Chapter #2 Lecture pp 12-29 Science, Atoms, Elements, &
Subatomic Particles Lecture Presentations for Integrated Biology
and Skills for Success in Science Banks, Montoya, Johns, &
Eveslage
Slide 2
Guiding Principles for the Course Looking at seemingly simple
things deeply Conceptual understanding Practical Applications
Contextualized
Slide 3
Chapter #2 Learning Objectives By the end of the lecture today,
students will be able to: List and define the typical stages in the
scientific method. Compare and contrast inductive versus deductive
reasoning. Compare and contrast mass versus weight as scientific
values Determine the mass of an atom when given the subatomic
particles. Define and describe chemistry terms such as element,
subatomic particle, proton, neutron, electron, atomic number and
atomic mass. Define isotopes and describe differences between
isotopes of an element. List the most abundant elements found in
the human body. Distinguish the role of valence electrons in
chemical reactions Identify and describe any general trends that
can be observed in the periodic table of elements including but not
limited to atomic mass, ionization energies, and electronegativity
values.
Slide 4
Scientific Method The Scientific Method involves a series of
steps that are used to investigate a natural occurrence It is
important to develop a deep understanding of this approach to
science as it is a universal way of looking at problems,
situations, and phenomena in nature Please become familiar with the
flowchart presented here and in your text
Slide 5
Deductive vs. Inductive Logic It is very important to define
the differences between the two major types of logic that will be
used to drive the scientific method in your future observations of
nature Deductive logic starts with a statement believed to be true
and then goes on to predict what facts would also have to be true
to be compatible with that statement In contrast, inductive logic
involves taking observations of facts and creating a new theory
that is compatible with those observations of facts
Slide 6
Control vs. Comparative Experiments There are two main types of
experiments used in science: The Controlled Experiment and The
Comparative Experiment The purpose of a controlled science
experiment is to find out what happens to something if you change
something else while you keep all other things unchanged In a
controlled experiment you can test only one independent variable
This means that you can change only one condition in your
experiment The purpose of a comparative experiment is to compare
the effect of two or more different things on something In a
comparative experiment you can test the effect of a few independent
variables but not in the same experimental group where also only
one independent variable is allowed as in the case of a controlled
experiment
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Slide 8
What is Biochemistry?? Life is all about the multitude of
biochemical reactions that take place all day every day Each part
of every living organism is biochemically connected Biochemistry is
defined as the study of life on a molecular level Biochemistry
covers the biochemical bonds linking atoms to form simple molecular
structures and larger structures like DNA, which holds genetic
information which flows into RNA and eventually proteins
Biochemistry is all about discovering new biochemical structures
and determining their functions and interactions with other
molecules Biochemistry deals with complex molecular machines,
metabolic pathways, and biochemical communications within and
in-between organisms
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Slide 10
The Chemical Elements Element - simplest form of matter to have
unique chemical properties Atomic number of an element - number of
protons in its nucleus periodic table elements arranged by atomic
number elements represented by one- or two letter symbols 24
elements have biological role 6 elements = 98.5% of body weight
oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus trace
elements in minute amounts
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Atomic Structure Nucleus - center of atom protons: single +
charge, mass = 1 amu (atomic mass unit) neutrons: no charge, mass =
1 amu Atomic Mass of an element is approximately equal to its total
number of protons and neutrons Electrons in concentric clouds that
surround the nucleus electrons: single negative charge, very low
mass determine the chemical properties of an atom the atom is
electrically neutral because number of electrons is equal to the
number of protons valence electrons in the outermost shell
determine chemical bonding properties of an atom
Slide 14
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Isotopes Elements are defined by the number of protons in an
atom's nucleus For example, an atom with 6 protons must be carbon,
and an atom with 92 protons must be uranium Atoms of the same
element can have different numbers of neutrons; the different
possible versions of each element are called isotopes For example,
the most common isotope of hydrogen has no neutrons at all; there's
also a hydrogen isotope called deuterium, with one neutron, and
another, tritium, with two neutrons.
Slide 16
Electron Energy Shells The Bohr Model shows all of the
particles in the atom In the center is circles. Each circle
represents a single neutron or proton Protons should have a plus or
P written on them Neutrons should be blank or have an N In a circle
around the nucleus are the electrons. Electrons should have a minus
sign or an e
Slide 17
Electrons have special rules that they must follow You cant
just shove all of the electrons into the first orbit of an electron
Electrons live in something called shells or energy levels. Only so
many can be in any certain shell. Nucleus 1 st Energy Shell 2 nd
Energy Shell 3 rd Energy Shell
Slide 18
The electrons in the outer most shell of any element are called
valance electrons The electrons that are more loosely held by the
nucleus (the valence electrons, those furthest away from the
nucleus) are the ones that are gained, lost, or shared during
chemical reactions This is why it is so important to learn and
understand about valence electrons
Slide 19
So lets try it. How to draw a Lithium atom First, look at the
Periodic Table Second, determine the number of protons (Look @ the
atomic number) Then determine the number of neutrons (Atomic mass
atomic number) Then determine the number of electrons (Look @ the
atomic number) 3 Li Lithium 7
Slide 20
So lets try it. 3 Li Lithium 7 + + + Protons = 3 Neutrons = 4
(7-3=4) - - - Electrons = 3 2 in the 1 st shell, 1 in the 2 nd
shell
Slide 21
General Trends of the Periodic Table A trend is a pattern or a
repetition of particular properties Trends of the periodic table
include: Atomic Mass, Atomic Radius, Net Nuclear Charge, Ion Size,
Metallic or Non-Metallic Property, Electro-negativity, 1st
ionization energy The periodic table is arranged in a certain way
to keep elements with similar properties close together
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Slide 23
Groups vs. Periods Groups go up and down Periods go left and
right Groups share many similarities Periods show periodically
(regularly) changing properties
Slide 24
The Alkali Metals are in Group 1 but Hydrogen is not in this
group.
Slide 25
Alkaline Earth Metals are in Group 2
Slide 26
TRANSITIONAL METALS are in Groups 3 - 12
Slide 27
INNER TRANSITIONAL METALS are at the bottom and fit in as
shown
Slide 28
NON-METALS are at the right hand side of the table
Slide 29
Noble Gases are at the far right, group 18
Slide 30
First Trend-Atomic Mass Atomic mass goes higher from element to
element, with few exceptions The Group Trend is that atomic mass
increases The Period Trend is that atomic mass increases too
Because of specific properties, the Periodic Table has a
non-regular shape The elements are arranged by properties rather
than a way just make the table be uniform in shape
Slide 31
Second Trend-Atom Radius If you follow along the periodic table
for atomic radius, you find: The Group Trend for atomic radius is
that it increases down a group. The Period Trend for atomic radius
is that it decreases left to right.
Slide 32
SHOWS Atomic Sizes for Groups and Periods
Slide 33
Third Trend-1 st Ionization Energy 1 st ionization energy is
the amount of energy needed to remove a valence electron from an
entire mole of atoms and make them all into +1 ions For example To
turn a mole of Li atoms into a mole of Li+1 ions, it would take 520
kJ/mole
Slide 34
FIRST IONIZATION ENERGY FOR SOME SELECTED ATOMS Na496 kJ/mol
Mg736 kJ/mol Al 578 kJ/mol Si787 kJ/mol P 1012 kJ/mol Going across
the 3 rd period, the trend for 1 st Ionization Energy is to
INCREASE.
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Fourth Trend Electronegativity Electronegativity is the amount
of pull that an atom has for another electron in a bonding
situation Fluorine has the greatest desire of all atoms for that
electron gain Fluorine is given the rating of 4.0 on the E-N scale,
the highest Electronegativity of all elements Going down a group
the trend is towards LOWER E-N values Going across a period the
trend is towards higher E-N values It is all about HOW CLOSE IS THE
ATOM TO FLUORINE which determines the relative
electro-negativity.
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Slide 38
Exit Quiz 1). Please illustrate and describe the importance of
the typical steps that would show up in a flow chart depicting the
scientific method. 2). Compare and contrast the differences that
exist between mass and weight in science. 3). What are the three
main subatomic particles? Be able to accurately assign mass, charge
and location for each of these subatomic particles. 4). Define
atomic number and atomic mass and be prepared to calculate each
value. 5). What is the difference between an electron and a valence
electron? Why are valence electrons so important? 6). What is the
difference between ionization energy and electronegativity? Are
there any trends in the periodic table for these two values? What
are they?
