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Electron Arrangement. Unit 3. NC Essential Standards. Chm.1.1.2 • Analyze diagrams related to the Bohr model of the hydrogen atom in terms of allowed, discrete energy levels in the emission spectrum. • Describe the electron cloud of the atom in terms of a probability model. - PowerPoint PPT Presentation
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Electron Arrangement
Unit 3
NC Essential StandardsChm.1.1.2 • Analyze diagrams related to the Bohr model of the hydrogen atom in terms of allowed, discrete energy levels in the emission spectrum. • Describe the electron cloud of the atom in terms of a probability model. • Relate the electron configurations of atoms to the Bohr and electron cloud models. Chm.1.1.3 • Understand that energy exists in discrete units called quantaDescribe the concept of ground and excited states of electrons in an atom1. When an electron gains an amount of energy equivalent to the energy difference, it moves from its ground state to a higher energy level. 2. When the electron moves to a lower energy level, it releases an amount of energy equal to the energy difference in these levels as electromagnetic radiation (emissions spectrum). • Articulate that this electromagnetic radiation is given off as photons. • Understand the inverse relationship between wavelength and frequency, and the direct relationship between energy and frequency. • Use the “Bohr Model for Hydrogen Atom” and “Electromagnetic Spectrum” diagrams from the Reference Tables to relate color, frequency, and wavelength of the light emitted to the energy of the photon. • Explain that Niels Bohr produced a model of the hydrogen atom based on experimental observations. This model indicated that: 1. an electron circles the nucleus only in fixed energy ranges called orbits; 2. an electron can neither gain or lose energy inside this orbit, but could move up or down to another orbit; 3. that the lowest energy orbit is closest to the nucleus. • Describe the wave/particle duality of electrons.
Energy is related to the Electron’s orbits
• When an atom is:
• The electron will:– Start at the – Jump to – Number of jumps is related to
• Key researchers: Bohr, Plank, Einstein
Schrodinger
Overview
Bohr’s Model of the Atom
• Electrons orbit the nucleus at:
• Electrons can be excited by:
• When excited, an electron will absorb only a certain amount of energy, (
Bohr’s model
• When excited, the electron
– Called the _________ state• The electron does not stay in the excited
state but falls back toward the nucleus and releases
Bohr’s model
Bohr’s model
• Ground vs. excited state
• Number of electrons that exist at specific energy levels
• Bohr’s model works for hydrogen but not for the complex atoms
Development of the Modern Atomic Model
Here are several models of the atom as they were developed in history:
............ ......
................
Electron Cloud Model
• Quantum Mechanical Model– Based on determining the probable location
of the electron
– Within the boundary of the
atom, its electrons can be
found 90% of the time
(based on probability)
Methods for Writing Electron Arrangements
• Orbital notation
• Electron configuration
• Noble gas notation
How are you going to remember the names for each method of writing the electron arrangement?
Rules for Electron Arrangement
• Aufbau:• Place the electron at the lowest energy orbital
possible. * • Pauli’s exclusion principle: Place a maximum of
2 electrons in each orbital.
• Hund’s rule: Place an electron in each orbital of a sublevel before pairing up.
* Check the diagram for the order of increasing energy level
Electron Arrangement Diagram
• n= principal energy level • Sublevels – s, p, d, f• Orbitals
– Each orbital holds 2 electrons with opposite spins, shown by arrows:
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
SPUD FarmMemory tool
Principal Energy Level Location of theValence electrons
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Examples: Sulfur & Iron
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Students:
Phosphorus
Calcium
Krypton
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Orbital Notation
• The orbital is indicated by a line____ wioth the name written below.
• Arrows represent the electrons.• Examples
Ne: ___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
Note: You must write both the lines and the orbital designations under the lines
1s
1s
1s 2s
1s 2s
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p 3s
Element Atomic # Orbital diagram Electron Configuration
H
He
Li
Be
B
C
N
O
F
Ne
Na
Practice• Element Atomic #
(Z)• H
• He
• Li
• Be
• B
• Orbital Notation___1s___ 1s ___ ___ 1s 2s___ ___1s 2s___ ___ ___ ___ ___1s 2s 2p 2p 2p
Practice
• C
• N
• O
• F
• Ne
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
Electron Configuration
• Principal energy level + sublevel • Use superscripts to show number of
electrons in each sublevel
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Electron Configuration: Sublevel diagram
• Determining order: Aufbau rules
n=1
n=2
n=3
n=4
n=5
• see figure 5-19 on p.138
Know how to make this chart!
1s
1s
1s 2s
1s 2s
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p 3s
Element Atomic # Orbital diagram Electron Configuration
H
He
Li
Be
B
C
N
O
F
Ne
Na
Check your electron configuration answers using the Periodic Table
Periods
S, P, D, F Blocks
18
Valence Electrons
• Electrons in the outermost (highest) principal energy level– Important– Participate in bonds to make compounds– 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
1s² 2s² 2p⁶ 3s² 3p⁴ 1s² 2s² 2p⁶ 3s¹1s² 2s²1s¹
Review: Electron Configuration
Write • Potassium
• Aluminum
• Chlorine
Circle the valence electrons.
Electron Dot Notation
• Represents valence electrons
K Al Cl
Maximum number = 8
Octet rule: atoms will lose, gain or share electrons to have 8 valence electrons & become stable
Introducing Noble Gas Notation
Analyze the following examples and propose the rules for writing Noble Gas Notation.
• chlorine [Ne] 3s²3p⁵• iron [Ar] 4s²3d⁶• zinc [Ar] 4s²3d¹⁰• barium [Xe] 6s²
Noble Gas Notation
• Short cut method for electron arrangement• Use the noble gas in the period above the
element
• Example:Na 1s² 2s² 2p⁶ 3s¹- Use Neon - Represent neon’s configuration 1s² 2s² 2p⁶as [Ne]- Use in Na: [Ne] 3s¹
Noble Gas Notation
Element
1s² 2s² 2p⁶ 3s² 3p⁶
1s² 2s² 2p⁶ 3s² 3p⁴ 1s² 2s² 2p⁶ 3s¹
1s² 2s² 2p⁶
Noble Gas Notation
Element1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
3d¹º4p⁶ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁵ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
3d¹º4p⁴ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º
4p¹1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
1s² 2s² 2p⁶ 3s² 3p⁶
Noble Gas Notation
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º 4p⁶ 5s²4d¹⁰ 5p⁵
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶ 5s² 4d¹⁰5p⁴
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶ 5s² 4d¹⁰5p²1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶ 5²1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶
Periodic Table: Order based on Electron
Configuration
Identify element– Write atomic number (Z)– Symbol
• Circle or highlight the valence electrons• Write the electron dot notation
1 18
2 13 14 15 16 17
3 4 5 6 7 8 9 10 11 12
Write the Electron Dot in the correct location for the element
Electron Configuration
• Aufbau is the Rule.Note: However, sometimes the electron
configurations are written in energy level sequence rather than Aufbau sequence.
• This is mostly used for the “d” sublevel.Aufbau sequenceTi: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²Energy level sequenceTi: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²
