Monday, September 28, 2009
Lab Journals Check
Sunday, September 27, 2009
Library Lab Days
1st Six Weeks Exam
Mixtures, Compounds and Elements
Periodic Table
Atomic Math
Atomic Theory
TAKS Benchmark
Bellringer 13
I. Water is a polar molecule.
II. Water dissolves other polar substances.
III. Water has one positive and one negative end.
IV. Water is known as the universal solvent.
a. I, II
b. II, III
c. I, II, III
d. I, II, III, IV
The Water Molecule
The link will give you an overall view of the water molecule:
http://www.chem1.com/acad/sci/aboutwater.html
Thursday, September 24, 2009
Lab 4: "We are Family"
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 12
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
Monday, September 21, 2009
Bellringer 11
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
Summary of Trends in the Periodic Table
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
Periodic Table Vocabulary
Isoelectronic Elements: are elements that have the same electron configuration.
Periodic Law: The properties of the elements are a periodic function of their atomic numbers.
Periodic Table: A pictorial arrangement of the elements based upon their atomic numbers and electron configurations.
Transition Element: An element whose highest energy electron is in the d orbital.
Lanthanoid Series: Fourteen elements beginning with lanthanum in which the highest energy electrons to be in the 4f sublevel.
Actinoid Series: Fourteen elements beginning with actinium in which the highest energy electrons to be in the 5f sublevel.
Period: A horizontal row on the periodic table.
Group: The elements of a vertical column in the periodic table.
Octet Rule: An especially stable arrangement of four pairs of electrons in the outer energy level of an atom.
Family: The elements composing a vertical column of the periodic table.
Metal: An element that tends to lose electrons in chemical reactions.
Nonmetal: An element that tends to gain electrons in chemical reactions.
Metalloid: An element that has properties characteristic of a metal and a nonmetal.
Period Table of Element....More trends....
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.
from http://www.geocities.com/CapeCanaveral/Lab/4097/chem/chap4/periodictrends.html
Friday, September 18, 2009
Bellringer 10
a. Metals, non-metals, gases
b. Metals, mettaloids, gases
c. Metals, alkalines, lactinides
d. Metals, alkaline earth metals, gases
Wednesday, September 16, 2009
In Class Assignment
Bellringer 9
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.
Tuesday, September 15, 2009
Color Coding the Periodic Table
Student Information Sheet
The Periodic Table is a list of all the known elements. It is organized by increasing atomic number. There are two main groups on the periodic table: metals and nonmetals. The left side of the table contains elements with the greatest metallic properties. As you move from the left to the right, the elements become less metallic with the far right side of the table consisting of nonmetals. The elements in the middle of the table are called “transition” elements because they are changed from metallic properties to nonmetallic properties. A small group whose members touch the zigzag line are called metalloids because they have both metallic and nonmetallic properties.
The table is also arranged in vertical columns called “groups” or “families” and horizontal rows called “periods.” Each arrangement is significant. The elements in each vertical column or group have similar properties. Group 1 elements all have the electron in their outer shells. This gives them similar properties. Group 2 elements all have 2 electrons in their outer shells. This also gives them similar properties. Not all of the groups, however, hold true for this pattern. The elements in the first period or row all have one shell. The elements in period 2 all have 2 shells. The elements in period 3 have 3 shells and so on.
There are a number of major groups with similar properties. They are as follows:
Hydrogen: This element does not match the properties of any other group so it stands alone. It is placed above group 1 but it is not part of that group. It is a very reactive, colorless, odorless gas at room temperature. (1 outer level electron)
Group 1: Alkali Metals – These metals are extremely reactive and are never found in nature in their pure form. They are silver colored and shiny. Their density is extremely low so that they are soft enough to be cut with a knife. (1 outer level electron)
Group 2: Alkaline-earth Metals – Slightly less reactive than alkali metals. They are silver colored and more dense than alkali metals. (2 outer level electrons)
Groups 3 – 12: Transition Metals – These metals have a moderate range of reactivity and a wide range of properties. In general, they are shiny and good conductors of heat and electricity. They also have higher densities and melting points than groups 1 & 2. (1 or 2 outer level electrons)
Lanthanides and Actinides: These are also transition metals that were taken out and placed at the bottom of the table so the table wouldn’t be so wide. The elements in each of these two periods share many properties. The lanthanides are shiny and reactive. The actinides are all radioactive and are therefore unstable. Elements 95 through 103 do not exist in nature but have been manufactured in the lab.
Group 13: Boron Group – Contains one metalloid and 4 metals. Reactive. Aluminum is in this group. It is also the most abundant metal in the earth’s crust. (3 outer level electrons)
Group 14: Carbon Group – Contains on nonmetal, two metalloids, and two metals. Varied reactivity. (4 outer level electrons)
Group 15: Nitrogen Group – Contains two nonmetals, two metalloids, and one metal. Varied reactivity. (5 outer level electrons)
Group 16: Oxygen Group – Contains three nonmetals, one metalloid, and one metal. Reactive group. (6 outer level electrons)
Groups 17: Halogens – All nonmetals. Very reactive. Poor conductors of heat and electricity. Tend to form salts with metals. Ex. NaCl: sodium chloride also known as “table salt”. (7 outer level electrons)
Groups 18: Noble Gases – Unreactive nonmetals. All are colorless, odorless gases at room temperature. All found in earth’s atmosphere in small amounts. (8 outer level electrons)
Color Coding the Periodic Table
Student Worksheet
This worksheet will help you understand how the periodic table is arranged. Your teacher will give you a copy of the periodic table to color. Using map pencils, color each group on the table as follows:
1. Color the square for Hydrogen pink.
2. Lightly color all metals yellow.
3. Place black dots in the squares of all alkali metals.
4. Draw a horizontal line across each box in the group of alkaline earth metals.
5. Draw a diagonal line across each box of all transition metals.
6. Color the metalloids purple.
7. Color the nonmetals orange.
8. Draw small brown circles in each box of the halogens.
9. Draw checkerboard lines through all the boxes of the noble gases.
10. Using a black color, trace the zigzag line that separates the metals from the nonmetals.
11. Color all the lanthanides red.
12. Color all the actinides green.
When you are finished, make a key that indicates which color identifies which group.
Monday, September 14, 2009
Adopt An Element Project
Introduction to the Periodic Table
Bellringer 8
Sunday, September 13, 2009
Atomic Math Games, Periodic Table and Videos
Friday, September 11, 2009
History of Development of the Atomic Theory
http://www2.gsu.edu/~mstjrh/atomictheory.html
Dalton's Atomic Theory
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) All atoms of a given element are identical in mass and properties
3) Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms
Wednesday, September 9, 2009
Chapter 3, 5 Vocabulary
alkali metals
group
nonmetal
alkaline earth metal
halogen
nucleus
atom
inner transition metal
period
atomic mass
isotope
periodic law
atomic mass unit (amu)
mass number
periodic table
atomic number
metal
proton
cathode ray
metalloid
representative element
Dalton’s atomic theory
neutron
transition metal
electron
noble gas
Chapter 3
absolute zero
hydrometer
qualitative measurement
accepted value
International System of Units (SI)
quantitative measurement
accuracy
Kelvin scale
scientific notation
Celsius scale
kilogram (kg)
significant figures
density
liter (L)
specific gravity
error
meter (m)
temperature
experiment
percent error
volume
gram (g)
precision
weight
Chapter & Section 14-1
inner transition metal
representative element
noble gas
transition metal
Tuesday, September 8, 2009
Extra Credit: Separation of Mixture Quiz
Lab 3: Separation of Mixtures
Bellringer 6
Compounds, Mixtures and Elements
Seperation Techniques
Distillation involves 2 stages and both are physical state changes.
(1) The liquid or solution mixture is boiled to vaporise the most volatile component in the mixture (liquid ==> gas). The ant-bumping granules give a smoother boiling action.
(2) The vapour is cooled by cold water in the condenser to condense (gas ==> liquid) it back to a liquid (the distillate) which is collected.
This can be used to purify water because the dissolved solids have a much higher boiling point and will not evaporate with the steam, BUT it is too simple a method to separate a mixture of liquids especially if the boiling points are relatively close.
Fractional distillation involves 2 main stages and both are physical state changes. It can only work with liquids with different boiling points. However, this method only works if all the liquids in the mixture are miscible (e.g. alcohol/water, crude oil etc.) and do NOT separate out into layers like oil/water.
(1) The liquid or solution mixture is boiled to vaporise the most volatile component in the mixture (liquid ==>gas). The ant-bumping granules give a smoother boiling action.
(2) The vapour passes up through a fractionating column, where the separation takes place (theory at the end). This column is not used in the simple distillation described above.
(3) The vapour is cooled by cold water in the condenser to condense (gas ==> liquid) it back to a liquid (the distillate) which is collected.
This can be used to separate alcohol from a fermented sugar solution.
It is used on a large scale to separate the components of crude oil, because the different hydrocarbons have different boiling and condensation points (see oil).
FRACTIONAL DISTILLATION THEORY:
Imagine green liquid is a mixture of a blue liquid (boiling point 80oC) and a yellow liquid (boiling point 100oC), so we have a coloured diagram simulation of a colourless alcohol and water mixture! As the vapour from the boiling mixture enters the fractionating column it begins to cool and condense. The highest boiling or least volatile liquid tends to condense more i.e. the yellow liquid (water). The lower boiling more volatile blue liquid gets further up the column. Gradually up the column the blue and yellow separate from each other so that yellow condenses back into the flask and pure blue distils over to be collected. The 1st liquid, the lowest boiling point, is called the 1st fraction and each liquid distils over when the top of the column reaches its particular boiling point to give the 2nd, 3rd fraction etc.
To increase the separation efficiency of the tall fractionating column, it is usually packed with glass beads, short glass tubes or glass rings etc. which greatly increase the surface area for evaporation and condensation.
In the distillation of crude oil the different fractions are condensed out at different points in a huge fractionating column. At the top are the very low boiling fuel gases like butane and at the bottom are the high boiling big molecules of waxes and tar.
This method of separation is used to see what coloured materials make up e.g. a food dye analysis.
The material to be separated e.g. a food dye (6) is dissolved in a solvent and carefully spotted onto chromatography paper or a thin layer of a white mineral material on a glass sheet. Alongside it are spotted known colours on a 'start line' (1-5).
The paper is carefully dipped into a solvent, which is absorbed into the paper and rises up it. The solvent may be water or an organic liquid like an alcohol (e.g. ethanol) or a hydrocarbon, so-called non-aqueous solvents. For accurate work the distance moved by the solent is marked on carefully with a pencil and the distances moved by each 'centre' of the coloured spots is also measured. These can be compared with known substances BUT if so, the identical paper and solvent must be used (See Rf values below).
Due to different solubilities and different molecular 'adhesion' some colours move more than others up the paper, so effecting the separation of the different coloured molecules.
Any colour which horizontally matches another is likely to be the same molecule i.e. red (1 and 6), brown (3 and 6) and blue (4 and 6) match, showing these three are all in the food dye (6).
The distance a substance moves, compared to the distance the solvent front moves (top of grey area on 2nd diagram) is called the reference or Rf valueand has a value of 0.0 (not moved - no good), to 1.0 (too soluble - no good either), but Rf ratio values between 0.1 and 0.9 can be useful for analysis and identification.
Rf = distance moved by dissolved substance (solute) / distance moved by solvent.
Some technical terms: The substances (solutes) to be analysed must dissolve in the solvent, which is called the mobile phase because it moves. The paper or thin layer of material on which the separation takes place is called the stationary or immobile phase because it doesn't move.
It is possible to analyse colourless mixture if the components can be made coloured e.g. protein can be broken down into amino acids and coloured purple by a chemical reagent called Ninhydrin and many colourless organic molecules fluoresce when ultra-violet light is shone on them. These are called locating agents.
Thin layer chromatograpy (t.l.c) is where a layer of paste is thinly and evenly spread on e.g. a glass plate. The paste consists of the solid immobile phase like aluminium oxide dispersesd in a liquid such as water. The plate is allowed to dry and then used in the same way as paper chromatography.
Monday, September 7, 2009
Thursday, September 3, 2009
Wednesday, September 2, 2009
Quiz 1-Friday Sept 4 (A) and Tuesday Sept 8 (B)
1. Lab Safety
2. Lab Equipment
3. Scientific Method
4. Metric System
5. Matter
6. Physical and Chemical Changes
Physical and Chemical Properties
Boiling Point
Freezing Point
Ductile
Malleability
Conductivity
Viscosity
Density
Can you describe and differentiate these words?
5 Signs of Chemical Change:
1. Change in color
2. Production of gas
3. Change in mass
4. Form precipitate
5. Produce energy
Tuesday, September 1, 2009
Lab 2
Differentiate between physical and chemical changes.
Make measurements using various types of lab equipment.
Compare density to viscosity.
Procedure
Lab teams will travel to six stations. At each station is a task to be performed by the lab team. Follow the instructions at each station and record your findings. Each team member will assume one of four roles – materials manager, facilitator, timer and recorder during this lab. All safety precautions should be taken to prevent any exposures to hazards.
Station 1 Density
Using the scale provided, weigh each bar of soap (mass). Using its dimensions (l x b x h), calculate its volume. Determine the density of each bar of soap. (D=m/v)
Question
What is different about the two bars of soap? Which bar of soap is a better value?
Station 2 Viscosity
Rank the substances by viscosity.
__ oil
__ water
__ honey
___ hair gel
Explain your choices.
Station 3
Crush the sample tablet. Place the pieces in the film canister. Add a little bit of water and quickly close the canister and turn it upside down. Step back from the canister and observe the reaction. Make sure you do not point the canister at any person. Goggles are needed during this experiment.
Question
Is this a chemical or physical change?
Station 4
Grab a handle of detergent. Do not let go. Dip your entire hand in the water bucket. Note the feeling in your hand and record your observations.
Question
What did you feel in your hand? Is this a chemical or physical change?
Station 5
Light a candle. Notice what is happening to the wax and record your observations.
Question
Is this a chemical or physical change?
Station 6
Place a small amount of sugar in the dish. Drop several drops of sulfuric acid to the sugar. Note the reaction and record your observations.
Question
Is this is chemical or physical change?