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Flashcards in chemistry class ch.1 Deck (24):
1

Chemistry

 

The science that seeks to understand the behavior of matter by studying properties of atoms and molecules.

2

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.

3

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.

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4

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

5

theory

 

well-substantiated, comprehensive, testable explanation of a particular aspect of nature

6

energy

is the only thing that is not matter. does not have mass

7

Atoms

constitute the fundemental building blocks of matter

Basic unit of a chemical Element

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8

Molecules

two or more atoms combined in specific arrangments

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9

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

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10

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

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11

Compounds

A substance that is composed of two or more different elements (fixed composition)

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12

Mixtures 

Different compounds can be seperrated without altering the composition

Example multiple elements mixed together

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13

Homogenous

uniformall throughout

Multiple substances mixed together but appears to be one substance!

 

Example

H2O and NaCl

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14

Heterogenous

compostion varies/ visible distinction

 

Example

H2O and Sand

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15

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

16

What is a compound 

When two different elements are combined with one another 

Example H2

NaCl

 

17

Physical Change

Changes that alter only the state of apperance, but not the composition.

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18

Chemical Change

Changes in the composition of matter

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19

Physical property 

Is displayed by the substance without changing its composistion.

example,

  • Smell of gasoline
  • odor
  • taste 
  • color
  • melting point 
  • boiling point
  • density

20

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

21

The scientific Method 

List steps in chronological order

Is a set of general principles that helps to describe how a scientists thinks.

  1. Make observations 
  2. Propose a hypothesis
  3. Experiments
  4. Conclusion (indicates wether Hypothesis is true or false)

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22

Observation (also known as data)

  • Description of the charecteristics or behavior of nature
    • leads to the formation of a hypothesis

23

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.

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24

ion 

An atom that has a different number of electrons than protons

 

The charge is no longer neutral. 

The atom is positive or negative

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