History of Atomic Structure
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The Greeks named the particles "atomos" which means. . .
Atomos means indivisible
One part of Dalton's Atomic Theory is that all atoms are indivisible and indestructable. Is that true today?
No. Atoms are divided into subatomic particles And we have been able to split the atom.
One part of Dalton's Atomic Theory is that all atoms of an elment are identical. Is that true today?
No. They differ in mass (isotopes) and charge (ions)
One part of Dalton's Atomic Theory is that atoms of a specific element are different from another element. Is that true today?
One part of Dalton's Atomic Theory is that atoms combine in simple whole # ratios. Is that true today?
Yes - The Law of Definite Proportions
What is the ray of a cathode ray tube made of?
Cathode ray tube has a beam of electrons
JJ Thomson is famous for what discovery?
JJ Thomson identified the electron
Describe Thomson's model of the atom
Plum pudding - a sphere of positive charge with negative charges embeded
Radioactivity is the spontaneous decay of the nucleus with the emission of energy/particles
Who is credited with the "discovery" of radioactivity?
Marie Curie won the Nobel prize for the discovery of what elements?
Radium (Ra) and Polonium (Po)
What did Ernest Rutherford name the positive radioactive particles?
Rutherford named the positive radioactive particles alpha particles.
When Rutherford shot alpha particles at piece of gold foil, what was observed?
Rutherford observed that most of the alpha particles went straight through and some were deflected
Rutherford observed that most of the alpha particles went straight through the gold foil. What does that tell us about the structure of an atom?
It tells us the atom is mostly empty space.
Some alpha particles were deflected by the gold foil. What does that tell us about the structure of the atom?
Deflections tells us that there is a small, dense, positive charged nucleus.
Describe the Bohr model of an atom in terms of the location of the electrons.
Bohr model has the electrons at specific distances from the nucleus (like rings around the nucleus)
What is a principle quantum number?
Principle quantum number is the electron shell number.
To what does the quantum in "principle quantum number" refer?
quantum refers to a certain amount of energy associated with each electron shell
What is another name for electron shell?
Another name for electron shell is energy level.
Where are the electrons located in the wave mechanical model of an atom?
The electrons located in an electron cloud outside the nucleus in the wave mechanical model.
What is the charge of the nucleus of an atom? What is the reason for this charge?
The nucleus has a positive charge due to the positive protons and neutral neutrons located there.
What is the charge of an atom? What is the reason for this charge?
The charge of an atom is neutral. This is because the number of + protons equals the number of - electrons.
What identifies an atom on the periodic table?
The number of protons identifies an atom, so the atomic number on the periodic table.
An ion is an atom with a charge due to a gain or loss of electrons.
If Carbon lost 4 electrons, how would one write the symbol for that ion?
Using the periodic table, how do you determine the number of neutrons in an atom?
Subtract the atomic number from the atomic mass.
How many electrons in sulfide ion, S -2 ?
S -2 has 18 electrons.
Isotope is an atom of an element with a different atomic mass.
Why do isotopes of an element have different atomic masses?
Isotopes have a different number of neutrons.
How many neutrons in each of these isotopes:
35 S 222Rn
- 35 S has 19 neutrons (35-16 = 19)
- 222Rn has 136 neutrons (222-86 =136)
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