Embed Size (px)
Citation preview
End Show
Slide
1 of 40
Copyright Pearson Prentice Hall
Biology
End Show
Slide
2 of 40
Copyright Pearson Prentice Hall
2-1 The Nature of Matter
End Show
2-1 The Nature of Matter
Slide
3 of 40
Copyright Pearson Prentice Hall
Atoms
Atoms
The study of chemistry begins with the basic unit of
matter, the atom.
End Show
2-1 The Nature of Matter
Slide
4 of 40
Copyright Pearson Prentice Hall
Atoms
Placed side by side, 100 million atoms would make a
row only about 1 centimeter long.
Atoms contain subatomic particles that are even
smaller.
End Show
2-1 The Nature of Matter
Slide
5 of 40
Copyright Pearson Prentice Hall
Atoms
The subatomic particles that make up
atoms are
• protons
• neutrons
• electrons
End Show
2-1 The Nature of Matter
Slide
6 of 40
Copyright Pearson Prentice Hall
Atoms
The subatomic
particles in a helium
atom.
End Show
2-1 The Nature of Matter
Slide
7 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
Elements and Isotopes
A chemical element is a pure substance that
consists entirely of one type of atom.
• C stands for carbon.
• Na stands for sodium.
End Show
2-1 The Nature of Matter
Slide
8 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
The number of protons in an atom of an element is
the element's atomic number.
Commonly found in living organisms:
End Show
2-1 The Nature of Matter
Slide
9 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
Isotopes
Atoms of the same element that differ in the
number of neutrons they contain are known as
isotopes.
End Show
2-1 The Nature of Matter
Slide
10 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
Because they have the same number of
electrons, all isotopes of an element have
the same chemical properties.
End Show
2-1 The Nature of Matter
Slide
11 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
Isotopes of Carbon
6 electrons
6 protons
8 neutrons
End Show
2-1 The Nature of Matter
Slide
12 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
Radioactive Isotopes
Some isotopes are radioactive, meaning that their
nuclei are unstable and break down at a constant
rate over time
End Show
2-1 The Nature of Matter
Slide
13 of 40
Copyright Pearson Prentice Hall
Elements and Isotopes
Radioactive isotopes can be used:
• to determine the ages of rocks and fossils.
• to treat cancer.
• to kill bacteria that cause food to spoil.
• as labels or “tracers” to follow the movement of
substances within an organism.
End Show
2-1 The Nature of Matter
Slide
14 of 40
Copyright Pearson Prentice Hall
Chemical Compounds
Chemical Compounds
A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions.
End Show
2-1 The Nature of Matter
Slide
15 of 40
Copyright Pearson Prentice Hall
Chemical Compounds
Chemical Formula
Water
Table Salt
Hydrochloric Acid
Glucose
End Show
2-1 The Nature of Matter
Slide
16 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
Chemical Bonds
The atoms in compounds are held together by
chemical bonds.
The electrons that are available to form bonds are
called valence electrons.
End Show
2-1 The Nature of Matter
Slide
17 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
The main types of chemical bonds are:
• ionic bonds
• covalent bonds
End Show
2-1 The Nature of Matter
Slide
18 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
Ionic Bonds
An ionic bond is formed when one or more electrons are transferred from one atom to another.
These positively and negatively charged atoms are known as ions.
End Show
2-1 The Nature of Matter
Slide
19 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
Protons +17
Electrons - 18
Charge -1
Protons +11
Electrons - 11
Charge 0
Protons +11
Electrons - 10
Charge +1
Protons +17
Electrons - 17
Charge 0
Sodium ion (Cl-)Sodium atom (Na)
Sodium atom (Cl)Sodium ion (Na+)
End Show
2-1 The Nature of Matter
Slide
20 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
Covalent Bonds
Sometimes electrons are shared by atoms instead
of being transferred.
End Show
2-1 The Nature of Matter
Slide
21 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
A covalent bond forms when electrons are shared
between atoms.
• single covalent bond
• double bond
• triple bond
End Show
2-1 The Nature of Matter
Slide
22 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
The structure that results when atoms are joined
together by covalent bonds is called a molecule.
End Show
2-1 The Nature of Matter
Slide
23 of 40
Copyright Pearson Prentice Hall
Chemical Bonds
Van der Waals Forces
When molecules are close together, a slight
attraction can develop between the oppositely
charged regions of nearby molecules.
van der Waals forces
End Show
- or -
Continue to: Click to Launch:
Slide
24 of 40
Copyright Pearson Prentice Hall
2-1
End Show
Slide
25 of 40
Copyright Pearson Prentice Hall
2-1
The particles that move around the nucleus of
an atom are called
a. neutrons.
b. protons.
c. electrons.
d. isotopes.
End Show
Slide
26 of 40
Copyright Pearson Prentice Hall
2-1
The atomic number of a carbon atom is 6. How
many neutrons does the isotope carbon-14
have?
a. 6
b. 8
c. 12
d. 14
End Show
Slide
27 of 40
Copyright Pearson Prentice Hall
2-1
Which of the following statements about the three isotopes of carbon is true?
a. They are all radioactive.
b. They have different numbers of electrons.
c. They have the same chemical properties but differ in atomic mass.
d. They have the same number of protons and neutrons.
End Show
Slide
28 of 40
Copyright Pearson Prentice Hall
2-1
A chemical compound consists of
a. Electrons mixed with neutrons.
b. two or more elements combined in a definite proportion.
c. two or more protons combined in any proportion.
d. at least three elements combined by ionic or covalent bonds.
End Show
Slide
29 of 40
Copyright Pearson Prentice Hall
2-1
Van der Waals forces are the result of
a. unequal sharing of electrons.
b. ionic bonds.
c. the bonding of different isotopes.
d. the chemical combination of sodium and
chlorine.
END OF SECTION
End Show
Slide
31 of 40
End Show
Slide
32 of 40
Copyright Pearson Prentice Hall
2-2 Properties of Water
End Show
Slide
33 of 40
A water molecule is polar
because there is an uneven
distribution of electrons
between the oxygen and
hydrogen atoms.
Copyright Pearson Prentice Hall
The Water Molecule
End Show
Slide
34 of 40
Copyright Pearson Prentice Hall
The Water Molecule
Water Molecule
End Show
Slide
35 of 40
Copyright Pearson Prentice Hall
The Water Molecule
Hydrogen Bonds
Because of their partial positive and
negative charges, polar molecules can
attract each other.
End Show
Slide
36 of 40
Copyright Pearson Prentice Hall
The Water Molecule
Cohesion is an attraction
between molecules of the
same substance.
Because of hydrogen
bonding, water is
extremely
cohesive.
End Show
Slide
37 of 40
Copyright Pearson Prentice Hall
The Water Molecule
Adhesion is an attraction
between molecules of
different substances.
End Show
Slide
38 of 40
Copyright Pearson Prentice Hall
Solutions and Suspensions
Solutions and Suspensions
A mixture is a material composed of
two or more elements or compounds that
are physically mixed but not chemically
combined.
End Show
Slide
39 of 40
Copyright Pearson Prentice Hall
Solutions and Suspensions
Two types of mixtures can
be made with water
• solutions
• suspensions
End Show
Slide
40 of 40
Copyright Pearson Prentice Hall
Solutions and Suspensions
Solutions
All the components of a solution are
evenly distributed throughout the
solution.
solute—the substance that is
dissolved.
solvent—the substance in which
the solute dissolves.
End Show
Slide
41 of 40
Copyright Pearson Prentice Hall
Solutions and Suspensions
When a crystal of table salt is
placed in warm water, sodium and
chloride ions are attracted to the
polar water molecules.
Na+
Na+
Cl -Cl -
Wate
r
Wate
r
End Show
Slide
42 of 40
Copyright Pearson Prentice Hall
Solutions and Suspensions
Suspensions
Some materials do not dissolve when
placed in water but separate into pieces
so small that they do not settle out easily.
End Show
Slide
43 of 40
Copyright Pearson Prentice Hall
Acids, Bases, and pH
Acids, Bases, and pH
A water molecule is neutral, but can
react to form hydrogen and hydroxide
ions.
H2O H+ + OH-
End Show
Slide
44 of 40
Copyright Pearson Prentice Hall
Acids, Bases, and pH
The pH scale
Chemists devised a measurement
system called the pH scale to indicate the
concentration of H+ ions in solution.
The pH scale ranges from 0 to 14.
End Show
Slide
45 of 40
Copyright Pearson Prentice Hall
Acids, Bases, and pH
At a pH of 7,
the
concentration
of H+ ions and
OH- ions is
equal.
The pH Scale
Human blood
Milk
Sea water
Normal rainfall
Pure water
End Show
Slide
46 of 40
Copyright Pearson Prentice Hall
Acids, Bases, and pH
AcidsAn acid is any compound that forms hydrogen
(H+) ions in solution.
End Show
Slide
47 of 40
Copyright Pearson Prentice Hall
Acids, Bases, and pH
Bases
A base is a compound that produces hydroxide
ions (OH-) ions in a solution.
End Show
Slide
48 of 40
Copyright Pearson Prentice Hall
Acids, Bases, and pH
Buffers
The pH of the fluids within most cells in the
human body must generally be kept between
6.5 and 7.5.
Controlling pH is important for maintaining
homeostasis.
End Show
Slide
49 of 40
Copyright Pearson Prentice Hall
2-2
End Show
Slide
50 of 40
Copyright Pearson Prentice Hall
2-2 A molecule in which the
charges are unevenly
distributed is called a
• polar molecule.
• cohesive molecule.
• hydrogen molecule.
• covalent molecule.
End Show
Slide
51 of 40
Copyright Pearson Prentice Hall
2-2 A dissolved substance is
called a
• solvent.
• solution.
• solute.
• Suspension.
End Show
Slide
52 of 40
Copyright Pearson Prentice Hall
2-2 A compound that produces
hydroxide ions in solution
is called a(an)
• base.
• buffer.
• acid.
• salt.
End Show
Slide
53 of 40
Copyright Pearson Prentice Hall
2-2Hydrogen bonds between
water molecules result from
• adhesion between water molecules.
• magnetic attractions between water molecules.
• uneven electron distribution in each water molecule.
• ionic bonds in the water molecule.
End Show
Slide
54 of 40
Copyright Pearson Prentice Hall
2-2
On a pH scale, a value of 2
means that the solution has
• equal concentrations of H+ and OH- ions.
• the same concentration of H+ ions as pure
water.
• higher concentration of H+ than in pure water.
• lower concentration of H+ than in pure water.
END OF SECTION
