PERIODIC TRENDS

On Tuesday we spent time going over the work sheets, or test review- and here are the answers.

Section 6.3

1. Atomic radii cannot be measured directly because the electron cloud surrounding the nucleus does not have a clearly defined
c. Outer edge

2. Which diagram best represents the group and period trends in atomic radii in the periodic table?
c. diagram c

3. The general trend in the radius of an atom moving down a group is partially accounted for by the
d. Shielding of the outer electrons by inner electrons.

4. A------ is an atom, or bonded group of atoms, that has a positive or negative charge.
b. Ion

5. An atom becomes negatively charged by
a. Gaining an electron

6. Which diagram best represents the relationship between the diameter of a sodium atom and the diameter of a positive sodium ion?
a. Diagram a

7. What is ionization energy?
Energy required to remove an electron from a gaseous form

8. Explain why an atom with a high ionization-energy value is not likely to form a positive ion?
A high ionization-energy value indicates that the atom has a strong hold on it’s electron and is not likely to lost an outer electron and form a positive ion

9. What is the period trend in the first ionization energies? Why?
The 1st ionization energies generally increases as you move left to right across a period. The increased nuclear change of each successive element produces and increased hold on the valence electrons.

10. What is the group trend in the first ionization energies? Why?
The 1st ionization energies generally decrease as you move down a group because atomic size increases down a graph, the valence electrons are far then from the nucleus and there for less strongly attached to the nucleus as a result, less energy is required to remove the valence electron.

11. State the Octet rule.
Atoms tend to gain, lose, or share electron to a quire a full set of eight valence electron.

12. What does the electro negativity of an element indicate?
Its atom’s ability to attract electron in a chemical bond
13. What are the period and group trends in electronegativities?
Increases left to right across a period and decreased as you move down a group.

Answers for the work sheets

ELECTRONEGATIVITY AND POLARITY

Section 9.5

1. What is the meaning of the electronegativity?
The tendency of an atom to attract highest electronegativity electrons

2.Which element has the? What is the numerical value? What are the name and group number of the chemical family that has the highest overall electronegativity?
Fluorine; F; 3.98; halogens; group 7A

3. Which element has the lowest electronegativity? What is the numerical value? What are the name and group number of the chemical family that has the lowest overall electronegativity
Francine; 0.7; alkaline metals; group 1A

4. What general tend in electronegativity do you note going down a group? Across a period?
Decreasing – increasing

5. How are the electronegativity values used to determine the type of bond that exists between two atoms?
Electrons are subtracted.

6. Ionic compounds are usually soluble in polar substances- True

7. In a covalent molecular compound, the attraction between molecules tends to be strong- False

8. Unequal sharing of electrons between two bonded atoms always indicates
c. A polar covalent bond

9. When electronegativity of two bonded atoms differ greatly, the bond is
d. ionic

10. What is the electronegativity difference that usually is the dividing line between covalent and ionic bonds
b. 1.7

11. The Symbol δ is placed next to which of the following
a. The less electronegativity atom in a polar covalent bond

12. A nonpolar covalent bond is one in which
c. Electrons are shared equally.

13. Molecules containing only polar covalent bonds
b. May or May not be polar

14. What factor other than electronegativity determines whether a molecule as a whole is polar or not?
b. its geometry

15. Which of the following correctly describes the compound water, H₂O?
d. Polar overall, which polar covalent bonds

16. Which of the following correctly describes the compound carbon tetrachloride, CCl₄?
a. Nonpolar overall, with polar covalent bonds

17. A molecule of ammonia, NH₃, is
d. polar because there is an electronegativity difference and the molecule is trigonal pyramidal.

March 19, 2007

Okay so today in class, we went over a few sheets that were given to us before the weekend. First of all, we went over the Atomic Worksheet: Trends in the Periodic table. We basically just answered the questions, and as for number 1 & 6, we drew it out on the smart board. We also went over the worksheet based on Using the Periodic Table (Chapter 6). And finally, we went over a few of the answers for Electrons in Atoms. We didn't quite finish, but we got up to the fourth page.

But anyway, just a reminder ... there is a test on Wednesday, so get ready and start studying!

Monday, March 19 Notes

Periodic table trends and handout explanation

Sean here sorry for the late post, took me a while to figure out my password, anyway for thoses who missed what was done today we discussed the electronegativity of elements or if you will their ability to attract electrons by way of chemical bonding. I suggest you take out out your table of electronegativity, that would be that sheet package you got earlier in the year. As you can see fluorine has a electronegativity of 4.10 making it the most electronegative element on the table, if you do not see this you might have the wrong sheet. For those who missed today/yesterday's class take out one of the blank periodic tables received today, each element will have a subshell as seen in the electron configuration sheet (the one with the arrows in the boxes) this being said every element in groups I and II will have subshell on the outside with the exception of hydrogen and helium who are labeled as 2S. So if you want you can colour in the S, D,P and F sections, for instance as said before I and II should be labeled as S so fill in those columns along with 3 to 12 as D , 13 to 18 as P and finally the lanthanides and actinides (the bottom ones) as F, the colours you have to use won't matter as long as you can distinguish between them. Now for the second blank sheet you will need to point out a series of things. Now as we move from left to right on the electronegativites table we find that obviously the electronegativity is increasing so on the blank table draw an arrow pointing right and label it as eletronegativity increasing, the eletronegativity also decreases as you go down a group so you can label that. Now we go onto ionization energy AKA the energy needed for a element to take an electron from a gaseous atom. I won't go into a deep discussion about this so remember high ionization energy equal low possibility to form a positive ion and a low one means it will lose its outer electron with ease, so left to right on the table again draw a arrow pointing right and write ionization energy increases, this goes like the electronegativity going down a group, so arrow down ionization decreases. This same increase goes for the negative ions also, so left to right increase in ions you get the point anyhow lastly we go to atomic radius, now what would this be, atomic radius is the distance between the atoms nucleus to its outer most stable orbital. The atomic radius can be found by cutting the distance between the nuclei with the nuclei of a similar atom in half. You might not be able to find the distance of two nuclei yourself, apparently it takes equipment which is just out of the common student's hands to find said distance. Atomic radius is similar to ionic radius in the sense of distance between two things hence the radius part but ionic radius is the distance between cations and anions in crystal ions. Back to the table draw two arrows going down a group, one with atomic radius increasing and ionic radius increasing. Thus the table is pretty much done.

Reminder: test on wednesday
review: Do it, I guarantee it will not bite.
The scriber in line out of a random pick will be ...kayyy, due to user names of course it's random, good luck with the scribe and for those who haven't scribed the wait to be picked is worse than the actual scribe.

My notes of atomic structure

Hi ms K.

i'm very impressive by the ways you taught the electrons configuration through music which's incretible exprience ihave never heard before. what i'm interested to know is that

Electrons configurations

1. show electrons in an element and their energy level and sublevel.

For example Nitrogen (atomic number 7)
1s² 2s² 2p³ the main principle of aufbau in electrons configuration is to fill with the lowest energy state. In order to represent an atom's electron configuration you should consider two convenient methods. one method is known as an orbital diagram. It includes a box for each of the atom's orbitals.An empty box represents an unoccupied orbital, a box containing a single up arrow represents an orbital with one electron, and a box containing both up and down arrows represents a filled orbital.
Reminder: Test on Atomic Structure is Tuesday, March 20.
Reminder: Finish activity sheet-Ch.5 Study Guide for tomorrow
The next scribe will be Sean

Orbital Diagrams/Electron Configurations

in class yesterday we went over the quantum mechanical model. we discused how it is similar and how it is different from the Bohr model. we also went over contributors to the Q.M.M. like G.P Thomson. We corrected the activity sheet on Q.M.M.

we looked at something new about how to do electron configuration, the arrangement of electrons. we looked at the three principles, aufbau principle, Hund's rule and Pauli exclusion principle. Check the handouts for more information on this topic.

Today's Notes

Scribe Post

Yesterday, we were asked to complete two worksheets, that were given by the SUB. The two questions were 1 through 8 on the back of the "The Bohr Model of Hydrogen Atom", and to complete the worksheet called "Quantum Mechanical Model of the Atom Worksheet" the answers are in the worksheet with the Smart people on it, but we were not given information about 2 of the Smart people, Wolfgang Pauli and Werner Heisenberg. So i didn't hand in the worksheets, though they were due by the end of the class. So I feel that i should tell the right answers for the 2 Wolfgang Pauli: Only 1 electron in each energy level state is allowed, and Werner Heisenberg: Suggested the dual nature of matter (wave/particle). He placed a fundamental limitation on how precisely we can know both the location and the momentum of any object. Sorry This is late, and Eddie knows he is scribe next anyways.

Atomic Structure

hello...

Note: the atomic emission spectrum of an element is the set of frequencies of the electromagnetic waves emitted by atoms of the element. it is different from visible spectrum because visible spectrum is a continuous range of colours while in atomic emission spectrum consists of several individual lines of colour.Each element's atomic emission spectrum is unique and can be used to determine if that element is part of an unknown compound.

at the beginning of class, we looked at the atomic emission spectrum of the noble gasses. I was having trouble seeing the spectrum and only saw few of them...

starting from left to right...

for hydrogen, I saw red, blue and purple
Argon = red, orange, yellow, green, blue and purple
Iodine = red yellow green
Helium = red, orange, yellow, green
for the last two elements we did........i didn't saw any spectrum......hope you got 'em ^_^

after that "mini-light" show, we corrected our homework that was given out last Friday "Atomic Structure Assignment 1"

here are the questions and answers (front side)

1. define the terms wavelenght and frequency.
- wavelenght is the distance between two crest - frequency is the number of cycles that pass a point in 1 second.

2. arrange the following types of electromagnetic radiation in order of increasing wave lenght: Ultraviolet waves, microwaves, radio waves and X rays.
- X rays, Ultraviolet waves, microwaves and radio waves

3. state which type of electromagnetic energy--ultraviolet light or infrared light--has the a) shorter wave lenght b) higher frequency c) lower energy
- a) ultraviolet light b) ultraviolet light c) infrared light

4. describe the difference between a continuous spectrum and a line spectrum.
- continuous spectrum is a pattern of colours - line spectrum is a pattern of single line

5. hydrogen's emission spectrum has 4 lines on it. what does each line represent?
- it represent an electron falling 1 energy level to the next energy level

6. what is a line spectrum and how is it produced?
- line spectrum = pattern of single line, produced when light consists of only a few distinct wavelengths pass through a spectroscope

7. describe how spectroscopy can be used to identify a gas.
- used to identify ions in a solution, specific ions give off a characteristic colour by passing the light from flam tests.

8. write a paragraph that explains the chemistry behind a fireworks display, include the ground state, excited state, Bohr model of atom, flame test.
- DUE THIS WEDNESDAY!!

(back side)

2. which part of the electromagnetic spectrum do the atomic emission spectra show?
- the visible spectrum

3. would the atomic emission spectrum for each sample change if you repeated the procedure?
- No, because each element has its own atomic emission spectrum and all elements has different spectrum

4. what does each line in an atomic emission spectrum represent?
- it represent the energy of electrons


I choose you....................ALLEN to be the next scribe!

vehcsur out..........

Atomic Structure

The test was handed back on Friday. We also started the Atomic Structure Unit; worksheets were handed-out.



Electromagnetic Energy - Light Energy

Light Energy is a form of energy that is transferred by radiation and is thought to move in the forms of waves.

Frequency - cycles per unit in time. (eg. in lightwave - the # of cycles pass a point in one second)



Wavelength is the distance between the crest or troughs. The wavelength of visible light is mostly measured in nanometres.

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Line Spectrum is a spectrum in which energy is concentrated at particular wavelengths; produced by excited atoms and ions as they fall back to a lower energy level.

Continuous Spectrum is when all the wavelengths of lights are represented. Line Spectrum on the other hand, is a distinct of coloured lines rather than a rainbow. In an element, the line spectrum is unique in each ones; no two elements have the same atomic emission spectrum. It's like a fingerprint.

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I hope these helped you with the Assignment. =)

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Oh yeah. Next Scribe will be Ruschev.