Chemistry: Chapter 4

Inner-shell electrons

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Photoelectric Effect

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Valence electrons

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Rules Governing Electron Configurations

1. Aufbau Principle 2. Pauli Exclusion Principle 3. Hund's Rule

Max of ___ electrons in the outer shell

8

Wave Particle Duality

A quantum entity, such as a photon or an electron travels as a wave, but arrives as a particle.

Line Spectrum

A spectrum containing radiation of only specific wavelengths

Excited State

A state in which an atom has a higher potential energy

Bohr Model & Spectral Lines

An electron can move to a higher orbit by gaining an amount of energy equal to the energy difference between the two orbits. When the electron falls back to the lower energy state the excess energy is released as a photon of light. From the wavelengths of the emitted spectral lines, Bohr was able to calculate the allowed energy levels fro hydrogen. Nor did Bohr's theory fully explain the chemical behavior of atoms.

Aufbau (Build Up) Principle

An electron occupies the lowest energy orbital that can receive it. Starting with the third main energy level (n=3), the energies of the sublevels begin to overlap.

Nobel Gasses

Are full (except neon)

Black Space

Colored lines are separated by this

Quantum Theory

Describes mathematically the wave properties of electrons and other very small particles. Solutions = wave functions The wave functions give only the probability of finding an electron at a given place around the nucleus.

Unique Spectrum

Each element has its own

Energy of a Photon

Equal to the difference in energy between the atom's two states

The Value of N

Gives the first quantum number, which indicated the main energy level occupied by the electron.

The Quantum Model

Improves upon Bohr's model because it describes the arrangement of electrons in atoms other than hydrogen. The arrangement of electrons in an atom is known as the atom's electron configuration. Electrons in atoms tend to assume arrangements that have the lowest possible energies - ground state electron configuration.

Principle Quantum Number N

Indicated the main energy level occupied by the electron. Values are positive integers As this value increases, the electron's energy and average distance from the nucleus increases.

Magnetic Quantum Number m

Indicated the oriental of an orbital around the nucleus The values allowed are m= -1.....0....+1

Angular Momentum Quantum Number l

Indicates the shape of the orbital. For each n the number of orbital shapes possible is equal to n. The values of l that are allowed are zero and all positive integers less than or equal to n-1. 1=0 s orbital 1=1 p orbital 1=2 d orbital 1=3 f orbital

Diffraction

Involves a change in direction of waves as they pass through an opening or around an obstacle in their path.

Energy State Between Atoms

Is fixed

The Heisenberg Uncertainty Principle

It is impossible to determine simultaneously both the position and velocity of an electron or any other particle.

Excited Going To Ground State

It releases the excess energy in the form of electromagnetic radiation (light). Also called releasing a photon.

Ground State

Lowest energy state of an atom

Pauli Exclusion Principle

No two electrons in the same atom can have the same set of four quantum numbers. Thus electron pairs in orbitals must be of opposite spin.

Spin Quantum Numbers

Only two possible values: +1/2 and -1/2 Indicates the two fundamental spin states of an electron in an orbital. A single orbital can hold a maximum of two electrons, which must have opposite spins.

Hund's Rule

Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin. This rule minimizes electron-electron repulsion.

Niels Bohr

Proposed a model of the hydrogen atom that linked hydrogen's electron with photon emission

Electron Beam Diffraction

Showed that the bending of an electron wave as it passes by the edge of an object, such as an atom ins a crystal, resulting in a reduction of energy in some areas and in crease of energy in others.

Quantum Numbers

Specify the properties of atomic orbitals and the properties of electrons in orbitals. The first three numbers result from the solutions to Schrodinger's Equation.

Louis de Brogile

Suggested that electrons were waves confined to the space around the nucleus. And that the waves could only exist at certain frequencies that correspond to specific energies - the quantized energies of Bohr's orbits.

Bohr Model

The electron can circle the nucleus only in allowed paths called orbits. The electron is in its ground state when it is in the orbit closest to the nucleus. The electron cannot exist in empty space between orbits. The energy of the electron is higher when it is in orbits that are farther from the nucleus (excited state).

Orbitals

The electrons do not travel around the nucleus in neat orbits, as Bohr had thought. The electrons exist in certain regions called _______ This is a 3D region around the nucleus that indicates that probable location of an electron.

White Light Through A Prism

The white light is dispersed into its component wavelengths - it contains light of all wavelengths and thus a continuous spectrum (rainbow) is produced

The Schrodinger Wave Equation

Together with the uncertainty principle, the wave equation laid the foundation for modern quantum theory.

Different Gasses In Low Pressure In A Tube

When high voltage is applied, the gases emit different colors of light

Interference

When two waves overlap to form a resultant wave of greater or lesser magnitude. As the waves bend around a obstacle, they experience this.