Atomic Theory And Models Flashcards
What is the Plum Pudding model?
Atoms are made mostly out of positively charged material, like dough in a bun. The negatively charged electrons are found inside the positive dough
Who created the Plum Pudding model?
JJ Thomson
When did Thomson’s introduce his theory?
1897
What did Democritus contribute to the atomic theory?
He said:
Matter is formed of small pieces that could not be cut into smaller parts called atomos meaning uncuttable
When did Democritus introduce his theory?
430 BC
What information did John Dalton contribute to the atomic theory?
1) Atoms are tiny,invisible particles
2) Atoms of one element are all the same
3) Atoms of different elements are different
4) Compounds form by combining atoms
When did John Dalton introduce his theory?
1808
The positively charged particle in an atom
Proton
What is a proton?
The positively charged particles in the nucleus
Atom model
A representation of an Atom (a picture of what the atomic theories explain)
Atom
The smallest particle in which an element can be divided and still be the same substance
John Dalton
British Chemist who developed his atomic theory gathered from observations gathered during his experiment.
Electron
The negatively charged particles in an atom that are involved in the formation of chemical bonds
Particle
A tiny piece or part
Nucleus
The tiny extremely dense positively charged region in the center of an atom, made of protons and neutrons
Bohr Model
The model of the atom that states that electrons move around the center of the atom’s nucleus in fixed orbit; also called the planetary model
Ernest Rutherford
Scientist Who stated that the atom was mostly empty space in at the center was a small dense positively charged nucleus
Neils Bohr
Danish Scientist who suggested that electrons travel around the nucleus in fixed paths
Fixed orbit
To revolve around an object in a fixed path
Neutron
The particles of the nucleus that have no charge
Quarks
The subatomic particles that make up protons, electrons, and neutrons.
Subatomic particle
Any particles that are smaller than an atom
Electron cloud
The regions inside an atom where electrons are likely to be found
Mass number
The sum of the protons and neutrons in an atom
John Thomson
British chemist whose experiments with the cathode-ray tube led to the discovery of electrons
Atomic mass unit (amu)
The SI unit used to express the masses of particles in an atom
Atomic number
The number of protons in the nucleus of an atom
Atomic mass
The weighted average masses of all the naturally occurring isotopes of an element
Chemical symbol
A shorthand way to write the name of an element
Isotope
Atoms with the same number of protons but hav different numbers of neutrons
Periodic table
A table of elements in order by increasing atomic mass
Energy level
A region of an atom in which electrons if the same energy are likely to be found
Why do scientists use models?
To help explain the structure of an atom
What things makes an atomic model useful?
It must support all the information that is known about matter and the behavior of atoms
_________’s model was a simple sphere
John Dalton’s
________ join with other _______ to form new substances
Atoms;atoms
Who discovered the electron?
John Thomson
When was Ernest Rutherford’s atomic theory proposed?
1911
Who discovered the nucleus of an atom
Rutherford
Who said hat electrons travel in fixed orbits?
Neils Bohr
What is Niels Bohr’s model called?
Bohr model / planetary model
What is the model we currently follow today?
Electron Cloud Model / Quantum Mechanics model
What’s the difference between the electron cloud model and Bohr’s model?
Bohr’s model showed electrons traveling in fixed paths, electron cloud had electrons scattered throughout randomly with no predicted pattern
When did James Chadwick discover the neutron?
1932
In 1932, _______ _______________ discovered the neutron in the center of an atom
James Chadwick
Where are the electrons located in an atom?
The electron cloud
What is atomic mass?
The weighted average masses of all the naturally occurring isotopes of an element
What charge does a proton have?
Positive
What charge does a neutron have?
Neutral / no charge
What charge does an electron have?
Negative
What was JJ Thomson’s model of the atom called?
The Plum Pudding Model
How many neutrons does a titanium atom have if:
The atomic number is 22
The atomic mass is 48
26
Which subatomic particles have the most mass?
Protons and neutrons
Where are the protons and neutrons located?
The nucleus
Why does and atom have a neutral charge?
Because a normal atom has the same amount of protons as electrons which cancel each other out
How are the numbers of protons determined in an element
The atomic number
How do you determine the number of neutrons in an atom?
You subtract the atomic number from the atomic mass
What’s the weakest force in the atom?
Gravity
What is the strongest force in an atom?
Strong force
What are the four forces in an atom?
1) Gravity
2) Electromagnetic Force
3) Strong Force
4) Weak Force
Organize the forces in an atom from strongest to weakest
1) Strong Force
2) Electromagnetic Force
3) Weak Force
4) Gravity
