NOTES: 11/17/14 Let’s take a look at the Flame Test from Yesterday.

Let’s Review Atomic Structure Page 4

Niels Bohr’s Model of the Atom Placed the electrons in planetary Placed the electrons in planetary orbits around the nucleus. orbits around the nucleus. Each orbit is called an energy level and electrons will absorb or release energy as they move between orbits. Each orbit is called an energy level and electrons will absorb or release energy as they move between orbits. The energy absorbed or released is in the form of photons or particles of light energy. The energy absorbed or released is in the form of photons or particles of light energy. The lowest level was known as the ground state. The lowest level was known as the ground state.

Schrödinger Model of the Atom Mathematical model that predicts the location of the electrons of an atom: 1. Electrons are found in fuzzy clouds that predict the most likely place to find the electron. 2. Clouds are weird shapes 3. Each electron is unique and no two electrons will have the exact same “address”

Waves: Electrons and Light Energy Objective: To understand the electromagnetic spectrum and the relationship between energy, wavelength, and frequency

Electrons are found orbiting the nucleus and as you move down the periodic table, the electrons are farther away from the nucleus. Each of the rows on the periodic table are called periods or principle energy levels. The electrons in higher principle energy levels have more energy.

When elements are heated to high temperatures, some of their electrons are excited to higher energy levels. Characteristic colors of light are emitted when these excited electrons fall back to their original lower energy level, also known as periods.

The Wave: Labeling its parts A C D B Amplitude Wavelength Crest Trough

Parts of the Wave 5.Amplitude- the wave’s height from origin to crest (or from origin to trough) 6. Wavelength- the distance between two crests in a wave (or between two troughs) 7.Frequency- number of wave cycles to pass a given point per unit of time 8.hertz- the SI unit for frequency in cycles per second 9.Speed of light- product of frequency and wavelength equaling 3.0 X 10 8 m/s 10.Spectrum- range of wavelengths of electromagnetic radiation

Electromagnetic Spectrum

Frequency and Wavelength As the frequency increases ( more waves per second) the wavelength decreases (because waves are closer together).

2.White light separates into a rainbow of colors when it passes through a glass prism. What visible color has the longest wavelength & lowest frequency?

Planck’s Constant & Light Quanta Max Planck’s Constant: showed mathematically that the amount of radiant energy (E) absorbed/emitted is proportional to the frequency of radiation Energy of photons quantized by E = h x f In 1905 Einstein proposed light could be described as quanta of energy that behave as if particles. Light quanta are called photons.

Three Equations we use!!! Change f to λ

6. What is the energy of a photon of green light with a frequency of 5.80 x s -1 ? (h=6.626 x Js) E = (6.626 x Js) x (5.80 x s -1 ) E = 3.84 x J

7. Calculate the wavelength of yellow light emitted if the frequency is 5.10 x s -1 ? if the frequency is 5.10 x s -1 ? (c = 3.00 x 10 8 m/s) C = x f = C/ f = C/ f = ( 3.00 x 10 8 m/s) / 5.10 x Hz = ( 3.00 x 10 8 m/s) / 5.10 x Hz = 5.88 x m/s

8. Calculate the energy of a photon with a wavelength of 6.7 x m? E=hc λ E = (6.63 x ) (3.00 X 10 8 m/s ) 6.7 x m E = 3.0 x Joules

Homework: Calculations on page 6 Chemical & wavelength Ba 560 nm Ca 600 nm Cu 490 nm Sr 650 nm Li 700 nm Na 580 nm K 420 nm

Electrons and Light Waves Every element emits light when excited by the passage of an electric discharge through its gas or vapor. Atomic Emission Spectrum – light emitted by the element when passed through a prism.

Electrons in transition from higher to lower energy levels lose energy and emit light. Electrons in transition from higher to lower energy levels lose energy and emit light. It takes a quanta of energy (h x v) to raise the energy from ground state to excited state and vice versa.

Light is just a small part of the Electromagnetic Spectrum Radio waves Radio waves Microwaves Microwaves Infrared Infrared Visible light Visible light Ultraviolet Ultraviolet X-rays X-rays Gamma rays Gamma rays

Questions: Which color of visible light has the shortest wavelength? Which has a lower frequency, visible light or microwaves?

Wave Calculations Formulas: f  c = λ f f  E=h f Constants:  c = 3.0 × 10 8 m/s Speed of light  h= × Js Plank’s Constant Relates energy of a photon to frequency Variables: Variables:  f = frequency(Hz or s -1 )  λ = wavelength (m)  E= radiant energy (J)

Wave Calculations: Energy & Frequency Formula: f  E=h f Constant:  h=6.626 x Js Variables:  E= Radiant Energy Joules (J) f  f = Frequency Hertz (Hz or s -1 ) What is the energy of a photon of green light with a frequency of 5.76 x s -1 ? What is the energy of a photon of green light with a frequency of 5.76 x s -1 ? –Given: f = 5.76 × s -1 f = 5.76 × s -1 h= × J s h= × J s –Unknown: E=? –Equation: E=h f –Solution: E= ( × J s) E= ( × J s) × (5.76 × s -1 ) × (5.76 × s -1 ) E= 3.82 × J (3 s.f) E= 3.82 × J (3 s.f)

Wave Calculations: Frequency & Wavelength Formula: f  c = λ f Constant:  c = 3.0x10 8 m/s Variables:  λ = Wavelength (m) f  f = Frequency (Hz or s -1 ) Calculate the wavelength of the yellow light emitted by a sodium lamp if the frequency of the light is 5.12x10 14 Hz. Calculate the wavelength of the yellow light emitted by a sodium lamp if the frequency of the light is 5.12x10 14 Hz.

o Given: f f = 5.10x10 14 Hz c = 3.0x10 8 m/s –Unknown: ? –Unknown: λ = ? –Equation: f –Equation: c = λ f =c / f (rearranged) λ =c / f (rearranged) –Solution: = 3.0x10 8 m/s –Solution: λ = 3.0x10 8 m/s 5.12x10 14 Hz = 5.86 × m (3 s.f.) λ = 5.86 × m (3 s.f.)

1.What is the wavelength of light emitted if the frequency is 3.5 x s -1 ? 2.What is the frequency if the wavelength is 4.5 meters? 3. What is the energy of a photon of light with a frequency of 2.5 x s -1 ? 4. What is the frequency if the energy is 2.5 x J? 2.5 x J? Exit Ticket:

The Modern Atomic Theory: A Closer Look at the Electron

Where is the Electron? outside In the quantum mechanical model, the electrons are found outside the nucleus. To describe an electron’s location, we can includes 1.Its Energy Level 2.Its Sublevel 3.Its Atomic Orbital

Principle Energy Levels The first horizontal row of the periodic table represents the first or (n=1) principle energy level. Represented by the letter, n n = 1  First Energy Level Each new row on the periodic table starts a new energy level. Each energy level has a different number of sublevels, a different number of orbitals, and a different number of electrons.

The Bohr Model

Sublevels Based on the number of elements in our Periodic Table, there are four sublevels. s, p, d, f Each sublevel has a unique shape. The size of the sublevel depends on the energy level. Higher Energy Level = Bigger Sublevel

s-Sublevel sphere

p-Sublevel dumb bell This is only one of the p-sublevel atomic orbitals.

Since there are 3 orbitals in the p-Sublevel:

d-Sublevel Don’t need to memorize these!

f- Sublevel Don’t need to memorize these!

Summary of the Sublevels Sublevel Number of Atomic Orbitals Maximum Number of Electrons s12 p36 d510 f714

Atomic Orbitals All electrons are located in an atomic orbital or orbital. An atomic orbital represents the area in which there is a 90% chance of finding an electron. Each atomic orbital can hold two electrons. Inside these orbitals, electrons take random and unpredictable paths.

Processing Your Notes Question #1 1. Which sublevel has a dumbbell shape? a)s sublevel b)p sublevel c)d sublevel d)f sublevel The p-sublevel has a dumbbell shape, while the s-sublevel has a spherical shape.

Processing Your Notes Question #2 2. Which sublevels will have the same shape? a)3s and 3p b)3p and 4p c)1s and 2p d)4d and 3s The letter or sublevel determines the shape.

Processing Your Notes Question #3 3. Sodium is found on the third row or Period 3 of the periodic table. How many energy levels do the electrons of a sodium atom occupy? a)1 b)3 c)11 d)23 3 rd Row = 3 Energy Levels

Processing Your Notes Question #5 5. How many electrons can be held in one atomic orbital? a)2 b)6 c)10 d)14 Orbitals are like seats on the bus. Each seat/orbital will hold 2 electrons

Processing Your Notes Question #4 4.How many orbitals are found in a d-sublevel? a)4 b)5 c)10 d)14 Be Careful! The d-sublevel has 5 orbitals and holds 10 electrons. You will want to memorize that table!

Processing Your Notes Question #6 6. Which letter does not represent a current sublevel of an energy level? a)d b)f c)n d)p n represents the energy level not a sublevel.

Processing Your Notes Question #7 7. As scientists create new elements, we will need to add new sublevels to the four existing sublevels. In fact, the next sublevel will be called g. After looking at the trend in the number of orbitals for the current sublevels, how many orbitals would you predict would exist in a g-sublevel? a)7 b)8 c)9 d)32 s =1 p = 3 d = 5 f = 7 g = 9

Putting It All Together 1 s s & p s, p, & d s, p, d, & f 16 32

Electron Configurations Electron Configurations represent the location of the electrons in an atom or ion. 1s 2 2s 2 2p 5 the energy level of the electron (n) the sublevel the number of electrons

Processing Your Notes Question #8 8. How many orbitals are in the fourth energy level? a)4 b)8 c)16 d)32 For the fourth energy, you have s, p, d and f. s = 1 orbital p = 3 orbitals d = 5 orbitals f = 7 orbtials Add these up! = 16

Processing Your Notes Question #9 9. How many electrons are held in n=2? a)2 b)4 c)8 d)16 n=2 means the second energy level. s = 2 electrons p = 6 electrons Add these up! = 8 electrons

Processing Your Notes Question # Which of the following sublevels does not exist? a)1s b)2d c)3p d)4f On the first energy level, you only have 1s. On the second energy level, you only have 2s and 2p. On the third energy level, you only have 3s, 3p, and 3d. All four sublevels are on the fourth energy level.

Processing Your Notes Question #12 1s 2 2s 2 2p 6 3s 2 3p Which element is represented by this electron configuration? a)sodium b)sulfur c)argon d)selenium Add up the exponents! Since it is neutral, protons = electrons.

Processing Your Notes Question #13 1s 2 2s 2 2p 6 3s 2 3p What is the highest energy level in this electron configuration? a)2 b)3 c)4 d)6 Energy level represented by the coefficient or the big number.

Processing Your Notes Question #14 1s 2 2s 2 2p 6 3s 2 3p How many electrons are found in the s-sublevel? a)2 b)4 c)6 d) = 6

Processing Your Notes Question #15 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p Which sublevel has the most electrons? a)s b)p c)d d)f p = 13 electrons d = 10 electrons s = 8 electrons

Processing Your Notes Question #16 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p How many electrons are in the highest energy level? a)1 b)2 c)3 d)13 The “coefficient” determines the energy, so 4s and 4p are both on the highest energy level.

Processing Your Notes Question #17 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p What element is represented by the electron configuration? a)titanium b)copper c)gallium d)germanium Add up the exponents! Since it is neutral, protons = electrons.

Rule #1: Rule #1: Pauli’s Exclusion Principle Each atomic orbital can hold two electrons. Sublevel # of Orbitals Max # of Electrons s12 p36 d510 f714

Rule #2: Rule #2: Aufbau Principle Electrons will fill the atomic orbital with the lowest energy first. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Lowest Energy  Highest Energy

Blocks in The Periodic Table = s block = d block = p block = f block Row #

Sample Electron Configurations Hydrogen  1s 1 Beryllium  1s 2 2s 2 Fluorine  1s 2 2s 2 2p 5 Chlorine  1s 2 2s 2 2p 6 3s 2 3p 5 Potassium  1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Sample Electron Configurations Hydrogen __ Beryllium __ __ Fluorine __ __ __ __ __ Chlorine __ __ __ __ __ __ __ __ __ Potassium __ __ __ __ __ __ __ __ __ __