Electron-Configuration Notation

download report

Transcript Electron-Configuration Notation

Ch.4
Electrons
Energy as Waves
• Light (one form of energy) travels
through space in a wavelike behavior
• Other forms of energy also have
wave characteristics
(electromagnetic spectrum) p. 98
• The more energy, the faster the wave
moves, the shorter the wavelength –
p.98
Electromagnetic Spectrum
Wavelength & Frequency
Electrons as Waves
• Each element has a set number of
subatomic particles
• Those particles (electrons) can be
excited by extra energy and emit a
color
• Each element has a different set
number of electrons thus, having a
different color emitted
• This color is an identifying
characteristic of the element p.101
Table 2 p.110
Electron Emission Spectrum
Background Information
• De Broglie set out to prove that
electrons acted as particles and
waves in 1924 – found that electrons
existed as waves in a small space
which is also like a particle
• Heisenberg made a conclusion in
1927, that it is impossible to
calculate the position and velocity of
an electron at the same time
Additional Background
• Schrodinger developed the quantum
theory and four quantum numbers (that
are letters) to explain his theory –n,l,m,s
• Summary of quantum numbers –Table 2 - p.110
• Remember: s – holds 2ep – holds 6ed – holds 10ef – holds 14eorbitals can only hold 2e- each, each
sublevel has an orbital count of half its e-
Electron Configuration
• A systematic way of placing all of the
electrons of an atom into their energy
level, sublevel, and correct spin
• Connects to the periodic table into
repeating trends and characteristics
of metals, nonmetals, and metalloids
Rules to Follow
• Aufbau principle – an electron
occupies the lowest-energy level first
• Pauli exclusion principle – two
electrons in the same orbital must
have opposite spins
• Hund’s rule – all electrons must
singly occupy orbitals of the same
spin before adding another electron
of opposite spin – p.112
Orbital Notation
• Notates electrons represented as arrows in
opposite spins in its orbital that is
represented by an underline or a box
• Let’s practice!!
p.113
(1 & 2)
• Electron-Configuration Notation –
eliminates the arrows and lines and
represents the electrons by superscripts
• Let’s practice!!
p.121 (1-5)
Orbital Diagrams
Noble Gas Notation
• Used as a short hand method of
finding the electron configuration
• Used for higher atomic numbers
• Place the noble gas before the atom
in question in brackets
• Start at the next energy level and
add electrons from the noble to the
total amount of electrons as normal
• Example: [Kr]5s1
Lewis Dot Diagram
• Once the valence electrons are
established, either by electron
configuration or position of periodic
table, only those electrons are used in
bonding.
• Those electrons are notated by
representing them as dots around the
element symbol
• Example: Ar has 18 electrons what
does the electron dot diagram look
like?
Oxidation Numbers p.232
• Basically, charges depicting the number of
electrons that are lost or gained
• Can be determined by the number of
electrons needed to fill orbitals to make
them complete or the number of electrons
transferred to get to a level that has full
orbitals
• Because all groups on the periodic table
have the same valence electrons, the
position of the element tells the oxidation
number
• Example: H+1 or H1+
Ch. 5 Periodic Law
History of Periodic Table
• Credit for the first periodic table goes to
Russian scientist Dmitri Mendeleev that
was published in 1869.
• Mendeleev arranged the periodic table in
order of increasing atomic mass.
• In 1911, Henry Moseley rearranged the
periodic table in order of increasing atomic
numbers which made more of a
connection. Also known for periodic law.
Some Elements
Mendeleev Predicted
Electron Configuration & The
Periodic Table (pp. 138-139)
• The periodic table has been divided into 4 blocks that
represent the s,p,d, & f sublevels of electron
configuration.
• The ending configuration (last part of configuration) is
used to locate the desired element.
• One is added to the ending configuration for d-block
to find its location on the periodic table.
• Two is added to the ending configuration for f-block
to find its location on the periodic table.
Periodic Trends Definitions
• Atomic Radius – def: one-half the distance
between the nuclei of two identical atoms
that are bonded together
• Electronegativity – def: a measure of the
ability of an atom in a chemical compound to
attract electrons from another atom in the
compound
• Ionization energy – def: the energy
required to remove one electron from a
neutral atom of an element
Periodic Trends