What are Waves?

Parts of waves:

Types of Waves:

What do you think of?

Waves

Types of Waves:

Light waves - vibration of photons

Sound waves - Vibration of air molecules and atoms

Water waves - vibration of water molecules

Parts of waves:

AmplitudeTroughWavelengthFrequencyCrest

Parts of Waves?

TroughCrest

AmplitudeWavelength

What waves do:

Reflection:

Refraction

Diffraction:

What waves do:

Interference

Constructive Destructive

Particles (Matter)

What is Matter?

What do you think of?

What force defines how matter can behave?

Is Light A Wave or Particle

·This has been a debate for the same amount of time as the debate about what matter is made up of

Ancient Greeks

·Aristotle: originally thought that light had to be a disturbance of the element AIR

·Democritus: originally thought that light had to be composed of small subatomic particles: Solar Atoms

·Christian Huygens (1690):

·Predicted that light was a wave using the idea that light propagated as a disturbance in the air·Sir Isaac Newton (1690) ·Light was made up of particles corpuscle

·Robert Hooke: Newton’s Rival

·Stated that Newton was wrong—light was a wave·Newton did not publish his theory until after Hook passed away

·Thomas Young (1773):

·First to actually use evidence that light was actually a wave·Double slit experiment·Same experiment was later used to prove that light was actually a particle

·Do you think light is a wave or a particle? WHY?!?!?

Lasers can pop balloons

Shadows

Lasers can be used in surgery to cut parts of the body

Rainbows (prisms)

Duality of Light Video

ElectronsChapter 5.1

Light as a wave

Originally scientist believed that light was a wave and that it only acted as such

However, as science progressed this concept changed

Electromagnetic radiation:

A form of energy that exhibits wavelike behavior as it travels through space

Visible Light

Microwaves

X-rays

Gamma rays

Radio waves

Parts of Waves:

Trough

Crest

Amplitude

Wavelength

Wavelength (λ): Is the shortest distance between equivalent points on a continuous wave (crest to crest or trough to trough) commonly measured in meters, centimeters or nanometers

Crest: Top of the wave

Trough: Bottom of the wave

Amplitude: Is the wave's height from the origin to a crest, or from the origin to a trough. (wavelength and frequency do not affect amplitude)

Frequency (υ): Is the number of waves that pass a given point per second. Hertz (Hz) is the SI unit for frequency

Wave Mathematical RelationshipsC = λ * υ

λ - Wavelength

υ - frequency

C - Speed of light

Speed of light is 3.00 x 108 m/s

This speed is constant for all electromagnetic waves inside a vacuum (space)

Practice: What is the frequency of an X-ray with a wavelength of 1.15 x 10 -10 m?

Note: As frequency increases, wavelength decreases (inverse relationship)

Note: As frequency increases, energy of the wave increases

Electromagnetic Spectrum:

A spectrum that includes all forms of electromagnetic radiation, with the only difference in the types of radiation being their frequencies and wavelengths

ROYGBIV

Light as a particle:

Light as a wave failed to explain:

why heated objects emit only certain frequencies of light

Why some metals emit electrons when light at a given temperature shines on them (photoelectric effect)

These colors correspond to different wavelength and frequencies

Max Plank (1900)

A German physicist was searching for an explanation of this phenomenon

He found that matter could either gain or lose energy but only in small specific amounts called quanta

Quantum-- is the minimum amount of energy that can be gained or lost by an atom

(think of stepping stones)

Energy of a Quantum

E = h * υ

Plank came up with a relationship between the energy of a quantum and the frequency of a wave

E -- Energy

h -- Plank's Constant

h = 6.626 x 10-34 J*sυ -- frequency

This showed scientists that these quantum (abortions and emission of energy) were whole number multiples of hυ

hυ 2hυ 3hυ 4hυ 5hυ 8hυ7hυ6hυ

Photoelectric Effect

Some metals will eject electrons form their surface with light of a certain frequency (or higher) hits their surface

Albert Einstein (1905)

Duality of light--light can be both a wave and a particle

It is a beam of bundles of energy called photons

Photons--a massless particle that carries a quantum of energy. This energy depends on the frequency of the photons

EPhoton = hυ

Ephoton = Energy of the photon

h = Plank's Constantυ= frequency

The blue color in some fireworks occurs when copper chloride is heated to approximately 1500K and emits blue light of wavelength 4.50x102 nm. how much energy does one photon of this light carry?

Atomic Emission Spectra

Electrons around an atom's nucleus will absorb energy in quantums, the electrons will then jump up and fall back down to what is called ground state and release that same amount of energy.

This energy has a specific frequency which can be seen as colors; meaning the frequency of the photons release is within the visible light of the electromagnetic spectrum

Each element has a very specific range of colors that are emitted

Atomic Emission Spectra: the set of frequencies of the electromagnetic waves emitted by atoms of the element

These are used to identify elements and elements within compounds

Quantum Theory and the Atom

Chap. 5.2

Niels Bohr (1913)

Studied the hydrogen atom and, based off of Planck's and Einstein's concepts of quantized energy, determined that the atom only had certain allowable energy states

·Lowest possible energy state is called Ground State

·When the atom absorbs energy, it is said to be in an Excited State

Bohr's Model of the Atom

Borh suggested that the electrons around the hydrogen atom could only be allowed in certain circular orbits around the nucleus

·The smaller the electron's orbit, the lower the atom's energy state or energy level

·The larger the electron's orbit, the higher the atom's energy level

Bohrs Atomic orbit

Quantum number

Orbit Radius (nm)

Corresponding atomic energy level

Relative Energy

First n = 1 0.0529 1 E1

Second n = 2 0.212 2 E2 = 4E1

Third n = 3 0.476 3 E3 = 9E1

Fourth n = 4 0.846 4 E4 = 16E1

Fifth n = 5 1.32 5 E5 = 25E1

Sixth n = 6 1.90 6 E6 = 36E1

Seventh n = 7 2.59 7 E7 = 49E1

Quantum Number: The number Borh gave to each orbital around the atom

Energy State

Ground State for Hydrogen is when hydrogen's single electron is in the first energy level or the first quantum level

·The hydrogen atom does not give off energy in the ground state

Once energy is added the single electron moves up to a higher energy orbit (such as n = 2) making the atom in an excited state

·The electron will fall back into its original quantum level (ground state) and release the energy gained as a photon

Since these quantums are set only a set energies can be absorbed and emitted by the atom, therefore only specific frequencies are emitted by the atom

Louis de Broglie (1924)

Thought that if Light can be have both wave and particlelike characteristics, then can matter (electrons) behave as both

Predicted that all moving particles have wave-like characteristics (including cars or baseballs)

λ = h/mυ

λ = Wavelength

h = planck's constant

m = mass

υ = frequency

Werner Heisenberg (1901-1976)

·Stated that it is impossible to take any measurement of an object without disturbing the object

Heisenberg uncertainty principle: states that it is fundamentally impossible to know precisely both the velocity and position of a particle at the same time

·Meaning Bohr's defined orbits were not accurate

Erwin Schrodinger (1926)

Austrian Physicist

Quantum Mechanical model of the atom: the atomic model in which electrons are treated as waves

·This allowed for scientist to determine particular volumes of space around the nucleus in which the probability of finding an electron is very high

Atomic Orbital: the probable location of an electron within an atom

Hydrogen's Atomic Orbitals

Principal quantum number (n)--number of the atomic orbitals. (also called Principal energy level)

·As n increases, the orbitals become larger and have more energy

These levels contain what are called energy sublevels

·The first energy level contains 1 sublevel; the second energy level contains 2 sublevels,the third energy level contains 3 sublevels, ect.

There are a total of 4 sublevels labeled s, p, d and f

·These sublevels are then broken down further into orbitals

·A single orbital can only hold 2 electrons total

·Meaning if there are 3 orbitals there can be a total of 6 electrons in that sublevel

Periodic breakdown of levels and sublevels

S-Sublevel

The s-sublevel has a spherical shape

The s-sublevel only has one orbital and therefore s-sublevel can only hold two electrons

P-Sublevel

The p-sublevel is a dumb-bell shape

The p-sublevel contains 3 orbitals and therefore contains 6 electrons total

d-sublevel

The d-sublevel has two shapes one that like two dumb-bells put together and the other is like a single dumb-bell

The d-sublevel contains 5 orbitals and therefore can hold up to 10 electrons

f-sublevel

The f-sublevel has a very complex shape

The f-sublevel contains 7 orbitals and therefore contains 14 electrons

Periodic breakdown of levels and sublevels

Notice that the energy level 1 contains only 1 sublevel (s), energy level 2 contains 2 sublevels (s and p), energy level 3 contains 3 sublevels (s, p, and d), and energy level 4 contains 4 sublevels (s, p, d, and f)

·Which is the order of the orbitals: s, p, d, and f

Electron Configuration

Chap. 5.3

1s 2s2p 3s3p4s3d4p 5s4d5p6s4f 5d6p7s5f6d7p

Review

Energy levels can be found by looking at what on the periodic table?

Basic goal: Break the energy levels down into sub-levels and orbitals!

Energy levels

Sub-levels

Orbitals

(s, p, d, and f)

Only 2 electrons

Electron Configuration

This is the arrangement of electrons in an atom

Review

How many electrons can the s-sublevel hold?How many electrons can the p-sublevel hold?How many electrons can the d-sublevel hold?How many electrons can the f-sublevel hold?

Where can each of the sublevels be found on the periodic table?

Rules for Electron Configuration

There are three rules that must be followed while writing electron configurations

Rule 1: Aufbau Principle

Rule 2: Pauli Exclusion Principle

Rule 3: Hund's rule

·Each electron occupies the lowest energy orbital available

·A maximum of two electrons can occupy a single orbital, but only if the electrons have opposite spins

·Single electrons with the same spin must occupy each equal energy orbital before additional electrons with opposite spins can occupy the same orbital

Rule 1: Aufbau Principle

·Each electron occupies the lowest energy orbital available

This means that you must first be able to determine the order of energy levels, sub-levels and the orbitals within those sub-levels

Energy levels move in the order of periods down the periodic table

·Order: 1, 2, 3, 4, 5, 6 and 7

Sub-levels are in the order of s, p, d, and f and how they appear on the periodic table

2p1s

2s 2p

3s 3p

4s 4p3d

4d5s 5p

6s 6p5d

7s 6d

4f

5f

7p

·Notice that the d-level and f-level are "behind" the s and p-level

Rule 2: Pauli Exclusion Principle

·A maximum of two electrons can occupy a single orbital, but only if the electrons have opposite spins

Remember that the sub-levels contain orbitals. S-sublevel contains 1 orbital, p-sublevel contains 3 orbitals, d-sublevel contains 5 orbitals, and f-sublevel contains 7 orbitals

·s-sublevel can only hold 2 electrons

·p-sublevel can only hold 6 electrons

·d-sublevel can only hold 10 electrons

·f-sublevel can only hold 14 electrons

This means that an energy level that contains ALL sublevels can only contain 32 electrons all together

S

p

d

f

1

2

1 2 3 4 5 6 7 8 9 10

51 2 3 4

6

1 2 3 4 5 6 7 8 9 10 11 1412 13

Lets say we want to write the electron config for Nitrogen

S

p

d

f

12

1 2 3 4 5 6 7 8 9 10

51 2 3 4

6

1 2 3 4 5 6 7 8 9 10 11 141213

Practice:

Write the electron diagram for the following elements:

Calcium

Phosphorus

Oxygen

Argon

Cobalt

Silver

Rule 3: Hund's rule

·Single electrons with the same spin must occupy each equal energy orbital before additional electrons with opposite spins can occupy the same orbital

Lets look at our electrons configuration for Nitrogen

1s22s22p3

1s 2s 2p

This is called an orbital diagram

Practice:

Write the orbital diagram for the following elements:

Manganese

Potassium

Gallium

Neon

Noble gas notation:

Where are the noble gasses on the periodic table?

Noble gas notation makes writing electron configs and orbital diagrams easier (and shorter)

·Let say we wanted to write out the electron configuration for Bromine

·Now instead of write ALL of that, determine the noble gas that comes BEFORE Bromine and write everything in the configuration that comes AFTER that point

Practice:

Write the Nobel gas notation for the following elements:

Sodium

Sulfur

Arsenic

Iron

Silicon