Semester Exam Vocabulary Flashcard

Scientific Method

 

the solution to a scientific problem:

State the Problem

Research

Create a hypothesis

Carry out an experiment

Data/observations

Draw a conclusion

(you can then redo the experiment to make sure results are accurate)

in other words, PRHED/OC

hypothesis
an explanation to an observation
experiment
procedure used to test a hypothesis
independant variable
variable that you can change during the experiment
Dependant Variable
variable that is oberved during the experiment
Scientific Theory
explains natural phenomenon based on large body of evidence
Scientific Law
concise statement that summarizes the results of many observations and experiments; generally accepted but can be disproven with out explanation
mass
amount of matter an object holds
volume
measure of the amount of space an object holds
extensive property

property of matter that depends on the amount of matter in a sample

examples include: mass, volume, surface area, heat and absorbed light

intensive  physical property

property that depends on the type of matter in a sample, and can identify unknown samples and describe the sample on ITS OWN

Examples:

density, color, solubility, hardness

physical property of a substance
quality or condition that can be measured or observed without changing the composition
Physical Change

some properties of the matter change but the composition does not change;

can be classified as irreversible or reversible changes

mixtures

physical blend of two or more components;

can be classified as heterogenous mixtures or homogenous mixtures

Heterogenous Mixture

the composition is not uniform throughout

(think of chex mix)

Homogenous mixture

the composition is uniform throughout

(another name for this is a SOLUTION)

element
simplest form of matter with its unique set of properties
Compound

two or more elements chemically combined in a fixed proportion;

REMEMBER: compounds can be broken down chemically into simpler substances but elements cannot

Chemical Change
change that produces matter with a different composition than the original matter
Summary of classifying matter

MATTER

substance                                     mixture

element/compound              homo/hetero

chemical property

ability of a substance to undergo a specific chemical change;

ex: iron combines with oygen to form rust so rusting is a chemical property of iron

Clues of a chemical change

transfer of energy

color change

gas production

formation of a precipate

law of conservation of matter
matter can never be created or destroyed. it simply changes from one form to another.
Difference between accuracy and precision

accuracy: measure of how close a measurement comes to the true value


precision: measure of how close a series of measurements are to one another


** if accurate but not precise, there is a technical error/human error

*** if precise but not accurate, there is a problem with the instrument/mechanical error

How to calculate percent error
exp. value-true value/true valueX 100
SI System

meter- length (m)

kilogram-mass (kg)

kelvin-temperature (K)

second-time (s)

mole-amount of substance (mol)

candela-luminous intensity (cd)

ampere-electric current (A)

Common units of energy
Joule (J) and calorie (cal)
Density

intensive property that depends only on the composition of a substance, not the amount

 

formula: mass / volume

THINK OF THE TRIANGLE

 

atom
smallest particle of an element that retains its identity in a chemical reaction

SI system prefixes– add meaning to the base units

 

Giga (G) 1,000,000,000

Mega (M) 1,000,000

kilo (k) 1,000

hecto (h) 100

deca (da) 10

deci (dc) 0.1 or one tenth

centi (c) 0.01 or one hundreth

milli (m) 0.001 or one thousandth

micro (weird m) 1/1,000,000

nano (n) 1/1,000,000,000


 

Mass vs. Weight

mass- measured with a balance and does not depend on gravity

 

weight- measured with a scale, not used in chemistry and depends on gravity

Law of conservation of energy
energy can neither be created nor destroyed. it simply changes from one form to another.
intensive chemical reaction

property that doesnt matter on amount of sample, can identify unknowns and can describe how the sample reacts in a chemical reaction

examples:

reactions with acids

allotrope

Different forms of a pure element with different properties

carbon allotropes:

coal, diamond, graphite, charcoal

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