11 Atoms the Basic Unit of Matter Flashcards
matter is made up of
atoms
are the smallest whole particles
atoms
basic unit of matter
atoms
smaller particles that compose the atom
subatomic particles
dense central core of the atom
nucleus
subatomic particles found in the nuclei
nucleons
positively charge particle
protons
makes the identity of an atom
protons
equal to the number of protons inside the nucleus
atomic number
neutral particles
neutrons
atoms of the same element but have DIFFERENT number of neutrons
isotopes
determines the stability of the atom
isotopes
H1
protium
H2
deuterium
H3
tritium
still smaller particles that compose the protons and neutrons
quarks
According to quark theory, _____ quarks are needed to make a proton or a neutron
3
reacts and bonds with other electrons of atoms to form substances
electrons
layers; orbits; energy levels
electron shells
shells farther from the nucleus can hold
___ electrons than the innermost shells
more
greek philosopher (470 – 380 BC) who is the father of modern atomic thought
democritus
proposed that matter cannot be divided into smaller pieces forever
democritus
claimed that matter was made of small, hard particles called “atomos”
democritus
created the very first atomic theory
john dalton (1808)
english school teacher who performed many experiments on atoms
john dalton
viewed atoms as tiny, solid balls
john dalton
john dalton’s atomic theory
- atoms are tiny, invisible particles
- atoms of one element are all the same
- atoms of diff elements are different
- compounds form by combining atoms
dalton’s theory revisions
- atoms aren’t indestructible; they consist of still smaller particles.
- the atoms of one element may
differ in mass
smaller particles that made up the atom
sub-atomic particles
not fundamental; divisible; positive
protons
made of two up quarks and one down quark
protons
not fundamental; divisible; neutral
neutrons
made of one up quark and two down quarks
neutrons
fundamental; indivisible
electrons
still not known to consist of other particles
electrons
using his expertise in electromagnetic theory, he was able to determine the ratio of electron’s charge to its mass:
e- charge/m = − 𝟏.𝟕𝟔 𝐱 𝟏𝟎𝟖 𝐂/g
Sir Joseph John Thomson
oil-drop experiment
Robert Andrews Millikan
mass of an electron
mass of an e- = (e-charge) ÷ (e-charge/mass)
negatively charged particles
electrons
-1 is the unit of negative charge
electrons
value of the unit charge
electrons
e = -1.60210 x 10-19 C
electrons
has a mass of 9.109 x 10-28 g or 0.000549 amu
electrons
positively charged particles
protons
+1 is the unit of positive charge and
relative value
protons
has a mass of 1.673 x 10-24 g or 1 amu
protons
discovered electrons
JJ Thomson (1897)
first scientist to show that the atom was made of even smaller things
JJ Thomson
proposted the existence of a (+) particle
JJ Thomson
his atomic model was known as the “raisin bun” model
JJ Thomson
atoms are mostly made of (+) charged material, like dough in a bun; the (-) charged electrons are found inside the dough
raisin bun model by JJ Thomson
gold foil experiment
rutherford and co.
atom had a very dense (+) center; ____ called it a nucleus
rutherford
mostly empty space
rutherford’s nuclear model
has a small, positive nucleus containing protons
rutherford’s nuclear model
negative electrons are scattered around it
rutherford’s nuclear model
improved on Rutherford’s model
niel bohr (1913)
proposed that electrons move around the nucleus in specific layers/shells
niel bohr
every atom has a specific number of shells
niel bohr
electrons move in definite orbits around the nucleus
bohr’s planetary model
proposed by Erwin Schrödinger
schrodinger’s wave mechanical model
electrons move like waves around the nucleus
schrodinger’s wave mechanical model
atomic model that has electrons moving around the nucleus in a cloud
modern
a modified wave mechanical model
born’s electron cloud model
spherical cloud of varying density which shows where an electron is more or less likely to be
born’s electron cloud model
discovered neutrons
james chadwick (1932)
while working with rutherford, discovered particles that had no charge; he called them neutrons
james chadwick
neutral, no electric charge
neutrons
the other particle inside the nucleus aside from the protons that makes up the atomic mass
neutrons
has a mass of 1.675 x 10-24 g or 1 amu
neutrons
identity number
atomic number
equal to the number of protons in the nucleus
atomic number
equal to the number of electrons in the
neutral state
atomic number
represented by capital letter “Z”
atomic number
the sum of the number of neutrons and protons in an atomic nucleus
mass number
represented by letter “A”
mass number
the mass of an atom expressed in atomic mass units (µ)
atomic mass
atoms that gain or lose electrons,
thereby forming charged particles
ions
two types of ions
cations (+) and anions (-)
formula for atomic number
Z = p
formula for mass number
A = Z, A = p + n
formula for neutrons
n = A - Z or p
formula for e-
p if the electrical charge is 0 (neutral state)
formula if the charge is + (cation)
p - charge = #e-
formula if the charge is - (anion)
p + charge = #e-
p + n =
atomic mass
atoms are
neutral
protons =
electrons
do protons = atomic number?
yes
what make up the identity of an atom?
number of protons
