There are 3 types of chemical bonds
Ionic bonds: the transfer between 2 atoms to form a positive and negative ion.
Non-polar covalent bonds: equal sharing of electrons
Polar covalent bonding: unequal sharing of electrons
Ionic bonding uses an electrostatic force. That is the force that exists between particles that are charged as a result of attraction or replusion. (remember, opposites attract? Opposite charges attract and like charges repel). These bonds are very strong and have a high melting temperature.
So, I know you guys have a burning question:
Why do things lose valence electrons? This is explained by electronegativity. Metals have low electronegativity and non-metals have high electronegativity, as we learned in the last chapter. The electronegativity decreases to the right across the periodic table. The difference in the electronegativity will determine the electron sharing and determine if it is equally shared or unequally shared.
Here is how to figure that out! This is the formula:
ENeg Diff.= [ENeg1 - ENeg 2]
If it is a non polar covalent bond, the difference will be <0.5
If it is a polar covalent bond, the difference will be >0.5 and <1.8
If it is an ionic bond, the difference is >1.8
If ENeg Diff <0.5 it's a non polar covalent bond
If ENeg Diff > 0.5 and <1.8 it's a polar covalent bond
If ENeg Diff > 1.8 it's an ionic bond
Lets try an example:
Arsenic and Sulfur
Arsenic is 2.18 and Sulfur is 2.58. |2.18-2.58| = 0.40, therefore it is covalent.
Cobalt and Bromine
Cobalt is 1.88 and Bromine is 2.96 |1.88-2.96| = 1.08, therefore it is a polar covalent bond./
To draw diagrams of the compounds, draw the central atom in the middle and distribute the remaining atoms around it. Draw arrows indicating the direction of the polarity. Draw the partial positive and partial negative charges.
Partial Positive sign is the almost 8 but cut-off sign with a +
Partial Negative sign is the same thing but with a -
What is polarity?
Different Kinds of Bonds
Showing posts with label Ilanna. Show all posts
Showing posts with label Ilanna. Show all posts
Thursday, June 2, 2011
Tuesday, May 17, 2011
More of the Periodic Table!
The 1800s was huge for discoveries regarding the periodic table. Here's what you need to know:
Law of Octaves - John Newland
He proposed that elements are arranged according to their atomic weight
Mendeleev:
Discovered that certain features of elements recurred when elements were arranged in order according to mass. Therefore, he decided to organize the elements in periods and families or groups, also known in the general English language as a row or a column. He even left gaps in the table, leaving room for other elements with similar characteristics to be discovered. (Smart cookie!) He is known as the 'father' of the periodic table.
The smart cookie! (Mendeleev)
Modern Times:
Periodic Law : Elements recur periodically when arranged from lowest to highest atomic number.
-Elements are arranged according to their atomic number. (Got that wrong on the test, damn! But at least you'll know now!)
Here are some fun videos for you!
The Mendeleev Song!
History on Mendeleev
Newland documentary
Now your daily chemistry related lolcat!
Enjoy and I hope everyone did great on the test!
Law of Octaves - John Newland
He proposed that elements are arranged according to their atomic weight
Mendeleev:
Discovered that certain features of elements recurred when elements were arranged in order according to mass. Therefore, he decided to organize the elements in periods and families or groups, also known in the general English language as a row or a column. He even left gaps in the table, leaving room for other elements with similar characteristics to be discovered. (Smart cookie!) He is known as the 'father' of the periodic table.
Modern Times:
Periodic Law : Elements recur periodically when arranged from lowest to highest atomic number.
-Elements are arranged according to their atomic number. (Got that wrong on the test, damn! But at least you'll know now!)
Here are some fun videos for you!
The Mendeleev Song!
History on Mendeleev
Newland documentary
Now your daily chemistry related lolcat!
Enjoy and I hope everyone did great on the test!
Electron Configuration
For me, electron configurations started out very confusing, but now that I understand, I'll try and show you what works best for me.
First thing to do is to memorize this chart. We aren't given it during quizzes/tests so it is important to know the order.
You also need to know this:
S-types have one orbital (2 electrons or spaces)
P-types have 3 orbitals (6 electrons or spaces)
D-types have 5 orbitals (10 electrons or spaces)
F-types have 7 orbitals (14 electrons or spaces)
Now if I were you, I would be saying spaces? I'm confused!
But here is how it helps!
_ _ _ _ _ _ _ _ _
1s 2s 2p 3s 3p
Now, let's start with something easy like a Helium atom. If it is an atom, it has the same number of protons and electrons. Helium's atomic number is 2 therefore it has two protons/electrons. Because it has 2 electrons, fill in one upwards arrow and one downwards arrow. That shell is now full.
Not only is that shell full, we have used up all the electrons!
Therefore the electronic configuration for Helium is 1s2.
Lets use a more complicated one now and test that knowledge!
Lets try a sodium atom. This atom has 11 protons/electrons. Keep going until all those electrons are full.
I would draw it but since its on the computer I can't. So we'll use an astrix to show it.
** ** ** ** ** *
_ _ _ _ _ _ _ _ _
1s 2s 2p 3s 3p
As you can see we have used all 11 electrons. So let's write it!
In written form it would be 1s2 2s2 2p6 3s1
As you can see the exponents add up to the number of electrons.
If you are still completely confused what I mean when I say arrows, here is a visual example of what I am talking about.
Orbital diagram for Sodium
Now lets try one with ions!
Electron configuration for N3-
Because it has a charge of -3, there are three extra electrons to deal with. Normally, nitrogen has 7 electrons. But because of its charge, we have to add 3 more.
If it has 10 electrons, write it out until you run out of electrons.
1s2 2s2 2p6
As you can see the exponents add up to 10, the number of electrons for the N3- ion!
The nitride ion, N3ˉ, has an electron arrangement of 1s2, 2s2, 2p6
Without the 3- charge, N would look like this: 1s2 2s2 2p3. The extra 3 electrons fill the 2p orbital and stabilizes the ion, making it similar to a noble gas, which all elements want to be like. (But you will learn more about that later)
What else you need to know:
Ground State: electrons are in their lowest possible level
Excited State: Electrons are in energy levels other than the one that is lowest available.
If the electrons in the excited state, you should try for extra practice to put them in their ground state.
Thanks for reading, of course I will include a lolcat to thank you for following along!
First thing to do is to memorize this chart. We aren't given it during quizzes/tests so it is important to know the order.
You also need to know this:
S-types have one orbital (2 electrons or spaces)
P-types have 3 orbitals (6 electrons or spaces)
D-types have 5 orbitals (10 electrons or spaces)
F-types have 7 orbitals (14 electrons or spaces)
Now if I were you, I would be saying spaces? I'm confused!
But here is how it helps!
_ _ _ _ _ _ _ _ _
1s 2s 2p 3s 3p
Now, let's start with something easy like a Helium atom. If it is an atom, it has the same number of protons and electrons. Helium's atomic number is 2 therefore it has two protons/electrons. Because it has 2 electrons, fill in one upwards arrow and one downwards arrow. That shell is now full.
Not only is that shell full, we have used up all the electrons!
Therefore the electronic configuration for Helium is 1s2.
Lets use a more complicated one now and test that knowledge!
Lets try a sodium atom. This atom has 11 protons/electrons. Keep going until all those electrons are full.
I would draw it but since its on the computer I can't. So we'll use an astrix to show it.
** ** ** ** ** *
_ _ _ _ _ _ _ _ _
1s 2s 2p 3s 3p
As you can see we have used all 11 electrons. So let's write it!
In written form it would be 1s2 2s2 2p6 3s1
As you can see the exponents add up to the number of electrons.
If you are still completely confused what I mean when I say arrows, here is a visual example of what I am talking about.
Orbital diagram for Sodium
Now lets try one with ions!
Electron configuration for N3-
Because it has a charge of -3, there are three extra electrons to deal with. Normally, nitrogen has 7 electrons. But because of its charge, we have to add 3 more.
If it has 10 electrons, write it out until you run out of electrons.
1s2 2s2 2p6
As you can see the exponents add up to 10, the number of electrons for the N3- ion!
The nitride ion, N3ˉ, has an electron arrangement of 1s2, 2s2, 2p6
Without the 3- charge, N would look like this: 1s2 2s2 2p3. The extra 3 electrons fill the 2p orbital and stabilizes the ion, making it similar to a noble gas, which all elements want to be like. (But you will learn more about that later)
What else you need to know:
Ground State: electrons are in their lowest possible level
Excited State: Electrons are in energy levels other than the one that is lowest available.
If the electrons in the excited state, you should try for extra practice to put them in their ground state.
Thanks for reading, of course I will include a lolcat to thank you for following along!
Saturday, May 14, 2011
Periodic Table Trends
This class we did an activity to discover the trends in the periodic table.
We found out the trends by graphing and finding out what we noticed was a trend.
Here is what we found:
Density: the degree of compactness of a substance. As the atomic number increases, so does the density.
Melting Point: The temperature at which a given solid will melt.
Boiling Point: The temperature at which a liquid boils and turns to vapor
Melting points decrease as you move down a group, and increase as you move across a period.
Ionization Energy: The energy required to remove the outermost electron in the atom. It increases as you move across a period, and decreases as you move down a group.
Electronegativity: The tendency of an atom to attract electrons in the formation of anionic bonds. Elements become less electronegative as you move down a group, and more electronegative when you move across a period.
Atomic Radius: Measure of the size of its atoms, usually the mean or typical distance from the nucleus to the boundary of the surrounding electrons. This decreases as you move across a period, and increases as you move down a group.
Next class we focused on elaborating on these trends so stay tuned!
We found out the trends by graphing and finding out what we noticed was a trend.
Here is what we found:
Density: the degree of compactness of a substance. As the atomic number increases, so does the density.
Melting Point: The temperature at which a given solid will melt.
Boiling Point: The temperature at which a liquid boils and turns to vapor
Melting points decrease as you move down a group, and increase as you move across a period.
Ionization Energy: The energy required to remove the outermost electron in the atom. It increases as you move across a period, and decreases as you move down a group.
Electronegativity: The tendency of an atom to attract electrons in the formation of anionic bonds. Elements become less electronegative as you move down a group, and more electronegative when you move across a period.
Atomic Radius: Measure of the size of its atoms, usually the mean or typical distance from the nucleus to the boundary of the surrounding electrons. This decreases as you move across a period, and increases as you move down a group.
Next class we focused on elaborating on these trends so stay tuned!
Also, Ms. Chen showed us this great website http://www.ptable.com/ where you can play around with the trends and find out some new trends! I know I will be using it to study!
Monday, February 7, 2011
Lab 5B: Types of Chemical Reactions
In class we completed Lab 5B dealing with chemical reactions.
I had completed the lab once before in Grade 10, but regardless, it's always good to do things a second time! You catch things you missed the first time.
The first thing you always need to do is wear your safety goggles. Mrs Chen caught me a few times without them and she is right, always safety first!
During this lab, you get 7 test tubes and complete a reaction in each one. We later determined the chemical equations for the reactions.
Reaction 1: For reaction 1, you adjust a burner flame to high heat, and then using crucible tongs (safety first), you hold a 6 cm length of bare copper wire in the hottest part of the flame for a few minutes.
During this experiment, we were asked to take observations before, during, and after.
In Reaction 1, before attempting anything, we observed that the wire was stiff and copper coloured. During the experiment, part of the wire exposed to the bunsen burner began to glow, there was a slight kink, and it began to turn black. After the experiment, it was black.
We determined the chemical equation for this reaction was 2Cu + O2 --> 2CuO, and classified it as a synthesis reaction.
Reaction 2: In reaction 2, you clean an iron nail with a piece of steel wool so that the surface of the nail is shiny. The nail is then placed in a test tube and copper (II) sulfate is added so half of the nail is covered.
Before, we noticed that the iron nail was brown, and the solution was an intense blue. During, bubbles and a thick layer formed. After, a copper coloured outer coating grew, it was relatively thick and darker in colour.
We determined the chemical equation for this reaction was 1Fe + 1CuSO4 --> 1Cu + FeSO4 and classified it is a single replacement reaction.
Reaction 3: In reaction 3, solid copper (II) sulfate pentahydrate was put in a test tube so that it was 1/3 full. Then, using the test tube clamp, we held the test tube and its contests at an angle away, heated the test tube, and moved it back and forth over a burner flame. We continued heating until no change was observed. Before, the solution appeared to be powdery and sandlike. During, it turned white, steamed, and bubbled. After, it turned completely white on the outside, bubbled, with lots of steam and sizzling sounds.
We determined the chemical equation for this reaction was 1CuSO4 x 5H20 --> 1CuSO4 + 1H2O and classified it as a double replacement reaction.
Reaction 4: In reaction 4, we allowed the test tube and contests from Reaction 3 to cool. We then used a medicine dropper to add 2 or 3 drops of water to the test tube. Before, the appearance was dirty white with blue specks, and dry and hard. During, it became wet. After, the water was absorbing and the appearance was a light colour.
We determined the chemical equation for this reaction was 1CuSO4 + 5H2O --> 1CuSO4 x 5H20 and classified it as a double replacement reaction.
Reaction 5: For this reaction, we filled a test tube 1/4 full with calcium chloride solution. Then we filled a second test tube full with sodium carbonate solution. We then poured the calcium chloride solution into the test tube containing sodium carbonate solution. Before, the solution appeared to be clear. During the reaction it foamed, became a cloudy white, and after it was thicker, gooey and a dirty white colour.
We determined the chemical equation for this reaction was 1CaCl2 + 1Na2CO3 --> 2NaCl + 1CaCO3 and classified it as a double replacement reaction.
Reaction 6: With this reaction, we placed a piece of mossy zinc in a test tube. Then added hydrochloric acid solution to the test tube until the mossy zinc was completely covered. Before, it appeared to be exactly what it was called - mossy zinc. During, it expanded, bubbled, and turned a grey sandy colour. After, it slightly hardened and condensed, and became a solid.
We determined the chemical equation for this reaction was 1Zn + 2HCl --> 1H2 + 1ZnCl2 and classified it as single replacement.
Reaction 7: For this reaction, a test tube was half filled with hydrogen peroxide solution. Then, a small amount of manganese (IV) oxide was added. We tested the gas by placing a glowing splint into the mouth of the test tube. Before, we observed that the liquid was clear. During the experiment, it foamed up and seperated. After, it bubbled from the middle, steamed with the glowing splint, turned grey at the top (light) and the top resembled a candle wick.
All in all, it was a pretty cool lab! Here are some videos, some that were shown to us by Ms Mak last year, and some I personally recommend!
This is my favourite!
Several reactions, including single and double replacement!
Animations on reactions!
Who doesn't love a little Bill Nye?
Thats it for now! Have a great long weekend!
Ilanna
I had completed the lab once before in Grade 10, but regardless, it's always good to do things a second time! You catch things you missed the first time.
The first thing you always need to do is wear your safety goggles. Mrs Chen caught me a few times without them and she is right, always safety first!
During this lab, you get 7 test tubes and complete a reaction in each one. We later determined the chemical equations for the reactions.
Reaction 1: For reaction 1, you adjust a burner flame to high heat, and then using crucible tongs (safety first), you hold a 6 cm length of bare copper wire in the hottest part of the flame for a few minutes.
During this experiment, we were asked to take observations before, during, and after.
In Reaction 1, before attempting anything, we observed that the wire was stiff and copper coloured. During the experiment, part of the wire exposed to the bunsen burner began to glow, there was a slight kink, and it began to turn black. After the experiment, it was black.
We determined the chemical equation for this reaction was 2Cu + O2 --> 2CuO, and classified it as a synthesis reaction.
Reaction 2: In reaction 2, you clean an iron nail with a piece of steel wool so that the surface of the nail is shiny. The nail is then placed in a test tube and copper (II) sulfate is added so half of the nail is covered.
Before, we noticed that the iron nail was brown, and the solution was an intense blue. During, bubbles and a thick layer formed. After, a copper coloured outer coating grew, it was relatively thick and darker in colour.
We determined the chemical equation for this reaction was 1Fe + 1CuSO4 --> 1Cu + FeSO4 and classified it is a single replacement reaction.
Reaction 3: In reaction 3, solid copper (II) sulfate pentahydrate was put in a test tube so that it was 1/3 full. Then, using the test tube clamp, we held the test tube and its contests at an angle away, heated the test tube, and moved it back and forth over a burner flame. We continued heating until no change was observed. Before, the solution appeared to be powdery and sandlike. During, it turned white, steamed, and bubbled. After, it turned completely white on the outside, bubbled, with lots of steam and sizzling sounds.
We determined the chemical equation for this reaction was 1CuSO4 x 5H20 --> 1CuSO4 + 1H2O and classified it as a double replacement reaction.
Reaction 4: In reaction 4, we allowed the test tube and contests from Reaction 3 to cool. We then used a medicine dropper to add 2 or 3 drops of water to the test tube. Before, the appearance was dirty white with blue specks, and dry and hard. During, it became wet. After, the water was absorbing and the appearance was a light colour.
We determined the chemical equation for this reaction was 1CuSO4 + 5H2O --> 1CuSO4 x 5H20 and classified it as a double replacement reaction.
Reaction 5: For this reaction, we filled a test tube 1/4 full with calcium chloride solution. Then we filled a second test tube full with sodium carbonate solution. We then poured the calcium chloride solution into the test tube containing sodium carbonate solution. Before, the solution appeared to be clear. During the reaction it foamed, became a cloudy white, and after it was thicker, gooey and a dirty white colour.
We determined the chemical equation for this reaction was 1CaCl2 + 1Na2CO3 --> 2NaCl + 1CaCO3 and classified it as a double replacement reaction.
Reaction 6: With this reaction, we placed a piece of mossy zinc in a test tube. Then added hydrochloric acid solution to the test tube until the mossy zinc was completely covered. Before, it appeared to be exactly what it was called - mossy zinc. During, it expanded, bubbled, and turned a grey sandy colour. After, it slightly hardened and condensed, and became a solid.
We determined the chemical equation for this reaction was 1Zn + 2HCl --> 1H2 + 1ZnCl2 and classified it as single replacement.
Reaction 7: For this reaction, a test tube was half filled with hydrogen peroxide solution. Then, a small amount of manganese (IV) oxide was added. We tested the gas by placing a glowing splint into the mouth of the test tube. Before, we observed that the liquid was clear. During the experiment, it foamed up and seperated. After, it bubbled from the middle, steamed with the glowing splint, turned grey at the top (light) and the top resembled a candle wick.
All in all, it was a pretty cool lab! Here are some videos, some that were shown to us by Ms Mak last year, and some I personally recommend!
This is my favourite!
Several reactions, including single and double replacement!
Animations on reactions!
Who doesn't love a little Bill Nye?
Thats it for now! Have a great long weekend!
Ilanna
Saturday, October 2, 2010
Textbook Summary
Summarizing for a part of the reading (25-34) from the textbook:
What are chemists?
Chemists specialize in matter:
A mixture is two or more kinds of matter that have separate identities. It is easily separated into component parts, and some people say it is impure.
Mixtures that CAN be separated:
Check out this video called the Atom Song!
Skip to 30 seconds to get to the song.
The Atom Song!
Summarizing for you a part of the reading (36-39) from the textbook:
The general idea here is that matter is made of atoms.
The idea that matter is made of atoms did not become popular until the early 1800s.
Now, lets look at some terms:
Atom: The smallest possible piece of something, they vary in size and mass
Elements: Pure substances that cannot be broken down
Solid: Holds its shape since atoms are stuck together
Liquid: The temperature is increased and atoms will vibrate and flow past one another
Molecule: particles made up of more than one atom
Compounds: Made by combining elements in definite proportions (made of 2 or more types of atoms)
Ions: particles that have an electrical charge
Ionic: melt to form ions
Molecular: melt as molecules
My Socials Teacher once told me that once you know the meaning of the terms, it makes the material much easier to learn. So hopefully this helps!
Here's a cool video about atoms and molecules, and the guy talking has braces! It's pretty funny.
Click here
What are chemists?
Chemists specialize in matter:
- what it is
- how one kind differs form another
- what different kinds have in common
- how one kind can be changed to another
- how it can be kept the same
Water is one of the most familiar kinds of matter. The temperature at which matter changes from a liquid to a gas is called boiling point.
A mixture is two or more kinds of matter that have separate identities. It is easily separated into component parts, and some people say it is impure.
Mixtures can be heterogeneous mixtures or homogeneous mixtures.
Heterogeneous mixtures- the substances in the kind of a mixture are not spread out evenly.
Example: Salad Dressing
Homogeneous mixtures- the substances are spread evenly throughout, a homogeneous mixture is called a solution.
Example: Vinegar
By adding things to pure water, you can quickly find that there are no mixtures that do not scatter light.
If table salt is added, it disappears. You can taste it, but it cannot be seen.
Therefore, the table salt does not scatter light.
Therefore, the table salt does not scatter light.
Solutions - mixtures that look uniform throughout and do not scatter light.
Distillation - separates most mixtures.
Mixtures that CAN be separated:
- household ammonia
- alcoholic beverages - for example, whiskey
Pure Substances have a constant boiling point. Mixtures ordinarily do not.
Freezing Point - the temperature at which a liquid changes to a solid
Melting Point - the temperature at which a solid changes to a liquid
Density - a property of matter that describes its mass per unit volume
Chemical Changes - changes that produce a new kind of matter with different properties
Physical Changes - changes that change the appearance, but do not produce new kinds of matter
Decomposition - when one kind of matter comes apart (decomposes) to form two or more kinds of matter
Electrolysis - involves passing an electric current through a substance, causing it to decompose into new kinds of matter
The Law of Definite Composition: A compound always contains two or more elements combined in a definite proportion by mass
The Law of Multiple Proportions: The fact that two or more compounds with different proportions of the same elements can be made.
Check out this video called the Atom Song!
Skip to 30 seconds to get to the song.
The Atom Song!
Summarizing for you a part of the reading (36-39) from the textbook:
The general idea here is that matter is made of atoms.
The idea that matter is made of atoms did not become popular until the early 1800s.
Now, lets look at some terms:
Atom: The smallest possible piece of something, they vary in size and mass
Elements: Pure substances that cannot be broken down
Solid: Holds its shape since atoms are stuck together
Liquid: The temperature is increased and atoms will vibrate and flow past one another
Molecule: particles made up of more than one atom
Compounds: Made by combining elements in definite proportions (made of 2 or more types of atoms)
Ions: particles that have an electrical charge
Ionic: melt to form ions
Molecular: melt as molecules
A very large water molecule
A caffeine molecule
LSD (acid) molecule. Don't try this at home kids!
My Socials Teacher once told me that once you know the meaning of the terms, it makes the material much easier to learn. So hopefully this helps!
Here's a cool video about atoms and molecules, and the guy talking has braces! It's pretty funny.
Click here
Thursday, September 23, 2010
Thursday, September 23rd, 2010
It's the long weekend this weekend! So today, the Happy Halogens worked on getting ready for our quiz on unit conversions for Monday. Here are some helpful resources so that you can feel confident and prepared to get that A+!
Using Julia's instructions, here are some extra practice questions to work on:
Questions
Answers
Also, if you want to try something just for fun, use this to convert anything you want to anything you want!
If you are still lost and confused and don't understand what is going on or how to do it (I know the feeling) this video will help clear up any problems:
The Greatest Unit Conversion Video Ever Made!
Enjoy!
Using Julia's instructions, here are some extra practice questions to work on:
Questions
Answers
Also, if you want to try something just for fun, use this to convert anything you want to anything you want!
If you are still lost and confused and don't understand what is going on or how to do it (I know the feeling) this video will help clear up any problems:
The Greatest Unit Conversion Video Ever Made!
Enjoy!
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