Gen Chem 1 Quiz 7

What are the possible values of the magnetic quantum number m(l)? What does the magnetic quantum number determine?

-l to +l. Specifies the orientation of the orbital.

What are the possible values of the angular momentum quantum number l? What does the angular momentum quantum number determine?

0,1,2,3, and so on. Determines the shape of the orbital. 0 to (n-1)

Who is credited with arranging the periodic table? How are the elements arranged in the modern periodic table?

Mendeleev. Based on periodic law, when elements are arranged in order of increasing mass, the properties recur periodically. Mass increases left to right and elements with similar properties fell in the same columns.

Periodic properties?

Predictable based on the element's position within the periodic table.

Explain the contributions of Meyer and Moseley to the periodic table.

Meyer proposed an organization of the know elements based on periodic properties. Meseley listed elements according to atomic number rather than mass.

What is an orbital diagram?

Symbolizes the electron as an arrow in a box that represents the orbital.

An electron behaves in ways that are at least partially indeterminate. Explain.

The indeterminate behavior of an electron means that under identical conditions, the electron does not have the same trajectory and does not "land" in the same spot each time.

Trajectory? What kind of information do you need to predict the trajectory of a particle?

A path that is determined by the particle's velocity, its position, and the forces acting on it.

What is a quantum-mechanical orbital?

A probability distribution map showing where the electron is likely to be found.

What is a probability distribution map?

A statistical map that shows where an electron is likely to be found under a given set of conditions.

Why does the uncertainty principle make it impossible to predict a trajectory for the electron?

Because the uncertainty principle says that you cannot know both the position and velocity of the electron simultaneously, you cannot predict trajectory.

Why is electron spin important when writing electron configurations? Pauli exclusion principle.

No two electrons in an atom can have the same four quantum numbers. Because 2 electrons occupying the same orbital have three identical quantum numbers, they must have different spin numbers.

Penetration? How does penetration of an orbital into the region occupied by core electrons affect the energy of an electron in that orbital?

Occurs when an electron penetrates the electron cloud of the 1s orbital and experiences the charge of the nucleus more fully.

What is shielding? Which electrons tend to do the most shielding?

Occurs when one electron is blocked form the full effects of the nuclear charge so that the electron experiences only a part of the nuclear charge. It is the inner core electrons.

Explain the difference between a plot showing the probability density for an orbital and one showing the radical distribution function.

Probability density: the probability per unit of volume of finding the electron within a thin spherical shell at a distance r from the nucleus. Radical distribution has a value of zero at the nucleus.

What is electron configuration?

Shows the particular orbitals that are occupied by electrons in an atom.

Why are atoms usually displayed as spheres when most orbitals are not spherically shaped?

Usually drawn as spheres because most atoms contain many electrons occupying a number of different orbitals. The shape of an atom is obtained by superimposing all of its orbitals.

List the four different sublevels. Determine the max number of electrons that can exist in each level.

sublevel s can hold 2 electrons. sub level p can hold 6 electrons. d can hold 10. f can hold 14.

What are the possible values of the principal quantum number n? What does the principal quantum number determine?

1,2,3 and so on. Determines the overall size and energy of an orbital.

What are degenerate orbitals? How are degenerate orbitals occupied?

Degenerate orbitals are orbitals of the same energy. Hund's rule: when filling degenerate orbitals, electrons fill them single first with parallel spins.

Newton's laws of motion are deterministic. Explain

Deterministic means that the present determines the future. That means that under identical conditions, identical results will occur.

Explain the contributions of Johann Dobereiner and John Newlands to the organization of elements.

Dobereiner attempted to organize table into triads. Newlands organized into octaves, the properties of every eighth element were similar.

For each solution to the Schrodinger equation, what can be precisely specified: the electron's energy or its position? Explain

Electron has a well-defined energy, but not a well-defined position. Electron's position is described in terms of an orbital.

Explain Heisenberg's uncertainty principle. What paradox is at least partially solved by the uncertainty principle?

The product of the change in x and m(change in velocity) must be greater than a finite number. The more accurately you know the position of an electron, the less you can know if its velocity. An electron is observed as either a particle or a wave, but never both at once.

What observations led to the periodic law? What theory explains the underlying reasons for the periodic law?

The properties of elements recur and certain elements have similar properties. Quantum- mechanical theory explains periodic law.

Which periodic property is particularly important to nerve signal transmissions?

The relative size of the sodium and potassium ions. The pumps within membranes are so sensitive to size that they can selectively allow only one or the other to pass.

Why are the sub levels within a principal level split into different energy for multi electron atoms but not for the hydrogen atom?

because of Penetration of the outer outer electrons into the region of the core electrons. The sub levels in H are not split because they are empty.