MIDTERM STUDY (Unit 1) Flashcards by Evelyn Cardenas

The steps of the scientific method (5):

make observation & stating a problem
form hypothesis
test hypothesis
record /analyze data
-draw conclusion

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Qualitative Observations:

using the senses to observe qualities - non-numerical properties

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Quantitative Observations:

measurements or quantities- numerical

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Independent Variable:

the variable that is changed during the experiment

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Dependent Variable:

the variable that is observed during the experiment (result of changing the independent variable)

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Science:

the search for scientific knowledge

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Technology:

the application of science (making it useful)

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Scientific Theory:

an explanation abt the natural world (not a guess), based on hypothesis and observations supported by testing
-explains how and why

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Scientific Law:

a statement abt the natural world
- does not explain how or why

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Hypothesis:

proposed explanation that is not tested

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Theory:

well-tested explanation

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All matter is composed of what:

particles that are in constant motion

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More energy in particles =

more space between them

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States of matter in order from less energy to more energy

Solid, Liquid, Gas

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All particles of matter have..

energy

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Temperature:

measure of the average kinetic energy of the particles

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Increase Temp. =

Increase Energy

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States of matter in order from strong attractive force to weak

Solid, Liquid, Gas

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Chemistry:

study of the composition of matter and the changes it undergoes

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Units of matter:

Atom and Element

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Atom:

smallest unit of an element that maintains chemical identity of that element

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Element:

pure substance that cannot be broken down + made up of only one type of atom

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Matter:

Anything that has mass and volume

Mass:

measure of the amnt of matter

Volume:

amnt of three dimensional space an object occupies

Characteristics of Solid:

-Definite shape/volume -packed close together -vibrate in a fixed position -very strong force of attraction / low energy

Characteristics of Liquid:

-definite volume, no definite shape - close together but slide past one another -- move past another, slide, flow - Strong force of attraction, medium energy

Characteristics of Gas:

-no definite volume, no definite shape - spread out as far as possible -move with great speed -weak force of attraction, very high energy

Pure substance has-

a fixed composition (composed of just one type of particle) + are either compounds or elements

Elements:

-simplest pure substance -cant be broken down by ordinary means -made up of only one atom

Compounds

-pure substance-definite composition -2 or more elements combined through chemical reaction -Composed of definite group of molecules/ ions that are chemically bonded

Chemical and physical properties of a compound differ from:

those of the elements that make up the compound

Mixture:

-physical combo of 2 or more substances -identities/properties of individual substances are retained -can be separated by physical means

Two types of mixtures:

Homogeneous and heterogeneous

Heterogeneous mixture:

-mixture does not appear the same throughout -particles large enough -not uniform

Homogenous mixture:

-mixture that appeares same throughout ex.air

Filtration:

uses physical property of SIZE to filter mixture

Distillation:

uses physical property of BOILING POINT to separate liquid mixture.

Evaporation:

uses physical prop of VAPORIZATION POINT (evaporation/boiling)

Decanting:

-uses physical property of STATE OF MATTER -liquids are fluid and SOLUBILITY to separate mixture

Diatomic elements:

are only found in pairs when in pure state (the 7 in chart)

Physical properties:

properties that can be observed/measured without changing substance into another substance ex. density, boilig/melting point, texture, shape, color

Extensive properties (M.V.L):

Depend of amnt of matter present EX. mass,volume,length

Intensive properties:

do not depend on the anmt of matter present EX. density, color, hardness

Chemical properties:

properties that relate to a substance's ability to change - produce new substance ex.rusting, tarnishing, supports combustion, reacts with acids, water, or ocygen

Physical change:

original substance is not chemically changed +original substance is physically altered, but still present ex. evaporation, melting, dissolving salt in water, cutting

Chemical Change (reactions):

Og substances= reactants New substance formed= products

Density:

Ratio of mass to volume of a substance

g/cm 3 :

used for solids

g/mL:

liquids and gases

Separation techniques (F.E.D.D.) :

-Filtration -Evaporation -Distillation -Decanting

two types of physical properties:

Intensive and extensive

Difference between compounds and mixtures?

Compound: have a definite composition Mixtures: have no definite composition

What is a Homogeneous mixture also called:

a solution

Two types of variables:

Intensive and Extensive