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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

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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