ch. 1 notes

Difference between law & theory

law—>tells you what phenomenon is

theory—>explains why phenomenon’s happening

scientific theory

best available explanation of exiting evidence/observations, makes testable predictions, can change overtime w/ new found evidence

whats a fact?

statement that can be verified

whats a law

formal statement results form repeated experiments

whats a hypothesis

a testable prediction

whats a theory

explains why a phenomena happens

whats a question

asks to test something

what are atoms

they make up matter; matter comprised of atoms

whats an element

multiple of the same atom, atom is smallest unit of an element

whats the difference between an atom & element?

atom: smallest unit of element, atoms focus on the individual nanoscale properties

element: made of atoms, elements focus on macroscopic properties of bulk samples

whats the difference between a molecule & compound?

molecule=made of 2 or more atoms of the same OR different element

compound=made of 2 or more atoms of the SAME elements

all compounds are molecules but not all molecules are compounds

what are metric system base units?

gram

meter

liter

kelvin

what does gram measure?

mass

what does liter measure

volume

what does meter measure

length

what does kelvin measure

temp

what are the base 10 prefixes?

kilo

centi

milli

micro

nano

what was Daltons Atomic Theory?

1) elements are made of small indivisible, indestructible particles called atoms

2) all atoms of an element are different from atoms of another element

3) compounds formed by combination of atoms of 2 or more elements

4) all atoms of an element are identical and have the same mass and properties

5) chemical reactions due to rearranging atoms and matter/atoms are neither created or destroyed

whats the plum pudding atomic model?

idea that electrons are embedded into an atom, similar to that of chocolate chips in a cookie

what device was used in the discovery of the electron?

cathode ray tube

what did the cathode ray tube experiment show?

-particle emerged from the cathode and moved to the anode

-particles were also deflected by magnetic fields

-type of cathode metal didn’t matter, particle have same mass charge ratio

what was the conclusion for the cathode ray tub experiment?

whatever made up the ray/beam must exist within all atoms; all atoms are divisible

-provide evidence that electrons come from within atoms

what is the planetary model of an atom?

electrons that orbit around nucleus of an atom

what was Rutherfords experiment?

-alpha particles shot at metal sheet

-some particles deflected. some went though, and some didn’t go through at all

-made new model of atom

whats the conclusion for Rutherfords experiment?

-that atoms are most concentrated in their centers/small region of space

-atoms are mostly empty space

whats an atomic #

tells how many protons are in an element—> # protons=# of electrons, mass # equal to # pros & electrons in nucleus

whats an isotope

an element that has the same # of protons & electrons but different # of neutrons, ex. Carbon w/ c-12, c-13, & c-14

whats a neutron

last subatomic particle to be found, harder to find to cause charge is neutral

why are scientific models used

can be drawing or graph or equations, they help us make sense of things & make predictions

what are the charges of an atom

atoms is neutral w/ equal # positive & negative charge particles in center w/ small nucleus containing protons & neutrons, has cloud of electrons

what’s a force

a push or pull interaction

what are the 4 fundamental forces

gravitation

electromagnetic

strong & weak forces

what is gravitational force?

attraction between objects w/ force

what are electromagnetic forces?

attraction or repulsion between things w. electric charge

are gravitational forces always or never attractive

always attractive

which force strong gravitational or electromagnetic?

electromagnetic

whats coulomb’s law

like charges repel; opposites attract

what does electrostatic force between electrons do?

gravity pulls down & electrostatic pushes up

if an object is not moving what does that mean?

that no forces are acting on OR that forces acting on it are equal & opposite

what is energy?

its the potential to do something

is energy conserved yes or no

yes

whats a system?

specific part of universe we’re looking at

how is energy made/lost?

energy is never made or lost, it can be transformed(kinetic —> potential) and transferred(thermal into surroundings)

what are the 2 types of energy

kinetic and potential

whats kinetic energy

energy that associated w/ motion

whats potential energy

energy that’s stored in a field

total energy in a system is NOT conserved, t/f

false, total energy is conserved in a closed system

what is a london dispersion force?

an intermolecular force that exists between 2 atoms; in relation to electrons of atoms

are london dispersion forces weaker for larger atoms/molecules?

no, LDF’s stronger for larger atoms/molecules because of more electrons

what does surface area of an atom have to do w/ LDF’s?

the larger the atom is/the more surface area it has, there will be greater LDF"‘s because there’s more chance for interaction