Chem 101 Chapter 11

Chem 101 Chapter 11 11.2  Wavelength is the distance between two consecutive wave peaks o Represented by a lowercase lambda  Frequency is indicated by how many wave peaks pass a certain point per given time period  Another way to think of a beam of light traveling through space is a stream of tiny packets of energy called photons. 11.4  Ground state is the lowest possible energy state of an atom  Different wavelengths of light carry different amounts of energy per photon  The energy contained in the photon corresponds to the change in energy that the atom experiences  Energy levels of hydrogen are quantized, that is, only certain values are allowed  Energy levels of all atoms are quantized 11.5  Bohr constructed a model of the hydrogen atom with quantized energy levels that agreed with hydrogen emission results  Electrons do NOT move around the nucleus in circular orbits 11.6  In the Bohr model the electron was assumed to move in circular orbits  Wave mechanical model – the electron states are described by orbitals 11.7  Orbital- the probability map of an element  1s Orbital - the orbital the hydrogen’s lowest energy state (ground state)  Principle energy levels – the discrete energy levels and are labeled with integers o Each of these levels are subdivided into sublevels  Characteristic of orbitals is that as the level number increases, the average distance of the electron in that orbital from the nucleus also increases  An orbital is the potential space for an electron 11.8  Pauli Exclusion Principle – an atomic orbital can hold a maximum of two electrons, and those two electrons must have opposite spins 11.9  The most attractive orbital to an electron is always the 1s  The 1s orbital involves the space around the nucleus that is closest to the nucleus  As n increases the orbital becomes larger o The electron on average, occupies space farther from the nucleus  Electron configuration is also called electron arrangement

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Orbital diagram, or box diagram, are represented in which orbitals are represented by boxes grouped by sublevel with small arrows indication the electrons The arrow represents an electron spinning in a particular direction Valence electrons – the electrons in the outermost (highest) principle energy level of an atom The outer most electrons, are the ones that are involved when atoms attach to each other (form bonds) The inner electrons, known as the core electrons are not involved in bonding The atoms of elements in the same group (vertical column of the periodic table) have the same number of electrons in a given type of orbital (sublevel) Elements were originally organized into groups on the periodic table on the basis of similarities in chemical properties Elements with the same valence electron arrangement show very similar chemical behavior

11.11  Metals – typically have the following physical properties: lustrous appearance, ability to change shape without breaking, and an excellent conductivity of heat and electricity  Metals tend to lose electrons to form positive ions, and nonmetals tend to gain electrons to form negative ions  Metalloids exhibit both metallic and nonmetallic behavior  As we go down the group, the metals become more likely to lose an electron  As we go down the group, the electron being removed resides, on average, farther and farther from the nucleus  The elements that can most effectively pull electrons from metals occur in the upper-right corner of the periodic table  The most chemically active metals appear in the lower left region of the periodic table  The most chemically active nonmetals appear in the upper-right- region of the periodic table  Ionization energy – is the energy required to remove an electron from an individual atom in the gas phase  Metals have a relatively low ionization energy o A relatively small amount of energy is needed to remove an electron from a typical metal  Ionization energies tend to decrease in going from the top to the bottom of the group  Nonmetals have relatively large ionization energies  Elements that appear in the lower-left region of the periodic table have the lowest ionization energy  Elements with the highest ionization energies occur in the upper-right region of the periodic table

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Atoms get larger as we go down a group and as we go from right to left in a period