
produce their own light by fusing hydrogen into helium. Planets
and moons do not produce their own visible light. Planets and
moons, including our own Moon, are bright because they reflect
sunlight. (Chapters 12, 13, and 14)
Reactions
Standard 8.5: Chemical reactions are processes in which atoms are rearranged into different combinations
of molecules.
What It Means to You
Acids and bases are two types of solution. One way to tell the dif-
ference between an acid and a base is by using litmus paper. Acids
will turn blue litmus paper red. Bases turn red litmus paper blue. A
solution that is neutral is neither an acid or a base. (Chapter 10)
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