Studied by 20 peopleAtomic Structure notes from all google slides.
Democritus
Was the first person to think about an atom's existence.
Democritus believed
matter is composed of atoms, tiny indivisible particles
Democritus didn't have
experimental evidence to support his thoughts.
Aristotle was
A very famous and popular Greek philosopher who rejected the idea of atoms
Aristotle was so influential that
he was able to have Democritus' ideas rejected
But Aristotle and Democritus both agreed that
matter is made of basic components.
John Dalton
developed modern atomic theory
Dalton's Atomic Theory 1st Point
All elements are composed of indivisible particles called atoms.
Dalton's Atomic Theory 2nd Point
Atoms of the same element are identical. The atoms of any one element are different from those of another. (This is partially incorrect, as Isotopes exist.)
Dalton's Atomic Theory 3rd Point
Atoms of different elements mix or combine in whole number ratios.
Dalton's Atomic Theory 4th Point
Chemical reactions occur when atoms separate, join, or rearrange.
In a chemical reaction, atoms of one element NEVER
change into another.
Cathode Ray Tube Experiment was made by J.J Johnson. In the experiment there was
A tube with inert gas, and two plates, a positive and a negative.
The particles in the gas were attracted to the
positive plate.
Therefore, the particles MUST
have a negative charge.
J.J. Thomson
Discovered the electron
J.J. Thomson had believed that the atom was ____________________________________________________________ from his experimental evidence.
a solid positive sphere with electrons shoved into the sides of it.
JJ Thomson Model was named
Plum Pudding Model
Robert Millikan
used the oil-drop apparatus to determine the charge of an electron
The mass of an electron is at least
1000 times smaller than the lightest atom. The mass of the electron is negligible.
Ernest Rutherford
Gold foil experiment
Ernest Rutherford used the gold foil experiment to
discover the nucleus.
Ernest Rutherford had shot high energy beam of
alpha particles into gold foil.
Most of the alpha particles went through he concluded...
The atom is mostly empty space.
Few particles were deflected at small angles he concluded...
The alpha particle came close to something small and positive (nucleus).
Very rarely particles were deflected at large angles he concluded...
The alpha particles hit a small, very dense, and positively charged center (nucleus).
Niels Bohr's Atom
electrons orbit in energy levels around the protons in the nucleus like our solar system.
Erwin Schrödinger
Electron cloud model: doesn't stay in fixed orbits, rather stay in a three dimensional space.
Electrons do not follow
fixed orbits.
Electron Bohr vs Electron Cloud
Electron Bohr stays in fixed orbits like the the solar system, it doesn't diverge from it's path. While an electron cloud is a three dimensional region, the energy levels still exist, but they don't orbit in fixated states.
Werner Heisenberg
Developed an uncertainty principle
uncertainty principle
we cannot determine the speed and position of the electrons around the nucleus.
quantum mechanics theory
electrons are found in specific orbitals
James Chadwick
discovered the neutron.
neutron
no charge
Atomic Number
the number of protons in the nucleus of an atom
An atomic number is always
a whole number
number of protons is equal to
number of electrons
the number of protons
will never change
Atomic Mass
The average mass of all the isotopes of an element
An Atomic Mass
will have a decmial
Atomic Number Vs Atomic Mass
Atomic Number is above the element, the mass is below.
Mass Number
Number of protons and neutrons combined
The atomic mass number is always
a whole number
Neutrons =
mass number - atomic number
The oxygen mass number is 16 and its atomic number is 8, what is the number of neutrons
8
Isotopes
Atoms of the same element that have different numbers of neutrons
Isotopes are
chemically alike
Isotopes have
different mass numbers
Hyphen Notation
Element-mass number
Isotopic Notation
A symbol that identifies the isotope of an element
Atomic Mass
The average mass of all the isotopes of an element
Atomic mass formula
Convert percentage back to decimal,
Multiply decimal with mass number
Add products of each isotope together
Chlorine has two common isotopes, with the mass of 35.45 amu (75.00% abundance) and 37.29 amu (25.00% abundance) What's the Atomic Mass?
35.91
What if you do not have the percentage or the atomic mass
Calculate the atomic mass of one of indium's isotopes (there are two)
If the atomic mass of indium is 114.8200 amu and one isotope of indium has a mass of 114.9041 amu and an abundance of 95.795%, whats the atomic mass?
113 amu
Atomic #
Mass #
protons + neutrons
Neutrons
mass # - atomic #
Ion
An atom or group of atoms that has a positive or negative charge.
How do ions form
When an atom gain or lose electrons
How to write an ionic charge
An ionic charge is written as a sign (positive '+' or negative '-') followed by a number.
What does the number represent in an ion
the amount of electrons gained or lost
cation
A positively charged ion
metals lose electrons to become
cations
Cations have the same name as the element that forms them but
different chemical properties
Anions
negatively charged ions
Nonmentals tend to form ions
by gaining electrons
The name of the anion is the element name
with "ide" on the end
Ions Abbreviations
Note
Flashcard