Transcript Chapter 2 Chemistry comes alive

Section 2a
Levels
Chemical
Cells
Tissue
Organ
Organ
system
• Organism
•
•
•
•
•
Today we are
working on…
Matter
• The “stuff” of the universe
• Anything that has mass and takes up
space
• States of matter
–Solid – has definite shape and volume
–Liquid – has definite volume,
changeable shape
–Gas – has changeable shape and
volume
Energy
• The capacity to do work (put
matter into motion)
• Types of energy
–Kinetic – energy in action
–Potential – energy of position;
stored (inactive) energy
Forms of Energy
• Chemical – stored in the bonds of
chemical substances
• Electrical – results from the
movement of charged particles
• Mechanical – directly involved in
moving matter
• Radiant or electromagnetic – energy
traveling in waves (i.e., visible light,
ultraviolet light, and
X rays)
Energy Form Conversions
• Energy is easily converted from one
form to another
• During conversion, some energy is
“lost” as heat
• Energy is never created or
destroyed
Composition of Matter
• Elements are the fundamental units
of matter
• Elements – unique substances that
cannot be broken down by ordinary
chemical means
Properties of Elements
• Each element has unique physical
and chemical properties
–Physical properties – those
detected with our senses
–Chemical properties – pertain to
the way atoms interact with one
another
Major Elements of the Human Body
• There are about 120 known elements
– 92 occur in nature – the rest are
man-made
• 96% of the body is made from four
elements - Know these –
•
•
•
•
Oxygen (O)
Carbon (C)
Hydrogen (H)
Nitrogen (N)
Lesser Elements of the Human
Body
• Lesser elements make up 3.9% of
the body and include:
–Calcium (Ca), phosphorus (P),
potassium (K), sulfur (S), sodium
(Na), chlorine (Cl), magnesium
(Mg), iodine (I), and iron (Fe)
Trace Elements of the Human
Body
• Trace elements make up less than
0.01% of the body
–They are required in minute
amounts, and are found as part of
enzymes
Composition of Matter
• Each Element is composed of Atoms
• Atoms = more or less identical
building blocks for each element
• Atomic symbol = one or two letter
chemical shorthand for each
element
Carbon C
Nitrogen N
Oxygen O
Calcium Ca
Hydrogen H Sodium Na
Atomic Structure
• The nucleus consists of neutrons and
protons
–Neutrons – have no charge and a
mass of one atomic mass unit (amu)
–Protons – have a positive charge and
a mass of
1 amu
Atomic Structure
• Electrons are found orbiting the
nucleus
–Electrons – have a negative charge
and 1/2000 the mass of a proton (0
amu)
Models of the Atom
• Nucleus
–Prontons (p+)
–Neutrons (n0)
• Outside of
nucleus
–Electrons (e-)
Figure 2.1
Models of the Atom
• Planetary
Model –
electrons
move
around the
nucleus in
fixed,
circular
orbits
Figure 2.1
Models of the Atom
• Orbital
Model –
regions
around the
nucleus in
which
electrons
are most
likely to be
found
Figure 2.1
Identification of Elements
• Atomic number –
–equal to the number of protons
that the atoms contain
• Mass number –
–equal to the mass of the protons
and neutrons – sum of the protons
and neutrons
Identification of Elements
• Atomic weight –
–average of the mass numbers of
all isotopes
–Close to mass number of most
abundant isotope
–Atomic weight reflects natural
isotope variation
Isotopes
• Isotope – atoms with same number of
protons but a different number of
neutrons
• Radioisotopes – atoms that undergo
spontaneous decay called
radioactivity
Radioactivity
• Rodioisotope –
–Heavy isotope
–Tends to be unstable
–Decomposes to more stable
isotope
• Radioactivity
–Process of spontaneous atomic
Identification of Elements
Figure 2.2
Identification of Elements
Isotopes of Hydrogen
Figure 2.3
Molecules and Compounds
• Molecule – two or more atoms held
together by chemical covalent bonds
• Compound – two or more different
kinds of atoms chemically bonded
together in ionic bonds
• Next time we will talk how these are
chemically bonded
Mixtures and Solutions
• Mixtures – two or more components
physically intermixed (not
chemically bonded)
• 3 basic types
–Solutions
–Colloids
–Suspensions
Solutions
• Solutions – homogeneous mixtures
of components
–Solvent – substance present in
greatest amount
–Solute – substance(s) present in
smaller amounts
• May be gases, liquids, or solids
Solutions
• Water is the body’s chief solvent
• Most solutions in the body are true
solutions containing gases, liquids,
or solids dissolved in water
–True solutions are usually
transparent
Concentration of Solutions
• True solutions are described in
terms of their concentration
(percent or molarity)
• Percent, or parts per 100 parts
• Molarity, or moles per liter (M)
Concentration of Solutions
• To make a one-molar solution of
glucose – weigh out 1 mole of
glucose and add enough water to
make 1 liter of solution
• A mole of an element or compound
is equal to its atomic or molecular
weight (sum of atomic weights) in
grams
• To find molecular weight of glucose
C6 H12 O6
– Glucose has 6 carbon, 12 hydrogen, & 6
oxygen atoms
• To compute molecular weight of glucose,
look up the atomic weight of carbon,
hydrogen and oxygen on a periodic table.
• Molecular weight of glucose is 180.156
Atom
# of atoms
X
Atomic
weight
=
Atomic
weight
C
6
X
12.033
=
72066
H
12
X
1.008
=
12.096
O
6
X
15.999
=
95.994
180.456
Avogadro’s Number
• One mole of any substance always
contains exactly the same number of
solute particles
6.02 X 1023
• So whether you weigh out 1 mole of
glucose (180g) or water (18g) or
methane (16g) or any other substance
you will always have 6.02x1023
molecules of that substance
Colloids and Suspensions
• Colloids, or emulsions, are
heterogeneous mixtures whose
solutes do not settle out
• Suspensions are heterogeneous
mixtures with visible solutes that
tend to settle out
Mixtures Compared with Compounds
• No chemical bonding takes place in
mixtures
• Most mixtures can be separated by
physical means
• Mixtures can be heterogeneous or
homogeneous
• Compounds cannot be separated by
physical means
• All compounds are homogeneous
Quiz 1a over these lecture notes