CAGAYAN STATE UNIVERSITY – ANDREWS CAMPUS
Professor: Mrs. Jocelyn Soriano Diesta
WEEK 1: PREVIEW OF DESCRIPTIVE AND THEORETHICAL CHEMISTRY
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CHEMISTRY
study of matter and the changes it undergoes.
does not only investigates the qualities of matter, but also how
and why it changes.
often called the “central science.”
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It is central because a basic knowledge of chemistry is
essential to our way of life. Without it, we would be living
shorter lives in what we would consider primitive conditions.
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FIVE MAIN BRANCHES OF CHEMISTRY
It is a scientific study that plays a pivotal role in our understanding
of synthetic and physical phenomena and, as follows, both the
material and natural world.
Throughout history, chemists have come together to work with
other skilled experts in their fields for a single reason: to solve
grand challenges in society.
Unfortunately, some chemicals can harm our health or the
environment. As educated citizens and consumers, it is in our
best interest to understand the profound effects, both positive
and negative, that chemicals have on our lives and to strike an
informed balance about their uses.
CONTRIBUTION OF CHEMISTRY TO SOCIETY
1. PHYSICAL CHEMISTRY
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Study of the physical properties of molecules, and their
relation to the ways in which molecules and atoms are put
together.
2. ANALYTICAL CHEMISTRY
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Study involving how we analyze the chemical components of
samples.
3. ORGANIC CHEMISTRY
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Study of carbon-containing compounds.
4. INORGANIC CHEMISTRY
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Study of elements and compounds other than carbon or
hydrocarbons.
5. BIOCHEMISTRY
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Study of chemical processes in living organisms.
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SIGNIFICANCE
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Everything in our environment is made of matter. Chemistry is
significant in our civilization because it affects our basic needs for
food, clothing, shelter, health, energy, and clean air, water, and
soil, among other things.
Chemistry lies at the heart of many matters of public concern:
improvement of health care, conservation of natural resources,
protection of the environment, and provision of our daily needs for
food, clothing, and shelter.
Using chemistry, we have discovered pharmaceutical chemicals
that enhance health and prolong lives. We have increased food
production through the use of fertilizers and pesticides, and we
have developed plastics and other materials used in almost every
facet of our lives, from electronics to sporting equipment to
building construction.
Chemical discoveries and their applications have played a pivotal
role in the advancement of humankind and will continue to have a
profound impact on health, the environment, industry, agriculture,
science, and technology.
Source of knowledge and skills
Field of communication
Transportation
Sophisticated equipments / Materials
Increases the agricultural product
Crimes (provide evidences to solve it)
Environmental sanitation
Supply to Food
Development of life-saving medicines
Innovation of technologies
Entertainment
THE SCIENTIFIC METHOD
Used by scientists to search for answers to questions and
solutions to problems.
Consists of making observations, formulation hypotheses,
and designing experiments; lead to additional
observations, hypotheses, and experiments in repeated
cycles.
STEPS IN THE SCIENTIFIC METHOD
STEP 1: MAKE OBSERVATIONS
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Can be qualitative and quantitative.
STEP 2: FORMULATE A HYPOTHESIS
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Scientists begin by forming a hypothesis, a tentative
explanation for the observations.
May not be correct, but puts into a form that can be
tested.
Suitable experiments can be designed to choose
between two alternatives.
STEP 3: DESIGN AND PERFORM EXPERIMENTS
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After a formulating a hypothesis, scientists conduct
experiments to test its validity.
Experiments are systematic observations or
measurements, made under controlled conditions (in
which a single variable changes)
STEP 4: ACCEPT OR MODIFY THE HYPOTHESIS
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After experimenting, it enables scientists to determine
whether the hypothesis is valid
If it is not, the hypothesis must be modified
STEP 5: DEVELOPMENT INTO A LAW AND/OR THEORY
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CONCERNS
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Chemistry is about more than discovery—the science and art of
matter involve both creation and destruction.
More experimental data are then collected and
analyzed, and scientists may think that the results are
dependable to merit being summarized in a law.
Law is a verbal or mathematical description of a
phenomenon that allows for general predictions.
MARK DAVE VIERNES | BSMLS 1F
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Law simply says what happens, not address the
question of why
SUBSTANCE
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ADDITIONAL INFORMATION
Scientists can start in any step he wishes. He/she can start
with a hypothesis, rather than by making direct observations.
SI UNITS OF MEASUREMENT
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is a form of matter that has a definite (constant) composition and
distinct properties.
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Substances can be either elements or compounds.
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Element - a substance that cannot be separated into
simpler substances by chemical means.
Compound - a substance composed of atoms of two or more
elements chemically united in fixed proportions.
INTERNATIONAL SYSTEM OF UNITS (SI)
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Metric system used in science, industry, and medicine
Every field of science involves taking measurements and
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communicating them to other (we need to speak the same basic
language)
Used around the world
Scientific method of expressing the magnitudes or quantities of
important natural phenomena.
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PREFIXES USED WITH SI UNITS
THREE STATES OF MATTER
In a solid, molecules are held close together in an orderly fashion
with little freedom of motion
Molecules in a liquid are close together but are not held so rigidly
in position and can move past one another.
In a gas, the molecules are separated by distances that are large
compared with the size of the molecules.
PHYSICAL AND CHEMICAL PROPERTIES OF MATTER
Substances are identified by their properties as well as by their
composition.
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Color, melting point, and boiling point are physical
properties.
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All measurable properties of matter fall into one of two additional
categories: extensive properties and intensive properties.
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The measured value of an extensive property depends
on how much matter is being considered.
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Mass, which is the quantity of matter in a given sample
of a substance, is an extensive property. More matter
means more mass.
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Volume defined as length cubed, is another extensive
property.
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The measured value of an intensive property does not
depend on how much matter is being considered.
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Density defined as the mass of an object divided by its
volume, is an intensive property.
WEEK 2: NATURE OF MATTER AND ENERGY
MATTER
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anything that occupies space and has mass.
Matter includes things we can see and touch (such as water,
earth, and trees), as well as things we cannot (such as air).
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Thus, everything in the universe has a “chemical”
connection.
MASS AND WEIGHT
MIXTURE
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A physical property can be measured and observed without
changing the composition or identity of a substance.
On the other hand, the statement “Hydrogen gas burns in oxygen
gas to form water” describes a chemical property of hydrogen,
because to observe this property we must carry out a chemical
change, in this case burning.
is a combination of two or more substances in which the
substances retain their distinct identities.
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Mixtures are either homogeneous or heterogeneous.
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Homogenous - composition of the mixture is the same
throughout.
Ex: When a spoonful of sugar dissolves in water we
obtain a homogeneous mixture.
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Heterogeneous - the composition is not uniform.
Ex: If sand is mixed with iron filings, however, the sand
grains and the iron filings remain separate
The terms “mass” and “weight” are often used interchangeably,
although, strictly speaking, they are different quantities.
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Mass pertains to the quantity of the object.
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Weight is the force that gravity exerts on an object.
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Gravity is not involved.
Chemists are interested primarily in mass, which can be
determined readily with a balance; the process of measuring
mass, oddly, is called weighing.
MARK DAVE VIERNES | BSMLS 1F