chemistry

chemical change

-going to form a new substance. UP- a gas comes up DOWN- a precipitate(or solid) forms and settles at the bottom. 1. odor 2. color change 3. energy in the form of heat, light or sound ex: a car rusting

proton

is subatomic particle determines the identity of the atom. *positive charge

ATOM

is the smallest particle that retains the properties of an element.

modern model(electron cloud)

largely a mathematical model that describes electrons as waves. It also describes the space an electrons is in only as an approximate space or cloud, not a specific location

radioactive decay

losing energy by emitting radiation in a spontaneous process. very dangerous (3 types) 1. alpha decay 2. beta decay 3. gamma ray decay

radioactive decay and radioactive radiation

unstable nuclei split up a process called radioactive decay and emit radioactive radiation.

radioactive isoptopes

when the nucleus of an atom possesses either too many or too few neutrons compared to the number of protons it becomes unstable. 82 protons and greater are radioactive isotopes.

isotopes

*primary difference is the number of neutrons

radioactive and non radioactive

92 protons will be radioactive and 6 protons won't be radioactive.

radioactive

92 protons will be radioactive. 6 protons won't be radioactive. 82 protons or greater have radioactive isotopes.

Gamma ray particle

Mass=0 charge=no charge health risk= can cause the most damage. Inches of lead to stop. WAVE LENGTH high energy but short wave lengths. no mass and no energy accompany alpha and beta decay.

gamma ray decay

Np-237 makes Pu-237, Po-208 makes At-208

x rays

Similar to gamma rays. form of energy, but not produced by radioactive sources- therefore energy is lower. emitted when inner electrons are knocked out and electrons from a higher level drop down to fill vacancy.

alpha particle decay

U-236 makes Th-232, Th-229 makes Ra-225, Bi-197 makes TI-193

nuclear reaction

change in the atom's nucleus splitting atoms(Fission) or combining atoms (fusion) real world exmples: stars creating elements over lifecycle three mile island-pennsylvania

nuclear change

change in the atomic nucleus where an element can turn into a different element. *protons change* a kind of nuclear change called fission, the nucleus SPLITS. a kind of nuclear change called fusion, the neutrons and protons combine to create heavier atoms.

physical change

change state of matter. solid liquid or gas ex: pencil split, melting ice cream

nuclear fusion

combining nuclei to produce heavier elements massive amounts of energy is released(more than is released with nuclear fission). this is how the elements for the universe was formed. "combine"

e. rutherford's model(nuclear atom)

conducted gold foil experiment; discovered protons each atom contains a small,positively charged nucleus *determined most of atom is empty space most positive charges passed through gold foil 2nd subatomic particle disvorered

nuclear stability

depends on 1. # of protons* 2. ratio of neutrons to protons

dalton's model

experimented and proposed Dalton's Atomic theory. all elements composed of atoms; atoms are indivisible particles. atoms of the same elements are alike atoms of different elements are different compounds are formed by joining of atoms of 2 or more elements *didn't have the periodic table because they hadn't discovered protons yet. FIRST TO BE DISCOVERED

thomson's model(plum pudding)

first subatomic particle discovered. discovered that atoms contain negatively charged particles called electrons

types of chemical changes

forest burning, oxygen+hydrogen makes water, and iron rusting

types of nuclear changes

fusion, Po-208 to Po-208, fission, Th-229 to Ra-225

Beta particle

mass=0 charge=1- health=can penetrate a centimeter into the body. happens when neutrons convert into protons*** fast moving- don't have a lot of mass so it travels faster

alpha particle

mass=4 charge=2+ heath risk= stopped by a layer of clothing or even top layer of skin. only dangerous if you breath or eat it. slow moving and not very penetrating same composition as helium nucleus (2 protons and 2 neutrons)

types of physical changes

melting wax, freezing ice, cutting paper

nuclear fission

occurs when a neutron strikes the nucleus of either isotope, splitting the nucleus into fragments and releasing a tremendous amount of energy. "splitting"

how to get the atomic mass

protons plus neutrons

atom

smallest particle that retains the properties of an element?

neutrons or electrons

subatomic particle can change and you will still have the same atom

electron or neutron

subatomic particle can change and you will still have the same atom.

electrons

subatomic particle determines the chemical behavior of an atom.

electron

subatomic particle determines the chemical behavior of the atom. *negative charge

protons

subatomic particle determines the identity of the atom. positive charge

Bohr's model(planetary model)

suggested electrons do not fall into nucleus, because electrons can move around nucleus only in a certain fixed paths, called energy levels 1st level-2 2nd level-8 3rd level-16 3rd discovered subatomic particle

chain reaction

the fission process becomes self sustaining as neutrons produced by the splitting of atom strike nearby nuclei and produce more fission.

law of mass conservation

MATTER CAN'T BE CREATED NOR DESTROYED.