Atomic Structure Flashcards
John Dalton
In 1808, suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them ATOMS
Mendelev and Meyer
In 1869, independently, they proposed the periodic table of the elements with its tendencies and components.
Balmer
In 1885, showed that energies of visible light emitted from hydrogen atom follow the equation:
E = Rh(1/2^2 - 1/nh^2)
Rh
Rydberg constant for hydrogen: 1.0097x10^7 1/m or 2.179x10-18 J
Joseph John Thompson
In 1898, found that atoms could sometimes eject a far smaller negative particle which he called an ELECTRON
What happened in 1904?
Thompson developed the Plum Pudding Model.
What is the Plum Pudding Model?
Developed by Thompson in 1904, this model stated the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron’s charge, like plums surrounded by pudding.
Ernest Rutherford
In 1910, he proposed a more detailed model of the atom that included a central nucleus. He suggested that the positive charge was all in a central nucleus holding the electrons in place by electrical attraction.
Niels Bohr
In 1913, he refined Rutherford’s idea by adding that the electrons were in orbits. With each orbit only able to contain a set number of electrons.
What are the three major parts of an atom?
Proton, neutron, electron
T/F: Each atom has different amount of protons, neutrons and electrons.
True
Describe the proton (4)
- Positively charged particles found in the atomic nucleus
- Protons were discovered by Ernest Rutherford.
- Experiments done in the late 60’s and early 70’s showed that protons are made from other particles called quarks.
- Protons are made from two “up” quarks and one “down” quark.
Describe the neutron (4)
- Uncharged particles found in the atomic nucleus.
- Neutrons were discovered by James Chadwick in 1932.
- Experiments done in the late 60’s and early 70’s showed that neutrons are made from other particles called quarks.
- Neutrons are made from one “up” quark and two “down” quarks.
Describe the electron (4)
- Negatively charged particles that surround the atom’s nucleus.
- Electrons were discovered by J.J. Thompson in 1897.
- Electrons determine properties of the atom.
- Chemical reactions involve sharing or exchanging electrons.
Describe the nucleus
- Central part of an atom.
- Composed of protons and neutrons.
- Contains most of an atom’s mass.
- The nucleus was discovered by Ernest Rutherford in 1911.
Electron mass
1/1836 mass of H atom
Describe the quark (6)
- Believed to be one of the basic building blocks of matter.
- Quarks were first discovered in experiments done in the late 60’s and early 70’s.
- Three families of quarks are known to exist. Each family contains two quarks.
- The first family consists of up and down quarks (the quarks that join together to form protons and neutrons)
- The second family consists of strange and charm quarks (only exist at high energies).
- The third family consists of top and bottom quarks (only exist at very high energies).
Describe the isotope
atoms that have the same number of protons but different number of neutrons
Give an example of an isotope
Hydrogen has three isotopes.
- Protium: 1 proton
- Deuterium: 1 proton + 1 neutron
- Tritium: 1 proton + 2 neutrons
He²₄
The superscript (2): is the atomic number, the number of protons in an atom.
The subscript (4): is the atomic mass, the number of protons and neutrons in an atom.
*In neutral species (without charge) the number of protons = number of electrons.
The three quantum numbers
n, l and ml