CHEM101 Lecture Notes - Lecture 3: Electron Density, Bohr Radius, Resultant Force

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ambersea-lion631

5 Oct 2018

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University of Alberta

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Chemistry

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CHEM101

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Sai Yiu

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CHEM101 Lecture 2: Bohr's Atomic Model

CHEM101 Lecture Notes - Lecture 3: Electron Density, Bohr Radius, Resultant Force

CHEM101 Lecture 4: Periodic trends

Document Summary

Electron configuration and the periodic table prelecture notes. This is true only when there is one electron. Energy of atomic orbitals in a hydrogen atom (with one electron) Quantum mechanical calculations give three quantum numbers (n, l and ml). Because electrons spin along an axis, there is yet another quantum number: the electron spin quantum number, ms, needs to be introduced. Such spinning of electrical charge generates its own magnetic field. Electron-spin quantum number (ms) can have two possible values: Thus, it takes three quantum numbers to define an atomic orbital but we need four quantum numbers to identify an electron in an atom. 0,1,2,3, (n-1) orbital shape (s, p, d, f) +1/2, -1/2 direction of electron spin an atom. Although the electron density is highest around the nucleus, it does not mean it has the greatest probability of being found around the nucleus. Recall: electron density of the orbital (s orbitals as shown below):

Related Questions

provided to determine AH rxn for the following reaction: urf (klimol) CH4(g) + 3 Cl2(g) â CHCI3() + 3 HCI(g) airrxn-? A)-151 kJ B)33SkJ C) +662kJ D) +117kJ E)-217 kJ A) 4.1 atm B) 5.0 atm c) 6.4 atm D)1.1 atm E) 2.3 atm kg) of the copper sample if the specific heat capacity of copper is 0 CH4(g) 75 CHCI3() -134 HCI(g) -92 8) What pressure will 14.0 g of CO exert in a 3.5 L container at 75 C? 9) A sample of copper absorbs 43.6 kJ of heat, resulting in a temperature rise of 50.0Â°C, determine the mass (in .385 J/g C A) 226 kg B) 0.235 kg C)6.64 kg D) 119kg E)5.10 kg 10) Which of the following processes is exothermic? A) the ionization of a melting snow atom B) the breaking of a boiling of water bond C) the boiling of water D) the condensation of water E) All of the above processes are exothermic 11) Calculate the energy of the red light emitted by a neon atom with a wavelength of 703.2 nm. B)4.27 x 10-19J C) 2.34 x 10-19J D)6.45 x 10-19J E) 2.83 x 10-19J A)3.54 Ã 10-19J 12) Identify the color of a flame test for potassium D) yellow A) violet B) red C) white E) blue 13) Which of the following statements is TRUE? A) The emission spectrum of a particular element is always the same and can be used to identify the element. B) Part of the Bohr model proposed that electrons in the hydrogen atom are located in "stationary states" or particular orbits around the nucleus. C) The uncertainty principle states that we can never know both the exact location and speed of an electron. D) An orbital is the volume in which we are most likely to find an electron. E) All of the above are true. 14) Calculate the wavelength of an electron (m-9.11 x 10-28 g) moving at 3.66 Ã 106 m/s. A)1.99 x 10-10m B)5.03 x 10-10 m C) 1.81Ã10-10 m D)5.52 Ã 10-9 m E) 2.76 Ã 10-9 m 15) Which of the following quantum numbers describes the shape of an orbital? A) principal quantum number B) magnetic quantum number C) spin quantum number D) SchrÃ¶dinger quantum number E) angular momentum quantum number 16) Determine the energy change associated with the transition from n = 2 to n-5 in the hydrogen atom. A)-218Ã10-19J B)+654 Ã 10-19 J C) +4.58 x 10-19 J D)-1.53 x 10-19 J E) +3.76 Ã 10-19J 17) If two electrons in the same atom have the same value of I, they are A) in the same sublevel, but not necessarily in the same level. me level, but different sublevel. C) in the same orbital. D) in different levels and in different shaped orbitals. E) none of the above.

Practice problems for exam 2 ______________

Useful Information:

h=6.626Ã10-34JÂ·s.; c=3.0Ã108 m/sec; E=hï® ; E= hc , ï¬ = h/mv; 1J = 1 kg-m2/s2 ï¬

mass of electron = 9.11 Ã 10-28 g, ïE= q + w ; 1 cal = 4.184 Joules Please Show all Work

1. Which of the following substances have standard heats of formation that are equal to zero by definition (circle your answers): H2(g), H(g), O3(g), H2O(s), H2O(l), Hg(l), Hg(s), Hg(g).

2. Limestone stalactites are formed in the reaction: Ca2+(aq) + HCO3-(aq) ï CaCO3(s) + CO2(g) +

H2O(l)
If one mole of CaCO3 is produced at 298 K under one atmosphere of pressure, the reaction performs 590 calories of expansion work, pushing back the atmosphere as CO2 is formed. At the same time, 9310 calories of heat are absorbed from the environment. What is ïE in Kcal/mole for CaCO3.

3. What is the minimum wavelength of light in AÌ (1 AÌ = 10-8 cm) needed to provide enough energy per quantum to rupture the chemical bond in hydrogen iodide (HI). The bond dissociation energy of HI is 71.4 Kcal/mole.

4. Sketch the shape and orientation of the following types of orbitals: s, px, dxy, dz2, dx2-y2

5. Give the values of (n) , (l) and (ml) for each orbital in the 4p subshell.

6. Write the complete electron configuration for the following: Ti 2+_____________________________________ Cr_______________________________________

N______________________________________

7. Calculate the standard enthalpy of formation ( ï Ho) for diamond from graphite [i.e. C (graphite) ï C (diamond)] given that:

C (graphite) + O2 ï CO2 (g) ( ï Ho = -393.5 KJ/mole) C (diamond)] + O2 ï CO2 (g) ( ï Ho = -395.4 KJ/mole)

If 1.0g of graphite is converted to diamond, what is the energy change? Is this an endothermic or exothermic reaction?

8. An 160 pound astronaut on his way to Mars is buzzing along at 10,000 miles per hour. (a) Express his weight in grams (one pound = 454 grams) so that you can calculate the astronautâs wavelength (1mile/hour = 44.7 cm/sec)

(b) Suppose the astronaut detects outside his spacecraft a proton (m=1.7 x 10-24 g) from a âsolar windâ moving at exactly the spacecraft velocity. What is the proton wavelength is in AÌ (1 AÌ = 10-8 cm.

9. What is the maximum number of electrons that can occupy each of the following subshells? a) 3d_________________ b) 1s____________________ c) 2p ____________________

10. Identify the element represented by the following electronic configuration.

a) [Ne] 3s2____________________

b) What is the electron configuration for the first excited state of this atom.______________

11. Determine the number of valence electrons for each element.
(a) Br___________ (b) Na _________ (c) Sn __________

12. 175 g of Fe at 15.0oC is mixed with 225 g of H2O at 95.0oC. What is the final temperature of the mixture? The specific heats of iron= 0.448 J/g oC and water = 4.184 J/g oC). (keep in mind the following: heat gained + heat lost = 0 and q=mass x heat capacity x ïT)

13. (5 pts) Calculate values of ÎHrxn for the following reactions: CS2(g) + 3O2(g) ï® CO2(g) + 2SO2(g)

The heat of formation for the following substances is given in kJ/mol:

CS2 CO2 SO2 117.4 -393.51 -296.83

14. (6 pts) Use the electron configuration of Li and Be and determine which element has the greatest second ionization energy. Defend your answer.

15. Mark beside each of the following processes either âexoâ or âendoâ according to whether you think the process will release heat or absorb heat.

a. Ca(g) ï Ca(g)+2 + 2e-
b. I(g)+1e-ï I(g)-1
c. Ca(g)+2 + S(g)-2 ï CaS(s) d. I2(g)ï 2I(g)

( ) ( ) ( ) ( )

16. (6 pts) In each of the following pairs, which of the two species is larger?
a) O-2 or Na+ b) Ti+4 or Ti+2 c) B or C d) N or N-3

17. Write down the Lewis dot structure for the following (a) N_______________ (b) Ne________________

18. THE BORN HABER CYCLE: I may have a problem on the Born Haber cycle. Please check my lecture notes to see how to set up the process and then calculate the lattice energy from the various thermodynamic quantities such as in the NaCl example below;

ï H ï¯ f NaCl = -411KJ

Na(s) ï® Na(g) ï H =108KJ
1â2 Cl2 ï® Cl(g) ï H = 122KJ Ionization Energy of Na ï H = 496 KJ Electron affinity of Cl ï H = -349KJ

CHEM101 Lecture Notes - Lecture 3: Electron Density, Bohr Radius, Resultant Force

CHEM101 Lecture 2: Bohr's Atomic Model

CHEM101 Lecture Notes - Lecture 3: Electron Density, Bohr Radius, Resultant Force

CHEM101 Lecture 4: Periodic trends

Document Summary

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