Glossary of Intro to Chemistry - Chapter 1

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How many different elements are known, and how many occur naturally?
114 different elements known

88 occur naturally
Name the three particles in an atom?
proton + with a mass of 1836
Electron - with a mass of 1
Neutron no charge with a mass of 1839
What is the function of a neutron?
unknown - may be to keep atom from flying apart.
Which part of an atom determines chemical behavior and why?
Electrons determine chemical behavior because electrons are the part of the atom that intermingle when atoms combine.
What is Dalton's Atomic Theory?
1. Elements are made of tiny particles called atoms.
2 All atoms of a given element are identical.
3. Atoms of a given element are different from those of any other element.
4. Atoms of one element can combine with atoms of other elements to form compounds (A given compound always has the same relative numbers and types of atoms).
5 Atoms are indivisible in chemical processes (not created or destroyed). Instead the chemical process simply changes the way atoms are grouped together.
What is a compound?
A distinct substance that is composed of the atoms of two or more elements. It always has exactly the same relative masses of these elements.
What is an isotope?
Atoms of the same element with the same number of protons but a different number of neutrons.
What is the Mass Number?
The total number of protons and neutrons in an element. Denoted before the element symbol and superscript.
What is the atomic number
The number of protons in a nucleus. Denoted before the element in subscript.
Define Chemistry.
the science that deals with the materials of the universe and the changes that these materials undergo.
Why is Chemistry often called the central science?
Because most of the phenomena that occur in the world involves chemical changes.
What are the three steps to the scientific method?
1. State the problem - and collect data
2. Formulate hypotheses.
3. Perform experiments
What is a hypothesis?
A possible explanation
Why do we perform experiments?
To test the hypotheses.
What is the difference between an observation and a theory?
Observations are witnessed and can be recorded.

Theories are interpretations - possible explanations, changes with new info.
What is a natural law?
A summary of observed, natural behavior.
What is the difference between Law and theory?
Law - summary of observed (measurable) behavior. What Happens

Theory - an explanation of behavior. Why it happens.
If all scientists use the scientific method to try to arrive at a better understanding of the world, why do so many debates arise among scientists?
Scientists are human - bias, error, interpretation occur. Theroies are simplifications and not 100% accurate, leaving data open to interpretation.
Observations can be _________ or ___________.
Quantitative (measurement - uses a number) Qualitative (regarding quality )
What is a theory?
A theory is a set of tested hypotheses that gives an overall explanation of some part of nature.

A Theory is developed after we have enough support from experiments for a hypothesis.

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