Chapter 2 - Chemistry Review Flashcards
charge magnitude
1.602e-19 C (positive for protons, negative for electrons)
atomic number
“Z” number of protons in the nucleus. For an electrically neutral or complete atom also equals the number of electrons.
atomic mass
“A” the sum of the masses of protons and neutrons within the nucleus.
isotope
the 2+ atomic masses of an atom
atomic weight
the weighted average of the atomic masses of the atom’s naturally occurring isotopes
atomic mass unit
“amu” may be used to compute atomic weight. 1 amu = 1/12 of the atomic mass of carbon 12
mole (Avogadro’s number)
6.022e23 atoms or molecules
1amu/atom =
1 g/mol
quantum mechanics
A set of principles and laws that govern systems of atomic and subatomic entities.
Bohr atomic model
Early attempt where electrons are assumed to revolve around the nucleus in circles and they make quantized energy levels.
wave-mechanical model
electron is considered to exhibit both wave-like and particle-like characteristics, characterized by quantum numbers
quantum numbers
size, shape, spacial orientation, principal quantum number
principal quantum number
K, L, M, N : related to the distance of an electron from the nucleus
second quantum number “l”
s, p, d, f : signifies the subshell, related to the shape of the electron subshell
third quantum number “m(l)”
1, 3, 5, 7 : number of energy states for each subshell
fourth quantum number “m(s)”
+1/2, -1/2 : the spin moment
electron states
values of energy that are permitted for electrons
Pauli exclusion principle
Stipulates that each electron state can hold no more than two electrons (having opposite spins)
ground state
when all the electrons occupy the lowest possible energies
electron configuration
the manner in which electron states are occupied
valence electrons
the electrons which occupy the outermost shell
stable electron configurations
when the states in the outermost or valence electron shell are completely filled (inert or noble gases)
periods
horizontal rows
group
columns, have similar valence electron structures as well as chemical and physical properties
inert gases
Group 0
halogens
Group VIIA
alkali and alkaline earth metals
Groups IA, IIA
transition metals
Groups IIIB - IIB
electropositive elements
elements under the metal classification, capable of giving up their few valence electrons to become positively charged ions
electronegative elements
right-hand side of the table, readily accept electrons to form negatively charged ions
electronegativity trend
increases in moving from left to right and from bottom to top
Force-potential energy relationship for two atoms
E = ∫ F*dr E(N) = ∫∞r F(A)*dr + ∫∞r F(R)*dr E(N) = E(A) + E(R)
bonding energy
E(0) the energy at the minimum point of the net energy curve
types of primary or chemical bonds (3)
ionic, covalent, metallic
ionic bonding
primary bond, always found in compounds of metallic and nonmetallic elements, steal electrons, non-directional, often ceramics, hard and brittle, insulative
coulombic force
positive and negative ions attract one another, ionic bonding
attractive energy - interatomic separation relationship
E(A) = -A/r
repulsive energy - interatomic separation relationship
E(R) = B/r^n
non-directional
magnitude of the bond is equal in all directions
covalent bonding
primary bond, often nonmetallic elemental molecules or elemental solids, share electrons, often polymeric materials
metallic bonding
primary bond, electrons “float”, good conductors
ion cores
metallic bonds, the non valence electrons and atomic nuclei
secondary bonds, Van der Waals bonds
weak in comparison to primary or chemical bonds, arise from dipoles (positive end of one dipole and negative region of adjacent attract)
hydrogen bonding
secondary bond, when hydrogen is covalent bonded to F, O or N so the other side is a essentially a positively charged bare proton
polar molecule
when permanent dipole moment exist by virtue of asymmetry
