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# Chemistry Midterm 2006

## Terms

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Kinetic Energy
energy in motion
SI unit of energy
Joule
SI unit of heat
kelvin
What's an isotope and how does it affect atomic mass?
An isotope is an atom with the same number of protons but a different number of neutrons. It affects atomic mass because different isotopes of the same element have different numbers of neutrons, which makes it different sizes.
Calculate the number of protons, neutrons, and electrons in an atom, given its atoc number and atomic mass.
atomic number = protons. If it is an atom, not an ion or an isotope, it has an equal amount of electrons. Neutrons = Atomic Mass â€“ Atomic Number
What is an isotope?
same # of protons, different # of electrons
Dalton's theories
All elements are composed of atoms
All atoms of a certain element are identical, but unique from other elements atoms.
Atoms are neither created nor destroyed
A given compound always has the same ratio of kinds of atoms.
What was Thomson's contribution to the atomic model?
he discovered electrons through the cathode ray tube.
What was Rutherford's contribution to the atomic model?
He discovered radiation
What was Millikan's contribution to the atomic model?
He created the oil-drop experiment, through which he calculated the mass of an atom
What is Planck's Theory of Energy Quanta
There is a fundamental restriction on the amount of energy that an object emits or absorbs. Each of those peices of energy is called a quanta.
Compare and Contrast the Bohr model with the quantum-mechanical model of the atom. Explain how electrons are described in the two models
According to the quantum mechanical model, electrons have no precise orbits. Instead, their motion cano bly be described by the probability of finding them in certain regions surrounding the nucleus. In the Bohr model ,there are specific orbitals in which the electrons move.
State the three ground principles by which we can predict the locations of the electrons in the ground state of an atom
The Aufbau Principle: Add electrons to the lowest levels until all have been accounted for.
The Pauli Exclusion Principle: An orbital can have a max of 2 electrons, and those 2 electrons must have opposite spins.
Hund's Rule: Fill up each orbital before moving onto the others.
How are different colors in neon signs and fireworks produced.
As the excited electrons return to lower orbitals, they emit light energy in those colors.
Electron Affinity
the energy change that occurs when it gains an extra electron
Electronegativity
An atom's ability to attract electrons in a chemical bond
Where are metals, transition metals, nonmetals, and semimetals found in the periodic table?
metals: left
nonmetals: right
transition metals: middle
semimetals: right, between nonmetals and metals
What is the order of orbitals?
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f

and make a swervy line

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