Unit 4: Electrons and the Periodic Table

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form of energy that exhibits wave-like behavior as it travels through space
crest (parts of a wave)
top of a wave
trough (parts of a wave)
bottom of a wave
amplitude (parts of a wave)
height of a crest or depth of a trough
wavelength (parts of a wave)
distance of a wave (crest to crest or trough to trough); units = m; variable = λ
equilibrium (parts of a wave)
natural or “rest” position
frequency
# of wave cycles to pass a given point; units = Hz or 1/s; variable = f
velocity
how fast a wave moves from one given point to another; = speed of light (c) = 3.0 x 10⁸ m/s; units = m/a; variable = c
c= λf
speed = wavelength * frequency; wavelength (λ) and frequency (f) inversely related
electromagnetic spectrum
illustrates all forms of electromagnetic radiation
Planck
German physicist; energy changes only in small discrete units, called quantums of energy
E=hf
energy = planck’s constant * frequency; frequency (f) and energy (E) directly related
Planck's constant
6.626x10-34 J/s; variable = h
Joules
unit of energy; unit = J; variable = E
gamma
type of electromagnetic radiation; highest amount of energy; can do most harm
violet
visible color; w/ highest energy
photoelectric effect
electrons emitted from matter bc of absorption of energy from electromagnetic radiation
Einstein (discovery)
light has both wave AND particle properties; beam of light behaves as a wave
atomic emission spectrum
every element emits light when an electric discharge is passed through its gas phase; atoms absorb energy, then release energy through light
principal energy levels
region around the nucleus where the electrons are likely to be moving; more levels → more dis b/w electron + nucleus; contains sublevels
energy sublevels
according to the shapes of the atom’s orbitals
s sublevel
sphere; 1 orbital, 2 electrons
p sublevel
dumbbell; 3 orbital, 6 electrons
d sublevel
clover; 5 orbital, 10 electrons
f sublevel
daisy; 7 orbital, 14 electrons
atomic orbitals
electron probability cloud of an atom’s electrons; may contain at most 2 electrons
electron configuration
shorthand method of writing quantum numbers to represent the arrangement of electrons in atom; all superscripts added = atomic number = # of electrons; last part shows location on periodic table
Aufbau Principle
electrons enter orbitals of lowest energy first (ex: 1s2s2p3s3p4s3d4p; 1s is first)
Pauli Exclusion Principle
1 or 2 electrons per orbital; must spin in opposite directions (opposite spins hold e- in orbital by magnetic attraction)
Hund’s Rule
orbitals of equal energy must EACH have 1 electron with the same spin before any orbital is occupied by a 2nd electron (empty bus seat rule)
electron configuration (coefficient)
represents the energy level
electron configuration (small letter)
represents the sublevel
electron configuration (exponent)
represents the # of electrons
orbital diagrams
visual representation of the electron configuration; each orbital > horizontal line; each line labeled with energy level and sublevel; one electron = one arrow; arrows point opposite directions; include empty orbitals of a sublevel that contains an electron
atomic states
ground or excited state; e- moves; arrangement of the electrons in an atom
ground state
state of lowest energy for an atom (preferred state bc stable); into state releases energy (photon emitted); correct order
excited state
state in which atoms have higher potential energy; into state requires energy; causes electrons to move to higher energy levels
excited state (how to)
noble gas shortcut
electron configuration; starts at noble gas before element
groups (periodic table)
numbers 1-18 (ones column represents # of valence electrons (electrons in the outermost energy level)); columns; similar physical and chemical properties
periods (periodic table)
numbers 1-7; rows; number of energy levels
blocks of elements (periodic table)
designated by s, p, d, f
zig-zag line (periodic table)
separates metals from nonmetals; metals on left, nonmetals on right
metalloids
along zig-zag line (except aluminum (al)); mostly brittle solids; mixed properties of metals + nonmetals
alkali metals
group 1; except hydrogen; will give up 1 e- to form +1 ion; usually stored under oil bc reacts with water; physical property: soft, silvery metals used in medicine and soaps; most reactive metals
alkaline earth metals
group 2; will give up 2 e- to form the +2 ion; less reactive than group 1 (not as easy to give up 2 e-)
halogens
group 17; will take 1 e- to form the -1 ion; most reactive nonmetals; v close to full valence shell (outer energy level)
noble gasses
group 18; except helium; only needs 2 e- to be full; least reactive group because they have full valence shell (outer energy level)
inner transition elements
metallic elements (outermost f-block); lanthanides (4f), silvery with high melting points; actinides (5f) series, radioactive (>82)
ion
atom (or group of combined atoms) with charge bc of loss or gain of e-
oxidation number
charge of an ion
octet rule
atoms gain or lose electrons to get full valence shell (8 electrons in outer energy level); gets atom the electron configuration of noble gas
distance between nuclei; increases left, down; Adding electrons to higher energy levels; increases the # of energy levels
cesium
largest atomic radius + most reactive metal
distance from the center of the nucleus to the outer edge of the ion
lose electrons; protons > electrons, protons have more pulling power; results in smaller radius
gain electrons; Electrons > protons, more repulsion between electrons; results in a larger radius
ionization energy (IE)
energy required to remove the outermost e- from an atom (kJ/mol); to get outer energy level closer to an octet; increases up, right; electrons further from nucleus = easier to take
helium
highest IE
electronegativity (EN)
measure of atom's ability to grab e- from another atom; increases up, right; elements at top of group have e- closely held to the nucleus
fluorine
most electronegative element; most reactive nonmetal
reactivity
refers to how likely an atom is to react with others; depends on how easily electrons can be removed (low IE) + how easily electrons can be gained (high EN)
noble gasses
least reactive group
lanthanides
inner transition element; 4f; silvery with high melting points
actinides