Question

ch.6 worksheet #2
identify the following peoples discoveries/models/theories as we have discussed in class.

1. aristotle / democritus
2. john dalton (2)
3. henri becquerel
4. j.j. thomson (2)
5. marie & pierre curie
6. max planck
7. robert millikan
8. ernest rutherford (2)
9. niels bohr
10. louis de broglie
11. wolfgang pauli
12. werner heisenberg
13. erwin schrödinger
14. james chadwick

complete the following frequency problems. use the formula: 2.9979210^8m/s = c = λ ν.

1. a wave is 554m; find its frequency.
2. a wave is 84200000hz; find its wavelength.
3. a wave is 500nm. whats its frequency?
4. a 4.2*10^13hz wave has what wavelength?
5. a wave is 450nm; find its frequency.
6. a wave is 9.63*10^19hz; find its wavelength.
7. a wave is 64cm; find its frequency.
8. a wave is 8.6*10^15hz; find its wavelength.

find the number of protons, neutrons, and electrons in the following elements. round the atomic masses to whole numbers to do these problems.

1. pr p = _, n = _, & e = ___
2. v p = _, n = _, & e = ___
3. b p = _, n = _, & e = ___
4. mn p = _, n = _, & e = ___
5. te p = _, n = _, & e = ___
6. i p = _, n = _, & e = ___

Explanation:

Step1: Recall scientific contributions

For the first part, recall the well - known scientific discoveries and models associated with each scientist.

Step2: Use wave - speed formula

For frequency and wavelength problems, use the formula $c=\lambda
u$, where $c$ is the speed of light, $\lambda$ is the wavelength and $
u$ is the frequency. Rearrange the formula as needed to solve for either $
u$ or $\lambda$.

Step3: Use atomic number and mass relationships

For proton, neutron and electron problems, recall that the atomic number ($Z$) is equal to the number of protons ($p$) and the number of electrons ($e$) in a neutral atom. The number of neutrons ($n$) is calculated as $n = A - Z$, where $A$ is the atomic mass.

Answer:

1. Aristotle: Believed matter was made of earth, air, fire and water; Democritus: Proposed the concept of atoms.
2. John Dalton: Dalton's atomic theory (atoms are indivisible, elements consist of identical atoms, etc.).
3. Henri Becquerel: Discovery of radioactivity.
4. J.J. Thomson: Discovery of the electron; Plum - pudding model of the atom.
5. Marie & Pierre Curie: Discovery of radium and polonium; Work on radioactivity.
6. Max Planck: Quantum theory (energy is quantized, $E = h

u$).

1. Robert Millikan: Oil - drop experiment to measure the charge of an electron.
2. Ernest Rutherford: Gold - foil experiment; Nuclear model of the atom.
3. Niels Bohr: Bohr model of the atom (electrons in quantized orbits).
4. Louis de Broglie: Wave - particle duality (matter has wave - like properties, $\lambda=\frac{h}{p}$).
5. Wolfgang Pauli: Pauli exclusion principle (no two electrons in an atom can have the same set of quantum numbers).
6. Werner Heisenberg: Heisenberg uncertainty principle ($\Delta x\Delta p\geq\frac{h}{4\pi}$).
7. Erwin Schrödinger: Schrödinger equation (describes the wave - function of a quantum system).
8. James Chadwick: Discovery of the neutron.

1. Given $\lambda = 555nm=555\times10^{- 9}m$, $c = 2.99792\times10^{8}m/s$, from $c=\lambda

u$, $
u=\frac{c}{\lambda}=\frac{2.99792\times10^{8}}{555\times10^{-9}}\approx5.40\times10^{14}Hz$.

1. Given $

u = 842000000Hz$, from $c=\lambda
u$, $\lambda=\frac{c}{
u}=\frac{2.99792\times10^{8}}{842000000}\approx0.356m$.

1. Given $\lambda = 500nm = 500\times10^{-9}m$, $

u=\frac{c}{\lambda}=\frac{2.99792\times10^{8}}{500\times10^{-9}}=5.99584\times10^{14}Hz$.

1. Given $

u = 4.2\times10^{13}Hz$, $\lambda=\frac{c}{
u}=\frac{2.99792\times10^{8}}{4.2\times10^{13}}\approx7.14\times10^{-6}m$.

1. Given $\lambda = 450nm=450\times10^{-9}m$, $

u=\frac{c}{\lambda}=\frac{2.99792\times10^{8}}{450\times10^{-9}}\approx6.66\times10^{14}Hz$.

1. Given $

u = 9.63\times10^{19}Hz$, $\lambda=\frac{c}{
u}=\frac{2.99792\times10^{8}}{9.63\times10^{19}}\approx3.11\times10^{-12}m$.

1. Given $\lambda = 64cm = 0.64m$, $

u=\frac{c}{\lambda}=\frac{2.99792\times10^{8}}{0.64}\approx4.68\times10^{8}Hz$.

1. Given $

u = 8.6\times10^{15}Hz$, $\lambda=\frac{c}{
u}=\frac{2.99792\times10^{8}}{8.6\times10^{15}}\approx3.49\times10^{-8}m$.

1. Pr (Praseodymium), atomic number $Z = 59$, so $p = 59$, atomic mass $A\approx141$, $n=A - Z=141 - 59 = 82$, $e = 59$.
2. V (Vanadium), $Z = 23$, $p = 23$, $A\approx51$, $n=A - Z=51 - 23 = 28$, $e = 23$.
3. B (Boron), $Z = 5$, $p = 5$, $A\approx11$, $n=A - Z=11 - 5 = 6$, $e = 5$.
4. Mn (Manganese), $Z = 25$, $p = 25$, $A\approx55$, $n=A - Z=55 - 25 = 30$, $e = 25$.
5. Te (Tellurium), $Z = 52$, $p = 52$, $A\approx128$, $n=A - Z=128 - 52 = 76$, $e = 52$.
6. I (Iodine), $Z = 53$, $p = 53$, $A\approx127$, $n=A - Z=127 - 53 = 74$, $e = 53$.