PowerPoint Presentation - Nerve activates contraction · PDF file ·...
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PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
PART A2
Basic
Chemistry
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Matter and Energy
Matter—anything that occupies space and has
mass (weight)
Energy—the ability to do work
Chemical
Electrical
Mechanical
Radiant
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Composition of Matter
Elements—fundamental units of matter
96% of the body is made from four elements
Carbon (C)
Oxygen (O)
Hydrogen (H)
Nitrogen (N)
Atoms—building blocks of elements
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Atomic Structure
Nucleus
Protons (p+)
Neutrons (n0)
Outside of nucleus
Electrons (e-)
Figure 2.1
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Atomic Structure of Smallest Atoms
Figure 2.2
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Identifying Elements
Atomic number—equal to the number of protons
that the atom contains
Atomic mass number—sum of the protons and
neutrons
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Isotopes and Atomic Weight
Isotopes
Have the same number of protons
Vary in number of neutrons
Figure 2.3
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Isotopes and Atomic Weight
Atomic weight
Close to mass number of most abundant
isotope
Atomic weight reflects natural isotope
variation
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Radioactivity
Radioisotope
Heavy isotope
Tends to be unstable
Decomposes to more stable isotope
Radioactivity—process of spontaneous atomic
decay
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Molecules and Compounds
Molecule—two or more like atoms combined
chemically
Compound—two or more different atoms
combined chemically
Figure 2.4
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Chemical Reactions
Atoms are united by chemical bonds
Atoms dissociate from other atoms when
chemical bonds are broken
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Electrons and Bonding
Electrons occupy energy levels called electron
shells
Electrons closest to the nucleus are most
strongly attracted
Each shell has distinct properties
The number of electrons has an upper limit
Shells closest to the nucleus fill first
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Electrons and Bonding
Bonding involves interactions between electrons
in the outer shell (valence shell)
Full valence shells do not form bonds
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Inert Elements
Atoms are stable (inert) when the outermost shell
is complete
How to fill the atom’s shells
Shell 1 can hold a maximum of 2 electrons
Shell 2 can hold a maximum of 8 electrons
Shell 3 can hold a maximum of 18 electrons
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Inert Elements
Atoms will gain, lose, or share electrons to
complete their outermost orbitals and reach a
stable state
Rule of eights
Atoms are considered stable when their
outermost orbital has 8 electrons
The exception to this rule of eights is Shell 1,
which can only hold 2 electrons
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Inert Elements
Figure 2.5a
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Figure 2.5b
Reactive Elements
Valence shells are not full and are unstable
Tend to gain, lose, or share electrons
Allow for bond formation, which produces
stable valence
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Chemical Bonds
Ionic bonds
Form when electrons are completely
transferred from one atom to another
Ions
Charged particles
Anions are negative
Cations are positive
Either donate or accept electrons
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Ionic Bonds
Figure 2.6
+ –
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
Sodium ion (Na+) Chloride ion (Cl–)
Sodium chloride (NaCl)
ClNaClNa
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Ionic Bonds
Figure 2.6, step 1
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
ClNa
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Ionic Bonds
Figure 2.6, step 2
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
ClNa
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Ionic Bonds
Figure 2.6, step 3
+ –
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
Sodium ion (Na+) Chloride ion (Cl–)
Sodium chloride (NaCl)
ClNaClNa
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Chemical Bonds
Covalent bonds
Atoms become stable through shared
electrons
Single covalent bonds share one pair of
electrons
Double covalent bonds share two pairs of
electrons
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Examples of Covalent Bonds
Figure 2.7a
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Examples of Covalent Bonds
Figure 2.7b
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Examples of Covalent Bonds
Figure 2.7c
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Polarity
Covalently bonded
molecules
Some are non-polar
Electrically
neutral as a
molecule
Some are polar
Have a positive
and negative
side
Figure 2.8
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Chemical Bonds
Hydrogen bonds
Weak chemical bonds
Hydrogen is attracted to the negative portion
of polar molecule
Provides attraction between molecules
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Hydrogen Bonds
Figure 2.9
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Patterns of Chemical Reactions
Synthesis reaction (A + BAB)
Atoms or molecules combine
Energy is absorbed for bond formation
Decomposition reaction (ABA + B)
Molecule is broken down
Chemical energy is released
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Synthesis and Decomposition Reactions
Figure 2.10a
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Synthesis and Decomposition Reactions
Figure 2.10b
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Patterns of Chemical Reactions
Exchange reaction (AB + CAC + B)
Involves both synthesis and decomposition
reactions
Switch is made between molecule parts and
different molecules are made
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Patterns of Chemical Reactions
Figure 2.10c