Electron Arrangement: CH 6

Electromagnetic radiation is all _____________________ that exhibits wavelike behavior and travels through space.

ü Examples are: ____________________________________________

Properties to describe a wave are:

1) wavelength (l) : distance between 2 equal points on a wave; measured from crest to crest usually in nanometers(1nm = 1 x 10^-9m)

2) frequency(u ) : number of waves that pass a certain point per second; measured in hertz(Hz); 1 Hz = 1 wave per second; can be expressed 1/s

Speed of light

ü equals 3.0 x 10⁸ m/s

ü represented by the symbol “c”

ü all _________________ travel at this speed

ü Notice that frequency & wavelength are ________________ proportional, as frequency ________________________, wavelength decreases.

ü LOOK at the electromagnetic spectrum and identify the same relationship

Sunlight (white light) is a continuous spectrum of _______________________

Electromagnetic Spectrum (EM spectrum)

ü Identifies all forms of electromagnetic radiation

ü Notice that as frequency increases, the amount of energy _____________________. This is a _____________________ proportional relationship.

ü ________________________ is a small region within the spectrum that has wavelengths/frequencies that are eyes can detect.

ü ROY G BIV is a mnemonic to help you remember the colors of the spectrum. Red is near _________________ and violet is near ultra violet.

Review of Models

Greek/Dalton view Plum Pudding model Rutherford Model

Bohr Model

Why don’t electrons fall into the nucleus?

ü Electrons thought to move like ____________________ around the sun in circular orbit at different levels (energy levels)

ü There are amounts of __________________ that separate 1 level from another.

ü Think of the energy levels as rungs of a _________________.

ü There is no in-between energy!

ü The farther away an energy level is from the nucleus,

the more _____________ it attains!

ü Ground state: lowest energy level state

ü Excited state: a higher state

ü Electrons can move from a ground state to an excited state by ______________________ energy whereas they __________________ energy when moving from the excited state to a ground state.

Quantum Mechanical Model (Modern view of the atom)

ü Electrons have both particle & _____________ like behavior.

ü They exist in _________________________.

ü Electrons do not have ___________________. They only can have a probability of being located in a certain place but its position cannot be described exactly. Their energy & positions are described by ________________________.

ü Electrons can be found in a blurry ______________________.

ü Quanta: amount of energy an electron can ________________ as it moves higher or release when it moves ___________________.

The position of an electron can be described by 4 quantum numbers

1. Principal Quantum Number: the _________________ of an atom

v Represented by the symbol ___________. There are 7.

v Within each energy level there are several shapes called _________________.

v To calculate n, look a the periodic table and determine the __________________ number of the element

Example: Beryllium Strontium

2. Orbital Quantum Number: the shape of the orbital

v Represented by the symbol l. :There are several cloud shapes

v An orbital is defined as the _________________ where there is a high probability of finding an _________________.

v Each orbital holds ___________ electrons.

“s” orbital

v _______________ shaped

v there is only ______ orientation

v represented in the periodic table as

groups 1A and 2A + helium

v first seen in the 1^st energy level

v maximum ______ electrons

“p” orbitals

v ____________________ shaped

v there are ______ orientations(positions)

v represented in the periodic table

as groups 3A- 8A

v first seen in the 2^nd energy level

v maximum ____ electrons

“d” orbitals

v ___________________ shaped

v there are _______ orientations(positions)

v represented in the periodic table as

the transition metals, group 3B – 2B

v first seen in the 3^rd energy level

v maximum ____ electrons

“f” orbitals

v ___________________ shaped

v there are _______ orientations(positions)

v represented in the periodic table as

the inner transition metals, lower block

v first seen in the 4^th energy level

v maximum ____ electrons

v To calculate l: find the numbers within the range of [0 to (n-1)]

l = 0 correlates to “s” orbital l = 1 correlates to “p” orbital

l = 2 correlates to “d” orbital l = 3 correlates to “f” orbital

Example: n =1 n = 3

3. Magnetic Quantum Number: the position or orientation of the orbital about the x, y and z axes

v Represented by the symbol m_l.

v To calculate m_l : find the numbers in the range and count how many there are. This represents the # of positions

Example: l = 3 l = 2

4. Spin Quantum Number: the direction that the electrons spins

v Can only have 2 values

v It will spin either clockwise, represented by a ____________ or counter clockwise where it is represented by a ______________

Summary

(n) (l) l = [0 to (n-1)] n² 2n²

Energy Level

# of sublevels

Type of sublevel

Total # of orbitals

Total # of electrons

v Energy levels are also called ___________________.

v As seen in the chart above, 1^st energy level has a maximum of _____ electrons, 2^nd energy level has a maximum of _______ electrons, 3^rd energy level has a maximum of ____ electrons, and 4^th energy level has _____ electrons

v When drawing simple Bohr models, when you get the 3^rd energy level, place 8 in the 3^rd energy level first, then 2 in the 4^th energy level, the remainder of the 18 are placed into the 3^rd. Then place in the 4^th if needed.

v Valence electrons are the electrons found in the ____________ shell (energy level) They are not very _____________.

Examples

H O Cl

Short cut to determine valence electrons

v The group # next to the letter A represents the valence electrons.

Electron Dot notation

v Valence electrons are represented by dots around the element symbol

Li Be C N Ne

Electron Configuration

4p¹

v Is an _________________ of an electron

v Electrons must be placed in the ____________

possible energy levels first (ground state)

3 rules that govern electron configuration

1. Aufbau Principle: electrons must be placed in _______________ of lowest energy levels first

v Can use the periodic table as a guide or use diagram below; If you use the periodic table, need to make 2 modifications:

Transition metals: period # -1 is the energy level

Inner transition metals: period # - 2 is the energy level

v Sequence of energy level is _______________

v Sequence of sublevels is ______________

v An orbital can ____________ within different energy levels

v __________is lower in energy than 3d

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f

6s 6p 6d

7s 7p

2. Pauli Exclusion Principle: electrons in the same orbital must have opposite ___________.

3. Hund’s rule: When electrons occupy orbitals of the __________ energy , 1 electron enters each orbital first until they are all ______________ filled. Then and only then can a second electron be added to those orbitals.

__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __

You Try !

Electron Configuration

H He

Li B

N Ne

Mg Ca

Fe As

Orbital Notation

v Shows the spin of the electron

v Uses _______________ ( ¯ )to display electrons moving in __________________ directions to prevent repulsion

v ________ or represents an orbital

Example: Orbital 1s 2s 2p_x 2p_y 2p_z

H

He

Li

N

O

Noble Gas Configuration

v also known as _____________________ configuration

v Place the ___________________ that comes before the element in brackets and then start your configuration from that point

v The brackets represent the _________________ electrons

Example: Full electron configuration vs. shorthand configuration

Al

Ge

Hf

Exceptional Configurations

v Elements up to vanadium (V) follow Aufbau principle

v After that, there are lots of exceptions to the rule

****Reasons for exceptional configuration

1. Completely filled orbitals are more ______________ than half filled or partially filled orbitals.

2. ___________________ orbitals are more stable than partially filled orbitals.

Exceptions you need to know are Cu Cr Mo Ag

Cr

Ag

Electron Configurations for Ions

v Ions have a _____________________ configuration

v Cations: removal of 1 or more _________________ electrons from highest energy level and sublevel; for transition metals, always remove electrons from _______ sublevel before the d sublevel

Sodium atom: Na

Sodium ion: Na⁺¹

Titanium: Ti

Titanium(II) ion: Ti⁺²

v Anions: _____________ of 1 or more valence electrons from the highest energy level and sublevel

Chloride ion : Cl^-1