Wednesday, October 27, 2010

pH Notes and Calculations

http://www.sciencegeek.net/Chemistry/chempdfs/pHCalculations.pdf

Lab 2: Penny Lab: Cohesion/Adhesion

Penny Lab: Post- Lab Analysis

3. Explain what surface tension is.
4. Why were many trials taken and averaged?
5. In this experiment, what was your control group?
6. Identify the independent variable in the experiment.
7. Identify the dependent variable in the experiment.
8. What if the experimental question was "How does sugar affect the surface tension of water?" Describe how you would answer this question using the scientific method. If you have time, you can test this.

Bellringer 7-8

A substance with a pH of 2 is ____.
a. Acidic
b. Basic
c. Caustic
d. Volatile

The water molecule is ______ .

a. polar
b. non-polar
c. bipolar
d. codependent

Water Molecule Notes

http://www.bethel.k12.or.us/schools/teachers/bcollins/IB%20Biology%20files/chemistry%20of%20water.pdf

Tuesday, October 12, 2010

The Water Molecule

This week we will discuss the properties of the water molecule. Due to its structure, the ability of the water molecule to bond with other substances makes it unique and the universal solvent for many substances.

The link will give you an overall view of the water molecule:

http://www.chem1.com/acad/sci/aboutwater.html

SUMMARY OF TRENDS IN THE PERIODIC TABLE

SUMMARY OF TRENDS IN THE PERIODIC TABLE can be found at this site
http://www.avon-chemistry.com/p_table_lecture.html

Summary of Trends

Moving Left --> Right

Atomic Radius Decreases
Ionization Energy Increases
Electronegativity Increases

Moving Top --> Bottom
Atomic Radius Increases
Ionization Energy Decreases
Electronegativity Decreases

Lab 2: We are Family

Objective:

Today's lab will focus on the grouping of families of elements. Their characteristics and behavior are the same but their reactivity towards each other is different. You will be forming compounds with elements from the same family and observe its reaction.

Wednesday, October 6, 2010

Adopt An Element Project

Project Timeframe
Sept 18 Assignment- Begin Reading
Sept 30/Oct 1 Library Research
Due Oct 7


Requirements:
1) Complete an Adopt An Element information sheet. (60% of grade)
You may use a variety of reference sources. Possible ideas are encyclopedias (book
or CD Rom), science encyclopedias, science catalogs, magazines, and/or Internet sites*.
Information sheets must be neat, written in black ink, and contain all the information
requested. You also need to provide a list of your sources on the back of your
information sheet. A minimum of three sources are required.


2) Create an advertisement for your element. (40% of grade)
The advertisement must include the element’s name, symbol, atomic number,
atomic mass, cost, and an advertising slogan that describes one or more of its important
uses. Advertisements must be neat, colorful, and contain all the information listed
above. You may add pictures that relate to your advertisement theme.


Be sure to include:
Ö Element’s symbol
Ö Element’s name
Ö Atomic number
Ö Atomic mass
Ö Ad slogan
Ö Cost
Ö Your name


You may add pictures or
drawings that illustrate
the various uses for your
element.


Your ad must follow
the same format
as this example!
Atomic Number
33 74.9
As
Arsenic
Arsenic’s a sure fire way
to deal with a nasty rat,
It works better than
a mean old cat!
Cost = $3.20 for 1 gram
John Smith
Atomic Mass
Symbol & Name
Slogan
Cost
Name

Sunday, October 3, 2010

Student Conferences This Week

Lab 1: We Are Family

Objective:

Today's lab will focus on the grouping of families of elements. Their characteristics and behavior are the same but their reactivity towards each other is different. You will be forming compounds with elements from the same family and observe its reaction.

Bellringer 6

Match the word to its definition.

Atomic Radius __
Electronegativity (Affinity) __
Ionization Energy __
Reactivity __

A. the amount of energy required to remove the outmost electron. It is closely related to electronegativity

B. an atom's 'desire' to grab another atom's electrons

C. refers to how likely or vigorously an atom is to react with other substances. This is usually determined by how easily electrons can be removed (ionization energy) and how badly they want to take other atom's electrons (electronegativity) because it is the transfer/interaction of electrons that is the basis of chemical reactions

D. an indication of the atom's volume

Bellringer 5

Which element is in Group 3, Period 4?

Which of the following element is NOT a metal?
a. Li
b. Mg
c. Al
d. Br

Which of the following element is NOT found in air?
a. C
b. O
c. Ne
d. H

Period Table Summary of Trends

SUMMARY OF TRENDS IN THE PERIODIC TABLE can be found at this site
http://www.avon-chemistry.com/p_table_lecture.html

Summary of Trends

Moving Left --> Right

Atomic Radius Decreases
Ionization Energy Increases
Electronegativity Increases

Moving Top --> Bottom
Atomic Radius Increases
Ionization Energy Decreases
Electronegativity Decreases

Period Table...More Trends

Review
Period - a row of elements on the periodic table. Remember that sentences are written in rows and end with a period.

Group - a column of elements on the periodic table. Remember that group is spelled group and groups go up and down.

Atomic Radius - Atomic radius is simply the radius of the atom, an indication of the atom's volume.

Period - atomic radius decreases as you go from left to right across a period.
Why? Stronger attractive forces in atoms (as you go from left to right) between the opposite charges in the nucleus and electron cloud cause the atom to be 'sucked' together a little tighter.

Group - atomic radius increases as you go down a group.
Why? There is a significant jump in the size of the nucleus (protons + neutrons) each time you move from period to period down a group. Additionally, new energy levels of elections clouds are added to the atom as you move from period to period down a group, making the each atom significantly more massive, both is mass and volume.

Electronegativity - Electronegativity is an atom's 'desire' to grab another atom's electrons.

Period - electronegativity increases as you go from left to right across a period.
Why? Elements on the left of the period table have 1 -2 valence electrons and would rather give those few valence electrons away (to achieve the octet in a lower energy level) than grab another atom's electrons. As a result, they have low electronegativity. Elements on the right side of the period table only need a few electrons to complete the octet, so they have strong desire to grab another atom's electrons.

Group - electronegativity decreases as you go down a group.
Why? Elements near the top of the period table have few electrons to begin with; every electron is a big deal. They have a stronger desire to acquire more electrons. Elements near the bottom of the chart have so many electrons that loosing or acquiring an electron is not as big a deal. This is due to the shielding affect where electrons in lower energy levels shield the positive charge of the nucleus from outer electrons resulting in those outer electrons not being as tightly bound to the atom.

Ionization Energy - Ionization energy is the amount of energy required to remove the outmost electron. It is closely related to electronegativity.

Period - ionization energy increases as you go from left to right across a period.
Why? Elements on the right of the chart want to take others atom's electron (not given them up) because they are close to achieving the octet. The means it will require more energy to remove the outer most electron. Elements on the left of the chart would prefer to give up their electrons so it is easy to remove them, requiring less energy (low ionization energy).

Group - ionization energy decreases as you go down a group.
Why? The shielding affect makes it easier to remove the outer most electrons from those atoms that have many electrons (those near the bottom of the chart).

Reactivity - Reactivity refers to how likely or vigorously an atom is to react with other substances. This is usually determined by how easily electrons can be removed (ionization energy) and how badly they want to take other atom's electrons (electronegativity) because it is the transfer/interaction of electrons that is the basis of chemical reactions.

Metals

Period - reactivity decreases as you go from left to right across a period.

Group - reactivity increases as you go down a group
Why? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity.Non-metals

Period - reactivity increases as you go from the left to the right across a period. Group - reactivity decreases as you go down the group.
Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron.

Ionic Radius vs. Atomic Radius

Metals - the atomic radius of a metal is generally larger than the ionic radius of the same element.
Why? Generally, metals loose electrons to achieve the octet. This creates a larger positive charge in the nucleus than the negative charge in the electron cloud, causing the electron cloud to be drawn a little closer to the nucleus as an ion.

Non-metals - the atomic radius of a non-metal is generally smaller than the ionic radius of the same element.
Why? Generally, non-metals loose electrons to achieve the octet. This creates a larger negative charge in the electron cloud than positive charge in the nucleus, causing the electron cloud to 'puff out' a little bit as an ion.

Melting Point

Metals - the melting point for metals generally decreases as you go down a group.

Non-metals - the melting point for non-metals generally increases as you go down a group.

http://www.geocities.com/CapeCanaveral/Lab/4097/chem/chap4/periodictrends.html
from

Bellringer 4

The three major groups of elements on the periodic table are:

a. Metals, non-metals, gases
b. Metals, mettaloids, gases
c. Metals, alkalines, lactinides
d. Metals, alkaline earth metals, gases

Bellringer 3

Which statement is true?

a. There are 18 groups and 7 periods on the periodic table.
b. There are 18 periods and 7 groups on the periodic table.
c. There are 18 classes and 7 kingdoms on the periodic table.
d. There are 18 families and 7 groups on the periodic table.