Chemistry Ch 1 & 2

chemistry

chemistry

the study of matter and the changes it undergoes

matter

anything that has mass and takes up space

model

simplifies something in the world in order to explain, describe, or represent it

presuppositions

assumptions about the world based on their worldview

worldview

answers questions that determine how we look at the world

quantitative data

data in the form of numbers determined through measuring

qualitative data

data in the form of words used to describe something

deductive reasoning

proceeds from general statements called premises to a specific conclusion

inductive reasoning

proceeds from known data to an unknown general conclusion. Uses data to to draw conclusions but it cannot prove these conclusions to be completely certain

hypothesis

a suggested explanation for a scientific question

experiment

a way to observe a natural process, sometimes under controlled conditions, to know if their hypothesis is correct

variables

factors that change

dependent variable

the factors of an experiment that change in relation to the independent variable

independent variable

the variable that the scientist changes

survey

a process that involves randomly selecting representative samples from a larger population; relies on inductive reasoning

theory

offers explanations of what we observe; can be thought of as scientific models

Scientific Law

a statement that describes a recognizable, repeating pattern in nature. It is based on observations made under many different conditions. They are often stated in mathematical equations.

physical properties

determined by how the particles that compose the material relate to one another

extensive property

does depend on the amount of substance present; e.g. weight, mass, volume, length

intensive property

a property of matter that doesn't matter how much of the substance is present; e.g. boiling point, color, temperature, density

density

the amount of matter packed into a given volume; density=mass/volume

malleability

material that can be hammered into shapes or thin sheets; most metals are malleable

ductility

materials that can be drawn into long thin wires

conductivity

the ability to conduct electricity

chemical properties

describe how matter acts in the presence of other materials; how it changes composition when sufficient energy is added to it

physical changes occur...

without changing the identity of the material

chemical changes occur...

by changing the identity of the material

pure substance

consists of only one type of matter; made up of elements of compounds

mixture

a material that can be separated into two or more pure substances by physical changes

heterogeneous mixture

appears to consist of 2 or more materials segregated into distinct regions called phases

suspensions

when particles are suspended in a liquid or gaseous phase

homogeneous mixture

show only a single phase; also known as solutions

colloid

consisting of large molecules of one substance through a second substance

colloid examples

milk, gels, mayonnaise, butter

element

a pure substance that cannot be broken down into a simpler substance my ordinary chemical means; has only one type of atom

atom

basic particles that make up elements

compound

pure substances that consist of 2 or more elements chemically combined

formula unit

crystalline arrays with repeating arrangements of ions

operational description of energy

the ability to do work

mechanical energy

objects moving or having the ability to move

thermal energy

perceived by transfer of heat energy; the sum of the kinetic energy of an object's particles

acoustic energy

if particles move in a periodic way (like waves)

electromagnetic energy

the movement of charged particles creates magnetic fields, which in turn affect other charged particles or magnetic fields; includes visible light and all other waves on the spectrum

chemical energy

when charged particles move between atoms, atoms form and break bonds with other atoms

nuclear energy

when a nucleus breaks apart or when particles are added to or removed from a nucleus

thermodynamics

the study of movement and conversion of energy, especially thermal energy

Law of Conservation of Mass-Energy/ The Law of Entropy

mass can neither be created nor destroyed; it can only change from one form to another

entropy

the measure of the dispersal energy

Second Law of Thermodynamics

all natural processes tend toward the highest entropy and minimum usable energy

internal energy

the sum of the potential and kinetic energies of its component particles; measured as temperature

heat transfer

the transfer of thermal energy between two objects or substances

heat

the quantity of thermal energy transferred from one object to another

exothermic

release of energy

endothermic

absorption of energy

Third Law of Thermodynamics

it is impossible to reach absolute zero

condensation

gas to liquid

vaporization

liquid to gas

freezes

liquid to solid

melts

solid to liquid

sublimation

solid to gas

deposition

gas to solid