chemistry class ch.1 Flashcards
(24 cards)
Chemistry
The science that seeks to understand the behavior of matter by studying properties of atoms and molecules.
Hypothesis
- is a tentative interpretation or explanation of the observations
- A good hypothesis is falsifiable (could be proven wrong)
- The results of an experiment may support a hypothesis or prove it wrong in which case the scientist must modify or discard the hypothesis.
Scientific Law
- A brief statement that summarizes past observations and predicts future ones.
- Allows you to predict future observations so you can test the law with experiments.
scientific method
path of discovery that leads from question and observation to law or hypothesis to theory, combined with experimental verification of the hypothesis and any necessary modification of the theory
theory
well-substantiated, comprehensive, testable explanation of a particular aspect of nature
energy
is the only thing that is not matter. does not have mass
Atoms
constitute the fundemental building blocks of matter
Basic unit of a chemical Element
Molecules
two or more atoms combined in specific arrangments
Pure substance
substances that are made of only one type of atom or only one type of molecule
Can be ether an Element or a compound
Elements
A substance that cannot be broken down into a simpler substances.
- if combined with itself, it is still considered an element not a compund
- Example, H2, 02,N2,F2
Compounds
A substance that is composed of two or more different elements (fixed composition)
Mixtures
Different compounds can be seperrated without altering the composition
Example multiple elements mixed together
Homogenous
uniformall throughout
Multiple substances mixed together but appears to be one substance!
Example
H2O and NaCl
Heterogenous
compostion varies/ visible distinction
Example
H2O and Sand
Give an Example of a Molecular Element Also known as a
Diatomic Elements.
Why is it not a compound?
H2
N2
O2
F2
Because it is combined with itself not another element making it not a compound
What is a compound
When two different elements are combined with one another
Example H2O
NaCl
Physical Change
Changes that alter only the state of apperance, but not the composition.
Chemical Change
Changes in the composition of matter
Physical property
Is displayed by the substance without changing its composistion.
example,
- Smell of gasoline
- odor
- taste
- color
- melting point
- boiling point
- density
Chemical Property
Is a property that a substance displays only by changing its compostion via a chemical change (or chemical reaction)
Examples,
- Flammabillity of gasoline
- corrosiveness
- Acidity
- Toxicity
The scientific Method
List steps in chronological order
Is a set of general principles that helps to describe how a scientists thinks.
- Make observations
- Propose a hypothesis
- Experiments
- Conclusion (indicates wether Hypothesis is true or false)
Observation (also known as data)
- Description of the charecteristics or behavior of nature
- leads to the formation of a hypothesis
Theory
- Is a model for the way nature is and tries to explain not merly what nature does, but why.
- are validated by experiments
- can never be conclusively proven because some new observation or experiment always has potential to reveal a flaw.
- general explanation for characteristics and behavior of nature
- models of nature and can be used to predict future observations.
ion
An atom that has a different number of electrons than protons
The charge is no longer neutral.
The atom is positive or negative
