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Flashcards in Atomic Structure Test Deck (24)
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What was Democritus theory of matter

Described matter as being composed of tiny particles that were indivisible


What was aristotiles theory of matter

Did not except the idea of atoms


What was daltons atomic theory

All matter composed of small particles called atoms
Atoms of a given element are identical
Atoms cannot be created, divided, or destroyed
Atoms combine in whole number ratios
Atoms are separated, combined, or rearranged in chemical reactions


What parts of daltons theory were true

All matter is composed of small particles called atoms
Atoms combine in whole number ratios


What does daltons theory of an atom look like

A black sphere


What was thomsons atomic theory?

Discovered electrons
Described atoms as being composed of electrons embedded in a mass of positive charge
Is called plum pudding model (or chocolate chip cookie model)
Looks like chocolate chip cookie


What was rutherfords atomic theory

Discovered the nucleus of an atom
Concluded that positive particles are centrally located in atoms
Rutherfords model is positive in center , electrons surrounding itp
Protons and neutrons (not discovered yet) huge compared to electrons


What was Chadwick's atomic theory

Discovered neutrons
Chadwick's atom protons and neutrons surrounded by electrons


What was bohrs atomic theory

Described the organization of electrons in atoms
Identified quantized energy levels as distinct circular paths followed by electrons in atoms
Is called the planetary model
Model looks like protons and neutrons in center, surrounded by electrons in energy levels


What's the modern atomic theory

Describes electron movement as wavelike and in clouds instead of distinct circular paths


What's the Heisenberg uncertainty principle

The exact position and exact speed of an electron can never be known so the same time
Heisenburgs model is protons and neutrons in center, waves where you don't know exactly where electrons are


How do atoms differ

Atomic number
Mass number


What's atomic number

The number of protons in the nucleus of an atom
Is unique for each element


What's the mass number

The number of protons and neutrons in an atomic nucleus
Not on periodic chart
Carbon-12 6pt 6nt
Carbon-13 6pt 7nt


What are isotopes

Atoms of a particular element that have different numbers of neutrons in their nuclei (same # of protons)
Neutrons have to do with mass, not charge


What are subatomic particles

Particles within the atom, so protons, neutrons, electrons


How do you determine the number of protons (and electrons in a neutral atom)

Look at the atomic number on the periodic chart
Positive charge cancels out negative charge , do neutral atoms have the same number of protons and electrons because charges cancel each other out


How do you determine the number of neutrons

Subtract atomic number from mass number
Number of neutrons=mass number-atomic number


Masses of individual atoms are



Atomic mass unit is _ the mass of a _ atom , equivalent to the mass of _ and _

1/12, carbon -12 atom, 1 pt and 1 nt


Where the average atomic mass measurement

Amu (atomic mass unit)


What's average atomic mass, how do you find the most abundant isotope

The weighted average mass of all isotopes of an element
Most abundant isotopes round AAM


How do you calculate average atomic mass

Multiply the atomic mass of each isotope by thr percent abundance, do for each isotope
Convert percentages to decimal numbers before multipyling
Ex 25%= 0.25
2.6%= 0.026
Add the number of results from step 1 together to get final answer


What is an atom?

The smallest particle of matter that cannot be further broken down
An atom isn't made of one thing, but if you separate atoms, the piece of matter isn't the same