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Transcript
Lecture PowerPoint to accompany
Inquiry into Life
Twelfth Edition
Sylvia S. Mader
Chapter 2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
2.1 Basic Chemistry
Matter is anything that takes up space and
has weight.
2.1 Basic Chemistry
Matter is anything that takes up space and
has mass.
All matter, living or nonliving, is made up of
elements.
2.1 Basic Chemistry
Elements are substances that cannot be
broken down to simpler substances with
different properties.
Elements that make up the
Earth’s crust and its organisms.
Elements that make up 95%
of living organisms (by weight)
–C
Carbon
Elements that make up 95%
of living organisms (by weight)
–C
–H
Carbon
Hydrogen
Elements that make up 95%
of living organisms (by weight)
–C
–H
–N
Carbon
Hydrogen
Nitrogen
Elements that make up 95%
of living organisms (by weight)
–C
–H
–N
–O
Carbon
Hydrogen
Nitrogen
Oxygen
Elements that make up 95%
of living organisms (by weight)
–C
–H
–N
–O
–P
Carbon
Hydrogen
Nitrogen
Oxygen
Phosphorus
Elements that make up 95%
of living organisms (by weight)
–C
–H
–N
–O
–P
–S
Carbon
Hydrogen
Nitrogen
Oxygen
Phosphorus
Sulfur
Atomic Structure
• Atom: The smallest part of an element
that displays the properties of the element.
• Atom: The smallest part of an element
that displays the properties of the element.
• Atoms are made up of subatomic particles.
Subatomic Particles
• Protons (positively charged)
Subatomic Particles
• Protons (positively charged)
• Neutrons (uncharged)
Subatomic Particles
• Protons (positively charged)
• Neutrons (uncharged)
• Electrons (negatively charged)
Helium
Atomic Symbol
Atomic
Mass
12
Atomic
Number
6
C
Carbon
Atomic Symbol
Atomic Mass =
Number of Protons +
Number of Neutrons
Atomic Number = The Number of Protons
in the Nucleus
The Periodic Table
Isotopes
12
C
6
13
C
6
14
C*
6
*radioactive
Atoms of the same element
with a differing numbers of
neutrons
Radiation
• As radioactive isotopes decay, energy is
released in the form of subatomic particles
(radiation).
Some Uses of Low Levels of
Radiation
Some Uses of High Levels of
Radiation
Electrons
Electrons
• If an atom is electrically neutral, the
number of protons (positively charged) is
equal to the number of electrons
(negatively charged).
Energy Levels (electron shells)
Energy Levels (electron shells)
• The first shell (closest to the nucleus) can
contain two electrons
Energy Levels (electron shells)
• The first shell (closest to the nucleus) can
contain two electrons
• Each additional shell can contain eight
electrons
Energy Levels (electron shells)
• The first shell (closest to the nucleus) can
contain two electrons
• Each additional shell can contain eight
electrons
• Each lower shell is filled with electrons
before the next higher level contains any
electrons.
Periodic Table (Revisited)
Vertical columns indicate
number of electrons
in outermost shell
Horizontal
periods
indicate
total
number
of electron
shells
1
I
VIII
1
2
H
1.008
3
2
Li
He
II
III
IV
V
VI
VII
4
5
6
7
8
9
4.003
10
Be
B
C
N
O
F
Ne
6.941 9.012 10.81 12.01 14.01 16.00 19.00 20.18
11
12
13
14
15
16
17
18
3
Na Mg Al
Si
P
S
Cl Ar
22.99 24.31 26.98 28.09 30.97 32.07 35.45 39.95
19
20
21
22
23
24
25
26
4
K
Ca Ga Ge As Se Br Kr
39.10 40.08 69.72 72.59 74.92 78.96 79.90 83.60
Electrons
• Atoms can give up, accept, or share
electrons to have eight electrons in the
outer shell.
2.2 Elements and Compounds
2.2 Elements and Compounds
• Molecules form when two or more
atoms bond together (example: O2)
2.2 Elements and Compounds
• Molecules form when two or more atoms
bond together (example: O2)
• Compounds form when two or more
different elements bond together
(example: H2O)
2.2 Elements and Compounds
• Molecules form when two or more atoms
bond together (example: O2)
• Compounds form when two or more
different elements bond together (H2O)
• When a chemical reaction occurs, energy
may be given off or absorbed.
Ionic Bonding
• Ions are charged particles that form when
electrons are transferred from one atom to
another.
Ionic Bonding
• Ions are charged particles that form when
electrons are transferred from one atom to
another.
• Ionic compounds are held together by an
attraction between oppositely charged ions
called an ionic bond.
Ionic Bonding
Covalent Bonding
• In covalent bonds, atoms share electrons
allowing each atom to have a completed
outer shell.
Covalent Bonding
• A covalent bond
• A double covalent
bond
Shape of Molecules
Nonpolar covalent bonds
• If the sharing between
two atoms is fairly
equal, the covalent
bond is described as
nonpolar.
Polar Covalent Bonds
If the sharing between two atoms is unequal,
the covalent bond is described as polar.
Hydrogen Bonding
• A hydrogen bond
occurs between a
slightly positive
hydrogen atom of one
molecule and a
slightly negative atom
of another molecule,
or between atoms of
the same molecule.