Physical Science Unit 4
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Physical Science Unit 4
matter is made up of particles called ___
who suggested the universe was made of indivisible units?
Greek philosopher Democritus
unable to be cut or divided
Dalton's atomic theory
all atoms of a given element were exactly alike, and atoms of different elements could join to form compounds
law of definite proportions
a chemical compound always contains the same elements in exactly the same proportions by weight or mass
whose theory is considered the foundation for modern atomic theory?
for any given water sample, the proportions of hydrogen and oxygen by mass are ___
who conducted an experiment that suggested atoms were not indivisible?
mysterious rays in vacuum tubes
according to Thomson's experiment, cathode rays are made of ___ particles that came from ___
1. negatively charged
2. inside atoms
cathode has what type charge?
anode has what type charge?
negatively charged particles inside the atom
what did Rutherford propose?
most of the mass of the atom was concentrated at the atom's center
positively charged, dense core of the atom
nucleus contains particles called ___ and ___
protons and neutrons
protons have ___ charge
neutrons have ___ charge
the 3 main subatomic particles are distinguished by?
location in the atom
tiny, negatively charged particles moving around outside the nucleus
the mass of an electron is ___ than that of a proton or neutron
how many protons does a hydrogen atom have?
how many protons does a helium atom have?
how many protons does lithium have?
if an atom gains or loses electrons, it becomes ___
force attracting positive and negative charges
number of protons in the nucleus of an atom
sum of the numbers of protons and neutrons in the nucleus of an atom
an atom that has the same number of protons as other atoms of the same element, but has a different number of neutrons
what does the number 235 represent in U-235?
unit of mass that describes the mass of an atom or molecule - equal to 1/12 the mass of a carbon-12
unified atomic mass unit (amu)
weighted average of an element
average atomic mass
collection of a very large number of particles
mass in grams of one mole of substance
who suggested that the energy of each electron was related to the electron's path around the nucleus?
according to Bohr's new atomic model, how do electrons behave?
can the exact location of an electron be determined?
region in an atom where there is high probability of finding electrons
what does the number of energy levels that are filled in an atom depend on?
number of electrons
electrons in the outer energy level of an atom
valence electrons determine what type of properties of an atom?
four kinds of orbitals
which orbital is the simplest?
orbital shaped like a sphere
orbital shaped like a dumbbell
how many possible p orbitals are there?
how many possible d orbitals are there?
how many possible f orbitals are there?
when do electrons jump between energy levels?
when an atom gains or loses energy
lowest state of energy of an electron
when does an electron move to an excited state?
when it gains energy
a unit or quantum of light
energy of a photon is related to what?
wavelength of the light