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Chemistry Chapters 1 and 3 Test
Terms in this set (59)
What is the scientific method?
a way of learning that emphasizes observation and experimentation
What do observations involve?
measuring or observing some aspect of nature
What are hypotheses?
are tentative interpretations of the observations./ an educated guess
What are laws/ what do they do?
summarize the results of a large number of observations
What are theories?
models that explain and give underlying causes for observations and laws
What must be tested and validated by experiments?
hypotheses, laws, and theories
What is a scientific law?
a brief statement that synthesizes past observations and predicts future ones.
What does the law of conservation of mass state?
"In a chemical reaction matter is neither created nor destroyed."
What are the most powerful pieces of scientific knowledge?
Established theories with strong experimental support
From a molecular point of view, explain why soda pop fizzes.
Under pressure, gaseous carbon dioxide molecules are forced to remain mixed with liquid water molecules in a sealed container.
When the can is opened, the pressure is released, and carbon dioxide molecules escape out of the soda mixture, creating bubbles.
The connections that hold atoms to each other are called ___.
What is the difference between a scientific hypothesis and a theory?
A scientific hypothesis is a testable assumption; a theory is an accepted model used to more fully explain past observations and laws.
What is matter?
anything that has mass and takes up space
What is matter composed of?
What are atoms?
submicroscopic particles that are the fundamental building blocks of matter
When atoms are bonded together what do they form?
what are molecules?
two or more specific atoms joined together to one another in specific geometric arrangements.
atoms or molecules pack close to each other in fixed locations.
atoms or molecules are close to each other but are free to move around and by each other.
atoms or molecules are separated by large distances and are free to move relative to one another.
Atoms or molecules arranged in geometric patterns with long-range, repeating order.
Atoms or molecules do not have long-range order.
No chemical transformation can decompose an element into simpler substances. T/F
Since the atoms or molecules that compose gases are not in contact with one another, gases are...
what is a pure substance made of?
composed of only one type of atom or molecule.
what is a mixture made of?
composed of two or more different types of atoms or molecules combined in variable proportions.
What is an element?
a pure substance that cannot be broken down into simpler substances
what is a compound?
A pure substance composed of two or more elements in fixed definite proportions.
can compounds be decomposed into simpler substances
what is the difference between a compound and a mixture?
A compound is a pure substance composed of different atoms that are chemically united (bonded) in fixed definite proportions. Whereas a mixture is composed of two or more different types of atoms or molecules (substances) combined in variable proportions.
A pure substance may be either an ____ or a ____.
When matter contains two types of atoms it may be a ____ or a ____.
pure substance (compound); mixture
Mixtures may be composed of two or more ____, two or more ____, or a combination of both.
What is the difference between an element and a compound?
An element is a pure substance that cannot be broken down into simpler substances. Whereas a compound is a a pure substance composed of two or more elements in fixed definite proportions that can be broken down/ decomposed into simpler subtances.
Compounds can be decomposed into simpler substances. T/F
Elements can be broken down into simpler substances. T/F
What is a homogeneous mixture?
uniform compositions because the atoms or molecules that compose them mix uniformly; the composition in the same throughout
What is a heterogeneous mixture?
a mixture in which the composition is not uniform throughout; he composition varies from one region to another
A mixture can be ____ or ____.
homogeneous or heterogeneous
what is a physical property?
one that a substance displays without changing its compostion
what is a chemical property?
one that a substance displays only through changing its composition
What does not change when the substance displays its physical properties?
The atomic or molecular composition of a substance
what are state changes and what are they always considered to be?
state changes—transformations from one state of matter to another (such as from solid to liquid)—are always physical changes.
What occurs in a physical change?
matter changes its appearance but not its composition
State changes are always a ____ change.
what occurs in a chemical change?
matter changes its composition.
when does matter undergo a chemical change?
when it undergoes a chemical reaction.
in a chemical reaction, the substances present before the chemical change are called the?
the substances present after the change are called the?
what is the difference between a physical and chemical change?
In physical changes, the atoms that compose the matter do not change their fundamental associations, even though the matter may change its appearance. Whereas in a chemical changes, atoms do change their fundamental associations, resulting in matter with a new identity.
A physical change results in?
a different form of the same substance
A chemical change results in?
a completely new substance
Matter is neither destroyed nor created in a ____ reaction.
What is the difference between a chemical and physical change?
A physical change results in a different form of the same substance. A chemical change results in a completely new substance.
During physical and chemical changes what remains constant?
the total amount of matter
What are the steps of the scientific method?
Observation, question, hypothesis, experiment, theory, law (be able to make the chart from your notes)
What is the difference between an atom and an element?
An element is a pure substance that cannot be broken down into simpler substances. Whereas an atoms are submicroscopic particles that are the fundamental building blocks of matter
what is conservation of matter/mass?
Whether the changes in matter are chemical or physical, matter is always conserved. In a chemical change, the masses of the matter undergoing the chemical change must equal the sum of the masses of matter resulting from the chemical change.
During physical and chemical changes, the total amount of matter remains constant
conservation of mass
THIS SET IS OFTEN IN FOLDERS WITH...
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Chemistry H Review Multiple Choice
chemistry chapter 1
Chemistry Chapter 2
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