Electrons resources Ted videos

Agenda: Warm-up: Identify 3 facts about electrons Where are the electrons? Electrons & Electromagnetic Radiation Bohr’s Theory Return Test: Mastery assessment See Assignment Page Mastery Test on

Electrons Arrangement in the Atom

Where are the electrons? Electrons are traveling at 6 x 10 ⁶m/sec around the nucleus Perspective of the speed: How long would it take a space vehicle to travel to the moon at the electron’s speed?

Fastest travel to the moon 8 hours, 35 minutes Pluto mission fly-by Distance from Earth to Moon: 383,401 km

Electrons: Earth to moon distance: 383,401 km –Convert to meters –Calculate the time to travel to the moon at the speed of an electron (6 x 10 ⁶ m/sec) : Distance = Time x Speed

Electrons & Electromagnetic Radiation By studying the light emitted when heating up a chemical sample, scientists better understood the electron: –Its position in the atom; –Its energy; & –Its role (bonding = forming compounds) Scientists used the electromagnetic radiation to study electrons

Electromagnetic Radiation Form of energy that has a wave-like properties Characterized by –Wavelength –Frequency –Energy

Electromagnetic spectrum See video clips: 1. NASA – saved –2. phys.energy.emspectrum/ Visible light Higher energy than visible light Lower energy than visible light

Electrons will give off electromagnetic radiation -When “energized” by heat, electricity, light or chemical reactions. How and why does this happen?

Energy exists in photons A photon has a specific amount (or packet) of energy Also use the word “quantum of energy” Photons with different energy will have specific wavelengths related to the energy

Bohr’s discovery and model: saved video from Discovery Education Starts with historical perspective

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

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

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

Emission Spectrum Lab Purpose: To relate the unique emission spectra lines of an element to the energy levels of the atom. Essential Question: What are the emission spectra for specific elements?

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How do neon lights produce the glowing colors? FACTS: Neon is a colorless, inert (non-reactive, non-flammable) gas Neon lights are tubes filled with neon gas.

Neon atoms Normal conditions –Electrons are at the ground state –No light (energy) is emitted Electricity passing through the tube –Atoms absorb energy –Electrons become excited and unstable –Electrons are pulled back toward the nucleus –Electromagnetic radiation is emitted

Elements and their electromagnetic radiation Emissions spectrum Unique for each element Electrons are excited by electricity When they are pulled back by the ____________, they give off __________

Emission Spectrum White light –Write the order of the colors Hydrogen: Nitrogen: Mercury: Neon: Other:

Emission Line Spectra

Emissions Spectra - Simulation harge-lampshttp://phet.colorado.edu/en/simulation/disc harge-lamps Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.

Emission Spectra Unique for each element Used to identify elements as part of unknown compounds

Hubble Space Telescope

Bohr Model Animations for Elements mistry/animations/CHE1.3-an-atoms.shtmlhttp://web.visionlearning.com/custom/che mistry/animations/CHE1.3-an-atoms.shtml mistry/animations/CHE1.3-an-atoms.shtmlhttp://web.visionlearning.com/custom/che mistry/animations/CHE1.3-an-atoms.shtml

Electrons in models of atoms How did scientists figure out the structure of atoms without looking at them? Try out different models by shooting light at the atom. Check how the prediction of the model matches the experimental results. Exploratory Lab en-atom

Quantum Model Video –

Video electron arrangement Video – (low volume)

Probable location of the electron The electron arrangement represents where an electron can be found 90% of the time.

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?

Where are the electrons?

Electron placement analogy Aspen Hotel

Hotel Analogy – cont

Rules for Electron Arrangement Aufbau: * Pauli’s exclusion principle: Hund’s rule: * 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:

Increasing Energy Nucleus Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spin

Increasing Energy Nucleus Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spin Examples: Sulfur & Iron

Increasing Energy Nucleus Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spin Students: Phosphorus Calcium Krypton

Increasing Energy Nucleus Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spin

Increasing Energy 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

ElementAtomic #Orbital diagramElectron 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 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ²

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!

ElementAtomic #Orbital diagramElectron 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 –1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 1s ² 2s ² 2p ⁶ 3s ² 3p ⁴ 1s ² 2s ² 2p ⁶ 3s ¹ 1s ² 2s ² 1s¹

Electron Configuration Write Potassium Aluminum Chlorine Circle the valence electrons.

Electron Dot Notation Represents valence electrons KAlCl 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] 3s ² 3p ⁵ iron [Ar] 4s ² 3d ⁶ zinc [Ar] 4s ² 3d ¹⁰ barium [Xe] 6s ²

Noble Gas Notation Short cut method for electron arrangement Use the noble gas in the period above the element Example: Na 1s ² 2s ² 2p ⁶ 3s ¹ -Use Neon -Represent neon’s configuration 1s ² 2s ² 2p ⁶ as [Ne] - Use in Na: [Ne] 3s ¹

Noble Gas Notation Element 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 1s ² 2s ² 2p ⁶ 3s ² 3p ⁴ 1s ² 2s ² 2p ⁶ 3s ¹ 1s ² 2s ² 2p ⁶

Noble Gas Notation Element 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d¹º4p⁶ 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d¹º4p⁵ 1s² 2s² 2p ⁶ 3s² 3p ⁶ 4s ² 3d¹º4p⁴ 1s² 2s² 2p ⁶ 3s² 3p ⁶ 4s ² 3d¹º 4p¹ 1s² 2s² 2p ⁶ 3s² 3p ⁶ 4s¹ 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶

Noble Gas Notation 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d¹º 4p⁶ 5s ²4d¹⁰ 5p⁵ 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d¹º4p⁶ 5s ² 4 d¹⁰ 5p⁴ 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d¹º4p⁶ 5s ² 4 d¹⁰ 5p² 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d¹º4p⁶ 5 ² 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 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

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 sequence Ti:1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 4s ² 3d² Energy level sequence Ti: 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 3d ² 4s ²