Chapter 2 Flashcards
Bohr atomic model
An early atomic model in which electrons were assumed to revolve around the nucleus in discreet orbitals
Pauli exclusion principle
The postulate that for an individual atom, at most two electrons, which necessarily have opposite spins, can occupy the same state
Atomic mass unit (amu)
A measure of atomic mass, 1/12 the mass of an atom of 12C
Atomic number (Z)
For a chemical element, the number of protons within the atomic nucleus
Atomic weight (A)
The weighted average of the atomic masses of an atom’s naturally occurring isotopes. Can be in amu or mass per mole of atoms
Bonding energy
The energy required to separate two atoms that are chemically bonded to each other. Can be expressed on a per-atom basis or per mole of atoms
Coulombic force
A force between charged particles such as ions; the force is attractive when the particles are of opposite charge
Covalent bond
A primary interatomic bond that is formed by the sharing of electrons between neighboring atoms that have similar electronegativities. Normally s and p orbitals are involved. Have variable bond energies, are directional, and are found in semiconductors, ceramics, and polymer chains.
Dipole (electric)
A pair of equal and opposite electrical charges separated by a small distance
Electron configuration
For an atom, the manner in which possible electron states are filled with electrons
Electron state
One set of discrete, quantized energies that are allowed for electrons. In the atomic case, each state is specified by four atomic numbers
Electronegative
For an atom, having the tendency to accept valence electrons. Also used to describe nonmetallic elements
Electropositive
For an atom, having the tendency to release valence electrons. Also used to describe metallic elements
Ground state
A normally filled electron energy state from which an electron excitation may occur
Hydrogen bond
A strong secondary interatomic bond that exists between a bound hydrogen atom (its unscreened proton) and the electrons of adjacent atoms
Ionic bond
A coulombic interatomic bond that exists between two adjacent and oppositely charged ions that requires the transfer of electrons and a large difference in electronegativity. They have large bond energy, are nondirectional, and are found in ceramics.
Isotope
Atoms of the same element that have different atomic masses
Metallic bond
A primary interatomic bond involving the nondirectional sharing of nonlocalized valence electrons (sea of electrons) that are mutually shared by all the atoms in the metallic solid. Have variable bond energies, are nondirectional, and are found in metals.
Mole
The quantity of a substance corresponding to 6.022 * 10^23 atoms or molecules
Periodic table
The arrangement of the chemical elements with increasing atomic number according to the periodic variation in electron structure. Nonmetallic elements are positioned to the far right-hand side of the table
Polar molecule
A molecule in which there exists a permanent electric dipole moment by virtue of the asymmetrical distribution of positively and negatively charged regions
Primary bonds
Interatomic bonds that are relatively strong and for which bonding energies are relatively large. Types: ionic, covalent, metallic
Quantum mechanics
A branch of physics that deals with atomic and subatomic systems; it allows only discrete values of energy. By contrast, for classical mechanics, continuous energy values are permissible
Quantum number
A set of four numbers, the values of which are used to label possible electron states. Three of the quantum numbers are integers that specify the size (n), shape (l), and spatial orientation (ml) of an electron’s probability density; the fourth number designates spin orientation (ms).
