Honors Chemistry

*Unit 1 Notes: The Atom

*Atomic Timeline

http://www.google.com/url?sa=i&source=images&cd=&cad=rja&docid=nnSswWer_bWpqM&tbnid=6_F6asBgf4IveM:&ved=0CAcQjB0wAA&url=http%3A%2F%2Fwww.docstoc.com%2Fdocs%2F2197377%2FHistory-of-the-Atom-Timeline&ei=Lj0eUrToIdbBsATc-YCoBQ&psig=AFQjCNGiHQcb3bnDY0VcwwwaBXbg6JrjvQ&ust=1377799854621767

*Element organization on

the Periodic Table:

*Element symbols: Always a capital letter or capital letter followed by lowercase

*Vertical columns are called groups or families.

*Horizontal rows are called periods.

*Metals are on the left of the staircase line; nonmetals are on the right side.

*******EXCEPT: Hydrogen

*Metals: good conductors of heat & electricity; malleable; ductile; lustrous; most are strong; lose e- when bonding

*Nonmetals: poor conductors; many are gases; some are brittle solids; gain e- when bonding

*Metalloids: on the staircase (B, Si, Ge, As, Sb, Te, Po, At); semiconductors

*The Atom

*Atomic Symbols:*p+: proton

*n°: neutron

*e-:electron

*A: mass #

*Z: atomic #

The Atom: Location Charge Relative Size

Proton Nucleus + 1Neutron Nucleus 0 1Electron Electron

Cloud- 1/1840

*The Atom

*Atoms are the smallest piece of matter that can be used to identify a substance.

*Each element has a unique number of protons in each atom.*Identifying atoms using your periodic table:

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*The Atom

*Atoms of the same element do NOT always have the same number of neutrons in the nucleus.

*The mass number is the total number of protons and neutrons in the nucleus.

*When atoms are identical EXCEPT for the number of neutrons, they are called isotopes of the same element.

*The atomic mass printed on the periodic table is the average mass of the different isotopes. Its units are atomic mass units (amu).

*Ways to write isotopes:

* http://www.google.com/imgres?sa=X&biw=1366&bih=643&tbm=isch&tbnid=sO9osPgr_kvfPM:&imgrefurl=http://chemwiki.ucdavis.edu/Physical_Chemistry/Atomic_Theory/Atomic_Mass&docid=g6zq01l9iti72M&imgurl=http://chemwiki.ucdavis.edu/%2540api/deki/files/4829/%253DIsotope_Notation.png&w=500&h=300&ei=u00fUq7ALoWusQSD74DwAQ&zoom=1&ved=1t:3588,r:7,s:0,i:102&iact=rc&page=1&tbnh=174&tbnw=281&start=0&ndsp=15&tx=164&ty=68

https://www.google.com/imgres?imgurl&imgrefurl=http%3A%2F%2Fwww.m2c3.com%2Fchemistry%2FVLI%2FM1_Topic2%2FM1_Topic2_print.html&h=0&w=0&sz=1&tbnid=rtIsimbpgv5nTM&tbnh=76&tbnw=279&zoom=1&docid=jZ-a1trpejG2kM&ei=PE4fUoKcOYbO9QS5xYGQAw&ved=0CAIQsCU

Nuclear Symbol

Hyphen notationOxygen-17O-17

*Calculating average atomic mass:(Mass x % abundance) + (mass x % abundance) + (mass x % abundance) + etc.*1. Neon-20 has a mass of 19.992 amu and Neon-22 has a

mass of 21.991 amu. In an average sample of Neon atoms, 90% will be Neon-20 and only 10% will be Neon-22. Calculate the average atomic mass of Neon.

*2. 76% of Chlorine atoms are Cl-35 which has a mass of 34.969 amu. 24% of Chlorine are Cl-37 which has a mass of 36.966 amu. What is the average atomic mass of chlorine?

*Nuclear Radiation:

*Henri Becquerel wrapped uranium salt with photographic film and placed in the sun…white spot left on film; However, it worked again without being exposed to sun light. The uranium must be releasing energy.*Marie Curie continued Becquerel’s work. She discovered other elements that also release this energy…called it “radioactivity”. *Also discovered radium and polonium.

*Nuclear Radiation:

*Properties of Radioactive Elements:

*1. Alters photographic film

*2. Makes some compounds fluoresce (glow)

*3. Produces electric charge

*4. Damages living cells

*Radioactive Decay:

*3 Main Types of Decay:

*1. Alpha (α): releases a 4/2 He nucleus; look like helium, can burn skin but can be blocked by a sheet of paper

*2. Beta (β): releases an electron; neutron inside the nucleus breaks apart and releases an electron (leaving a proton behind); 100x stronger than alpha blocked by metal

*3. Gamma (γ): releases energy waves; very high energy electromagnetic waves; most dangerous; can be blocked by thick concrete or thick lead

*Radioactive Decay

http://www.google.com/imgres?sa=G&biw=1366&bih=643&tbm=isch&tbnid=FNPpLfPrpWmqfM:&imgrefurl=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Waste-Management-Overview/&docid=McDjZUXr0lJEHM&imgurl=http://www.world-nuclear.org/uploadedImages/org/info/Nuclear_Fuel_Cycle/Nuclear_Wastes/wast3.gif&w=379&h=168&ei=i5UgUoD0HYnKsATcvoH4Dw&zoom=1&ved=1t:3588,r:32,s:0,i:185&iact=rc&page=2&tbnh=114&tbnw=258&start=15&ndsp=21&tx=101&ty=50

*Nuclear Reaction Problems:

*8.

*9.

*10.

*11.

*Radioactive Decay

*Transmutation: when one element turns into another

*Two ways it can occur:* 1. Radioactive decay (natural)* 2. particles bombard a nucleus (laboratory)

*Allows chemists to produce elements that don’t naturally occur (all elements > #92 are synthetic, and some isotopes of other elements)

*Mass Defect:*The difference between adding up the particle masses and the total

mass of the actual atom*If you add the masses of helium’s particles, one atom should weigh

4.033 amu, but it only weighs 4.022 amu. What happened to the missing mass?*This was explained by Albert Einstein

*Half Life:

*The time required for half of the atoms to decay in a radioactive sample.

*Can be used to date the remains of plants and animals.

*After each half life, half of the atoms have decayed into smaller elements.

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*Half-Life Problems

*12.If Polonium-32 has a half life of 14.3 days and you start with 4.0 mg, how many mg will you have after 57.2 days?

*13.The half life of radon-222 is 3 days. If you wait 15 days and find 50 grams of radon-222, how much was in the starting sample?

*Nuclear Fission

*Splitting of a nucleus into smaller fragments*When nucleus splits it releases energy (nuclear power)*High nuclear waste*Atomic bomb (U, Pu)*When nucleus splits, it releases neutrons that crash into other atoms causing them to split… “chain reaction”

http://www.google.com/url?sa=i&source=images&cd=&cad=rja&docid=LzugVAmPNfCyEM&tbnid=H04mChcEyAvnSM:&ved=0CAcQjB0wAA&url=http%3A%2F%2Flibrary.thinkquest.org%2F3471%2Fabomb.html&ei=Q0EeUvydAuK0sAT4loGoBw&psig=AFQjCNHVttvous4jVsp_aSvuyO5vuDee2w&ust=1377800899097039

*Nuclear Fusion

* https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=l8vXaJS4H6PKuM&tbnid=EtdykNacTW_6tM:&ved=0CAQQjB0&url=http%3A%2F%2Fwww.atomicarchive.com%2FFusion%2FFusion1.shtml&ei=_UEeUqusL5O88wSi9oHQDg&psig=AFQjCNGTP20KLqwni4--LmgDQrntLKA7iw&ust=1377801024997787

*Combining nuclei to produce larger atoms*Produces more energy than fission*Requires very hot temps*Occurs on the sun and stars*Low waste*H bomb (H fusing He)

*Light and Electrons

*Different elements release waves of energy with different wavelengths when their electrons are excited*Electromagnetic waves (also called radiation) can travel through empty space and travel through some matter*All of these waves travel with a velocity of 3x108 m/s through empty space*Wavelength v. Frequency: inversely proportional (when one goes up, the other goes down)*Frequency v. Energy: directly proportional (when goes up, the other goes up)

*Light and Electrons

* https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=dNeokQHrafq1VM&tbnid=yYWwmoFv0tUrpM:&ved=0CAQQjB0&url=http%3A%2F%2Fwww.lbl.gov%2FMicroWorlds%2FALSTool%2FEMSpec%2FEMSpec2.html&ei=UgYtUsGfOZO-9gSJ8IGwDg&bvm=bv.51773540,d.eWU&psig=AFQjCNHgMK4-dRqZh5-tyf7JVuwau3WrxQ&ust=1378768379142251

*Electromagnetic spectrum

*1. What type of wave has a wavelength of 5 X 103m?

*2. If a light wave has a wavelength of 5.3 x 10-7m, what color is it?

*3. An electromagnetic wave travelling through space has a frequency of 7.5 X 1020 hz. What is its wavelength? What kind of wave is it?

*4. Which waves carry more energy, red light waves or violet light waves? Explain!

*Photons

*Some evidence suggests that light travels in clumps of particles called photons instead of continuous waves. *The German scientist Max Planck studied photons and said that atoms of different elements have different amounts of energy that can be lost or gained. *He called this minimum amount of energy the Quantum energy.

*Wave Particle Duality

*Einstein believed that light has properties of BOTH waves and particles*He called this Wave Particle Duality *This means that photons of light travel in “packets” called quanta and move up and down like a wave as they travel from one location to another*Electrons act as waves as well as particles*Energy acts as particles as well as waves

*Photoelectric Effect

* https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=RjckGpXhNy_B4M&tbnid=8zEMWSte6Ag9PM:&ved=0CAQQjB0&url=http%3A%2F%2Fastrophysics.pro%2Fexperiments%2Fphotoelectric-effect%2F&ei=1gstUpbAHIaA9gTRgoCoBA&bvm=bv.51773540,d.eWU&psig=AFQjCNG7HanVbQg8lkRhoYih1zJ92UKIzg&ust=1378770196315156

*Electrons are released from matter when it is hit by electromagnetic waves

*Atomic Spectra

*As atoms absorb energy, electrons move into higher energy levels*When the electrons return to lower energy levels, the release energy in the form of visible light*No two elements release the exact same spectrum of light waves*Elements can be identified by the colors of light they release when electrons jump back to the lower energy levels

*Atomic Spectra

*Neils Bohr explained that electrons circle the nucleus in specific orbits. *The lowest possible energy level of an electron is called its ground state(This is the normal location of the electron.) *If an electron absorbs energy, it moves up an energy level absorption*If an electron gives off energy, it moves down an energy level (emission).