why is studying atoms difficult?
studying atoms is difficult because atoms are microscopic
when was the idea of matter formed/proposed?
430 B.C.
atom
the smallest particle that can still be considered an element
Dalton's Atomic Theory
atoms
v
smooth hard balls that cannot be broken into smaller pieces
v v v
same element
compounds are formed by atoms of it combine in a specific ratio
different element
vv
alike and same mass
different and different mass
v v
cannot be changed cannot be ch
who discovered electrons/when?
J.J. Thomson
1897
what charge do electrons have?
negative charge
-1
who discovered the atoms' nucleus/when?
Ernest Rutherford
1911
who discovered protons?
Ernest Rutherford
what charge do protons have?
positive charge
1
HINT: Protons and Positive start with Ps
Bohr's Model
-electrons are only found in specific orbits around the nucleus
-each possible electron has a fixed energy
energy level
the specific amount of energy an electron has
HINT: think Energy level and Electron--both start with Es
who discovered the neutron and when?
James Chadwick
1932
what charge do neutrons have?
Neutral charge
0
HINT: NEUTRon and NEUTRal are almost the same word
relate protons and electrons
-the number of protons = the number of electrons
-positive charge from proton = negative charge from the electron
-balance: makes the atom neutral
order the following from the least mass to the greatest (proton, neutron, and electron)
-electron (-1)
-neutron (0)
-proton (1)
what is the unit to measure atomic mass?
atomic mass units (amu)
relate the atomic number and the number of protons
-a proton/neutron has a mass = about one amu
-the number of protons in the nucleus determines the atomic number
-the number of protons in the nucleus = the atomic number
give an example of an atomic number and the number of protons
-carbon:
-protons: 6
-atomic number: 6
-iron:
-protons: 26
-atomic number: 26
isotope
atoms with the same number of protons and different number of neutrons
give and example of an isotope
carbon-12
-6 protons
-6 neutrons
mass number
the sum of the protons and neutrons in the atom
what is a rule for making an atom neutral (one with 0 extra charge)?
when all 3 particles have the same amount
-protons = 7
-neutrons = 7
-electrons = 7
what is the rule for making a +ion (positive ion, one with extra positive charge)?
when there are more protons than electrons
-p = 6
-n = 7
-e = 5
what is the rule for making a -ion (negative ion, one with extra negative charge)?
when there are more electrons and/or neutrons than protons
-p = 6
-n = 7
-e = 7
what is the rule for determining the mass?
the number of protons and neutrons combined = atomic mass
happy atom
when there are the maximum number of electrons in the outer shell of the atom
makes the atom bond with another element
why don't models accurately represent the true size and distances in your atom?
particles within the atom are constantly moving and an atom is so small that no microscope can see, so I cannot accurately scale the model. also we used Bohr's model as oppose to the more recent, accurate cloud model of the atom.