Transcript Lesson 2a - Freeman Public Schools

PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
Basic
Chemistry
2
PART A
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Matter
 Biochemistry- the specialized area of chemistry
that deals with living organisms and life
processes
 Matter—anything that occupies space and has
mass (weight)
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Energy
 Energy—the ability to do work or put matter in
motion
 Kinetic- when energy is doing work, moving
objects
 Potential- when energy is inactive or stored
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Energy
 Forms of Energy
 Chemical- stored in bonds
 Electrical- results from movement of charged
particles
 Mechanical- energy directly involved in
moving matter
 Radiant- travels in waves
 X-ray
 Infrared
 Radio waves
 heat
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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)
 Others present in trace amounts
 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
 Indirectly related to the number of electrons
 Atomic mass number—sum of the protons and
neutrons
 Only nucleus has mass
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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
 When we are exposed to radiation it knocks
electrons out of their shell and may kill the cell
 Alpha radiation is the weakest
 Gamma radiation is the strongest
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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 or octet rule
 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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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
Figure 2.5b
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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
PLAY Ionic Bonds
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Ionic Bonds
Na
Cl
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
+
–
Na
Cl
Sodium ion (Na+)
Chloride ion (Cl–)
Sodium chloride (NaCl)
Figure 2.6
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Ionic Bonds
Na
Cl
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
Figure 2.6, step 1
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Ionic Bonds
Na
Cl
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
Figure 2.6, step 2
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Ionic Bonds
Na
Cl
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
+
–
Na
Cl
Sodium ion (Na+)
Chloride ion (Cl–)
Sodium chloride (NaCl)
Figure 2.6, step 3
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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
PLAY Covalent Bonds
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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
 Causes surface tension property of water and
allows water to change states easily
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Hydrogen Bonds
Figure 2.9
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Patterns of Chemical Reactions
 Synthesis reaction (A + BAB)
 Atoms or molecules combine
 Energy is absorbed for bond formation
 Decomposition reaction (ABA + 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 + CAC + 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
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