q2 cumulative

PROPERTIES OF ATOMS AND ELEMENTS

1. Define the atom

   1. Atoms are the building blocks of all matter. Made up of protons and neutrons in the nucleus and electrons orbiting in shells

2. History of modern atomic theory

   1. Discontinuous Theory - Democritus ~ 400 BCE

      1. atoms are the smallest unit of matter & are indivisible

   2. Modern Atomic Theory - John Dalton ~ 1803

      1. Each element consists of the same type of atom which is unique to that element

   3. Discovery of Electrons & Plum Pudding Model - JJ Thomson ~ 1897 & 1904

      1. Discovered electrons while experimenting with cathode ray tubes

      2. Plum pudding model showed atom as a positive sphere filled with electrons 

   4. Quanta/Photons - Albert Einstein ~ 1905

      1. Light not only acts as a wave but also particles

   5. Nuclear Atom Model - Ernest Rutherford ~ 1911

      1. Discovered nucleus from gold foil experiments

      2. Tiny densely positively charged core called nucleus with electrons orbiting around it

   6. Bohr Model - Niels Bohr ~ 1913

      1. Bohr’s Postulates: 

         1. Only orbits of certain radii, corresponding to certain energies, are permitted for the electron in the hydrogen atom

         2. An atom with an electron in a permitted orbit has a specific energy and is in an allowed energy state. An atom in an allowed energy state will not radiate energy, and therefore the electron will not spiral into the nucleus

         3. Energy is emitted or absorbed by the atom only as the atom changes from one allowed energy state to another. This energy is emitted or absorbed as a photon. 

   7. Discovery of Protons - Ernest Rutherfod ~ 1919

      1. Sent alpha particles in nuclei which causes them to emit particles called protons

   8. Electron Cloud Model - Erwin Schrodinger ~ 1926?

      1. Built on work of other physicists to make equations to locate electrons

      2. Led to discovery of electron cloud

   9. Heisenberg Uncertainty Principle~ 1927

      1. States that we cannot know exact location and speed of a particle with much accuracy

      2. Formula: m(delta v) * delta (x) >= h/4pi

   10. discovery of neutrons - James Chadwick ~ 1932

       1. Beryllium bombardment experiment that was similar to gold foil : discovered neutrons

   11. Nuclear fission - lise meitner ~ 1938

       1. Split atom & first to coin the term

   12. Nuclear shell model - maria goppert-mayer ~ 1949

       1. Protons and neutrons are split into shells based on energy level

   13. Discovery of quarks - murray gell -mann ~1964

       1. Indivisible particle that makes up protons and neutrons 

   14. De Broglie equation:

       1. lambda=h/p

3. Light and quantized energy

   1. What causes bright-line spectra

      1. the release of photons which is caused by the electron energies going down

4. Rydberg Equation

   1. 1/λ=R(1/n²₁-1/n²₂)

      1. R= 1.097 * 10^-7 m^-1

      2. λ= wavelength

      3. n1= ending energy level

      4. n2= starting energy level

   2. Four visible light in hydrogen atom

      1. Two violet

      2. One red

      3. One teal 

5. Quantum theory

   1. Orbital shapes and orientations

      1.  The shape of an orbital connects all the points that have the same probability density 

      2. The size encompasses 90% if the probability  

   2. Quantum numbers (n, l, m_l, m_s)

      1. n = principle quantum number (size, energy) (pv: 1, 2, 3..)

      2. L = orbital quantum number (shape) (pv: 0, 1, 2…, n-1)

      3. m_l= magnetic quantum number (orientation) (pv: -l, …, -1, 0, 1, …, l)

      4. m_s= spin quantum number (vector can point in different connections) (pv: -½, ½)

   3. Aufbau principle

      1. Fill the lowest energy subshells first

   4. Hund’s rule

      1. Every orbital in a subshell is filled with on electron before a subshell is doubly filled

      2. All single filled electrons have the same spin

   5. Pauli exclusion principle

      1. every orbital can have two electrons max with different spins

6. Electron configuration and orbital diagrams

   1. Octet rule

      1. States that atoms lose, gain, or share electrons in order to acquire the stable electron configuration of a noble gas.

      2. Tendency of atoms to want to have eight electrons in their valence shell

   2. s, p, d, f blocks

      1. S: s= sphere shape l= 0

      2. P: p=peanut/dumbbell shape l=1

      3. D: d=clover shape l=2

      4. F: f= complex shape, 3D l=3

   3. Kernel/core vs. valence electrons

      1. valence = outer, easier to lose

      2. kerne/corel = everything else, harder to lose

   4. Noble gas configuration

      1. Takes the last nobel gas and continues configuration from there 

      2. (ex: K = [Ar] 4s1)

   5. Ions

      1. When atoms gain or lose electrons they form a positive or negative charge. 

      2. Mark with a + or -

      3. To make a positive ion = remove electrons 

      4. To make a negative ion = add electrons  

   6. Excited states 

      1. Aufbau & Hund may be violated

      2. Follow pauli exclusion principle

      3. Must have correct number of electrons

      4. Not be in the ground state

      5. Indicate with asterisk (Li*)

   7. Exceptional transition metals

      1. Chromium (Cr)  & Copper (Cu) rows

      2. It is favorable to have a half full or full subshell instead of an almost full or almost half

   8. Isoelectronic atoms and ions

      1. Things that have the same electron configuration (they will only start with neutral noble gasses)

         1. Ex. S^2-, Cl^-, Ar, K^+, C^2+

7. Classification of the elements

   1. Identify location of metals, nonmetals and metalloids

      1. Metals are on the left of representatives, all the transition metals (including actinides and lanthanides)

      2. Metalloids: Staircase between metal and non-metal (7 total)

      3. Non-metals: Hydrogen and the right of the table or staircase. 

   2. Define basic properties of metals, nonmetals and metalloids

      1. Metals: metallic colored, malleable, ductile, conductors of electricity and heat.

      2. Metalloids: Brittle, semiconductor, solid, between non-metal and metal, metallic luster

      3. Non-metal: High ionizations, electronegative, poor conductors , brittle solids, no luster, dull.

   3. Identify group/family names

      1. Group 1: Alkaline metals

      2. Group 2: Alkali earth metals

      3. Groups 3-12: Transition metals

      4. Group 17: Halogens

      5. Group 18: Noble gas

      6. Period 6-7: Lanthanides and Actinides- Rare Earth metals 

8. Periodic trends

   1. Atomic radius

      1. as you go across a period it decreases, as you go down a group it increases

   2. Ionization energy

      1. amount of energy it takes to remove an electron 

      2. As you go across a period it increases, as you go down a group it decreases

      3. b/c if the radius is bigger then it takes less energy to remove b/c it is further from the nucleus

   3. Electron affinity

      1. amount of energy is released to form negative ions

      2. As you go across the group it increases and as you go down a period it decreases

   4. Reactivity

      1. How likely an element is to react and form compounds

      2. Halogens & alkali metals are very reactive (fluorine & francium = most)

      3. Top right & bottom left = strong

      4. Staircase = less reactive than other elements but more reactive than noble gasses

   5. Electronegativity

      1. Indicates the relative ability of an element’s atoms to attract electrons in a chemical bond.

      3. Noble gasses are ignored

      4. Fluorine = most electronegative

      5. As you go down a group it decreases and as you go across a period it increases
         
         

ELECTROSTATICS & CIRCUITS

1. Electrostatics:

1. Electrostatics

   1. The study of electric charges that can be collected and held in one place.

   2. neutral surface & neutral surface = no electrostatic force

2. Static electricity

   1. Static electricity is caused by an imbalance of + & - charges within an atom

   2. Electrons & protons have same magnitude of charges but not same mass

      1. Protons are ~2000x the mass of electrons 

      2. electrons can move more than protons when acted on by an equal force b/c it has less mass & greater acceleration

3. electric charge

   1. When a charged material touches another material it will gain or lose electrons 

4. Polarization

   1. Separating of charges within an object

   2. EX: after rubbing a balloon on your hair it becomes negatively charged, when the - balloon is put on a neutral board it becomes polarized. The negative balloon attracts the protons to the surface of the board touching the balloon and the electrons move to the other side of the atom. 

5. Charging

   1. How does a plastic strip become negatively/positively charged by rubbing?

      1. Rubbing a plastic strip = friction 

      2. If friction provides enough energy = electron transfer

      3. The other material should have a lesser electron affinity than plastic strip = gain electrons

      4. The other material should have a greater electron affinity than plastic strip = lose electrons

   2. Conduction

      1. direct  contact

      2. Actual transfer of electrons

3. Induction

   1. Not direct contact = charged object brought near neutral object

   2. Separation of Charges- charges rearranged (positive and negative charges separated)

6. Coulomb's law

   1. F=kq_1q2r2

   2. k= 8.99 109Nm2c2

   3. Describes the strength of electrostatic forces between two forces, attracted or repelled. 

   4. If the value of the force is positive the two forces are repulsive b/c same sign and if the force is negative they are attractive b/c different signs

7. electric field

   1. E=Fq

      1. Base units e=n/c

   2. Vectors

      1. quantity that show magnitude and direction of the electric field in a specific spot in space

      2. multiple  arrows

      3. electric field vectors are in the same direction as electrostatic force vector when q is positive

   3. field lines

      1. Positive field lines go outward(repel)

      2. Negative field lines go inward(attract)

      3. More of a visual/hypothetical

      4. one  arrow

      5. The proximity of field lines to one another tell you how strong the electric field is

4. Electric field between two plates

8. electrostatic potential energy

   1. The amount of energy it takes to move a charge in an electric field

   2. Work increases electrostatic potential energy

   3. ΔPE_E=Eqd  

   4. When a proton is transferred electrostatic potential energy is positive meaning it is increasing, for electrons it is negative meaning its decreasing

9. electric potential difference

   1. ΔV=kqr

   2. ΔV=Ed

   3. does not depend on the transferred charge

   4. 1. A: the spring has more elastic PE when compressed B: similarly the small charge has more PE when pushed closer to the charged sphere. The increased PE is the result of work input

II. Circuits: a closed path for charge

1. electric current

   1. I=qΔt

2. Ohm's law

   1. V=IR

   2. Relationship between voltage across and current through a battery

3. series & parallel circuits

   1. Series circuits: 

      1. Single Path (electrons have no choice)

      2. Current flows through all resistors

         1. Current of resistors & battery are equal

         2. Sum of the voltage of resistors are equal to the voltage of the battery

   2. Parallel circuits:

      1. Multiple Paths in parallel

   3. Same Voltage the whole way through

      1. Multiple paths (electrons have a choice)

         1. A partial amount of electrons choices in their paths 

         2. Voltage of resistors & battery are equal

         3. Sum of the current of resistors are equal to the current of the battery

4. Parts of Circuits

   1. Electrolytic Cell

      1. made of an electrolyte or salt solution

      2. side w/ bump= +, flat side = -

   2. Battery

      1. Combination of electrolytic cells

      2. 1. long side = positive & short side = negative b/c electrons less mass

   3. Resistor

      1. a two terminal electrical component that regulates the flow of electric current

      2. there is a different code on every resistor

         1. R=AB10C+D%

   4. Ammeter

      1. Measures current amperes

      2. Connected in  series with the element you want to measure (can be anywhere in a series circuit) 

   5. Voltmeter

      1. Measures voltage 

      2. Connected in parallel with the element you want to measure 

   6. Node

      1. Area in a circuit where there is only one element (wire)

5. equivalent resistance

   1. Series

      1. eq>largest resistor

      2. R_eq= R₁ + R₂ + R₃ 

   2. Parallel

      1. eq<smallest resistor

      2. 1/R_eq= 1/(1/R₁ + 1/R₂ + 1/R₃ )

         1. This allows you to treat it as a series circuit so you can use the formula.

6. electric power

   1. The rate at which energy changes

   2. Battery adds energy & resistor takes energy 

      1. P_b= P₁ + P₂ + P₃

   3. P = IV

   4. Resistors only: P = v2R=I2R

III. Formulas

1. Electrical fields

   1. F=kq1q2r2

   2. F=eq

   3. E=fq=pt

   4. W=fd=Eqd

   5. v=Ed

2. Circuits

   1. V=IR

   2. P=VI

   3. P=I2R=V2R

   4. Req(series)= R1+R2+R3…

   5. 1/Req(parallel)= 1R1+1R2+1R3