Addison Wesley Chemistry Chapter 12: Electrons in Atoms

Thomson Model of the Atom

Atoms are made of positively charged protons w/negatively charged electrons spread throughout. Also called the "Plum Pudding Model"

Rutherford Model of the Atom

The atom has a small, dense, positively charged nucleus, made of protons and neutrons, that is surrounded by negatively charged electrons

Bohr Model of the Atom

The electrons of an atom orbit the nucleus at set distances with fixed energy, thereby preventing the electrons from collapsing into the nucleus

Quantum Mechanical Model

The primarily mathematical description of atoms that states that atoms do not have definite shapes and electrons do not have precise orbits

Energy Level

A region around the nucleus where the electrons are likely to be moving

Quantum

The amount of energy needed to move an electron from its present energy level to the next higher one

Energy Levels Decrease As...

The electrons get closer to the nucleus

The Higher the Energy Level....

The easier it is for the electron to escape from the atom

Energy Sublevels

The energy levels contained within a principal energy level, like books in a bookcase

Atomic Orbitals

The regions around the nucleus within which the electrons have the highest probability of being found. Located within energy sublevels

S Orbital

Spherical, 2 electrons

P Orbitals

Dumbell shaped, exist in 3 dimensions (px, py, pz); 6 electrons

D Orbitals

10 electrons

F Orbitals

14 electrons

Electron Configurations

The ways in which electrons are arranged in various orbitals around the nuclei of atoms

Aufbau Principle

Electrons enter orbitals of lowest energy level first

Pauli Exclusion Principle

An atomic orbital can hold a maximum of two electrons, and those two electrons must have opposite spins

Hund's Rule

When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins

Electron Config Exceptions

Chromium and copper atoms

Electromagnetic Radiation

A form of energy that exhibits wavelike behavior as it travels through space; includes radio waves, microwaves, visible light, infrared and ultraviolet light, x-rays, and gamma rays

Amplitude

The height of a wave from the origin to a crest, or from the origin to a trough

Wavelength (Lambda)

The distance between crests of waves, such as those of the electromagnetic spectrum.

Frequency (v, the Greek letter nu)

The number of wave cycles to pass a given point per unit of time

Relationship Between Wavelength and Frequency

Inversely proportional;

as one increases, the other decreases

Hertz (Hz)

SI unit of frequency, equal to one cycle per second

Spectrum

Colored band produced when a beam of light passes through a prism

Atomic Emission Spectrum

The pattern formed by passing the light emitted by an element through a prism. Emission spectrographs must be utilized in order to see the pattern

The Energy of a Quantum Equals...

Planck's constant * frequency

Planck's Constant

a number used to calculate the radiant energy (E) absorbed or emitted by a body based on the frequency of radiation; 6.6262 * 10^-34

Quantum Concept

Matter can gain or lose energy only in small specific amounts called quanta

Photons

Quanta of light

Photoelectric Effect

The emission of photoelectrons from a metal surface when electromagnetic radiation above a threshold frequency is incident on the metal

Increasing the Intensity of the Electromagnetic Radiation....

Increases the amount of photons striking the metal

Increasing the Frequency of the Electromagnetic Radiation...

Increases the speed of the ejected photoelectron

Ground State

The lowest energy state of an atom

Spectroscopy

The study of the properties of light that depend on wavelength.

De Broglie's Equation

Wavelength = Planck's constant/mass of particle * velocity of particle

De Broglie's Theory

All matter exhibits wavelike motions

Quantum Mechanics

Describes the motions of subatomic particles and atoms as waves and how these particles gain or lose energy in packets called quanta

Heisenberg Uncertainty Principle

It is impossible to know exactly both the velocity and the position of a particle at the same time