Electron Dot and Lewis Diagrams

So electron dot and lewis diagrams are just one way of modelling an atom/element. However, in these diagrams, it only requires the valence electrons. Today we are going to learn how to draw them and it's actually very simple. *Sorry if the pictures don't show up!! Don't know why it keeps doing that...*

Before we start though, here's some general information you should know about the diagrams:
- The atomic symbol represents the nucleus. Therefore you should write it in the middle.
- You must know the amount of valence electrons to draw the diagram
- Dots around the symbol represent the electrons
- There are four orbitals (one on each side of the nucleus) and each one can hold a maximum of 2 electrons
- Each orbital must have 1 electron before they start pairing up
- All valence electrons must be used
- Each element must have a full valence shell (8 electrons) except for H (2 electrons)

Ok now let's start making diagrams!
Ex. CH4
Step 1: Find the central atom. It's the one furthest from a full shell.
C=4 and H=1 but since H only needs 2 and C needs 8 then C is furthest away from a full shell therefore it is the central atom.

Step 2: Put C in the center to represent the nucleus then draw the dots around it to represent the valence electrons. Once you've done that, draw the H's around the C to make sure that they all have a full shell.

 And VOILA! YOU'RE DONE :D

If you want to do a structural diagram, just replace 2 electrons with lines. So it would look something like this..

Well that covers the basics of it. Here's a video about more complex dot diagrams such as ionic and covalent compounds. 

http://www.youtube.com/watch?v=QKoA3fZ29B0&NR=1

FUNctional GROUPS! how FUN. (:

what is a FUNctional group??
well....
here;s the definition.
Functional groups: is a specific group of atoms in a molecule and gives the molecule the ability to respond in a specific manner.

hmm?
(:

they are :

• organic compounds that have carbon and hydrogen.
• can be a single or a group
• the most popular ones are:

floro (F), Chloro (Cl), Bromo (Br), Iodo ( I)

and finally nitro (NO2)


Properties of Halogens:

• insoluble in water
• unreactive hydrocarbon such as the Teflon
• anything with Cl or Br are more reactive than others
• anything with I on the other hand is even MORE reactive

Properties of Nitro:

• insoluble in water 
• unreactive to chemical attack
• explosive
• have a nice smell or odor

ALCHOLS

• are organic compounds that contains OH

• they can be name by finding the longest chain and replacing the e.
• soluble in water
• poisonous

Note: alcohol chain has the lowest possible chain   

********NEED TO KNOW*********

ALDEHYDE:

- organic compound THAT HAS C=O group at the end of the hydrocarbon chain
- it follows the standard rules
-changes the parent chain ending to "al"
-soluble in water and reactive

MULTIPLE-OH

- a compound has MORE THAN one -OH group number 
-add a -diol, -triol etc ... in the ending 

Ketones

-organic compound that has C=O group at end of the hydrocarbon chain
- it follows the standard rules  and add "one" at the ending to the parent chain

• soluble in water but unreactive

 

VIDEO TIME!!!!!!!!!!

 

did you guys have fun watching those videos?
oh just say yes.
"yes"<- anonymous person.
"yay!!" <- me

yes. im crazy.
O.O


bye everyone!!
have FUN studying!

Alkenes and Alkynes

Alkenes 
to start off, let's look at a visual!

( here's chemical structure of an ethylene)

                                                                                   A.K.A. ( also know as)

 moving on..

• hydrocarbons with double bonds make up this family ( alkene )
• it's unsaturated
• they are also insoluble and flammable
• and the ending changes from ane to ene 

**The formula for alkenes is C_nH_2n**

Rules for naming


Step 1: fine the longest chain
Step 2:  find the # of carbon to get the lowest # for the start of the double bond; then place that number   before the name 
Step 3: name and number all the side groups and arrange them alphabethically.

FOR EXAMPLE: 

CH3CH=CHCH3

- so, the longest chain is.. four. so that's butane 

- now remember to change the ending into ene

- now the bond is located at the second place

- so you call this.. 2-butane.

(pretty easy ryt?)

how about this one?

give it a try.  

     CH3     CH3
      |       |
CH3CH2CHCH2CH=CCH3

 since the double bond is at the end. you count starting from RIGHT to LEFT.

answer: 

2,5-dimethyl-2-heptene

 Alkanes with two double bonds are called dienes, those with three are called trienes, and so on...

Now, when it comes to alkenes, some molecules will have the same structure but they have different geometry.

 "Cis" and "Trans"

geometric isomerism among alkenes.

• this is used so we can differentiate 2 chemical formulas that are the same but are arranged differently.
• "cis" and "trans" are the two geometric isomers
• "cis" means on the same side
• "trans" means on the opposite ends

FOR EXAMPLE:

cis-2-butene

CH3     CH3  ( see how CH3 are on the same sides ?)
 \     /
  C = C
 /     \
H       H

trans-2-butene

CH3     H   ( see how CH3 are on the opposite sides?)
 \     /
  C = C
 /     \
H       CH3

here;s a better visual picture (:

LEFT PICTURE: cis-2-butene

RIGHT PICTURE: trans-2-butene 

**Note: that if the top and bottom are the same; there's no need to use cis or trans.**

Alkynes 

• now alkynes have the same rules as alkenes except they ends with yne 

  • compounds with low polarity

    • have one or triple bond

      • formula is  CnH2n-2

        for example:

        

  Here's a diagram for more examples of different types of alkyne and alkene's molecular formulas.

  

   still dont get it?

  here's some videos you can watch.

   
  
  
  
  

sry fellow bloggers but i have no joke for today. 

i dont feel like being funny today.

so good day to u all!

or should i say goodnyt!

ta-ta

O.O 

Organic Chemistry Part 1

Organic chemistry is defined as the chemistry of CARBON compounds.  
Carbon can produce millions of molecules is related to its electron structure.  Each carbon has four electrons available for bonding which can be shared in four covalent bonds with other atoms.
They can lin with other atoms in single bonds/double/triple bonds

Alkanes 

• are a hydrocarbon in single bonds
• non polar molecules
•  saturated: not possible for another atom to bond to the structure
• end in ane
• formula: CnH2n+2

• can have side branched called substituted hydrocarbons
• alkyl group: an alkane which has lost 1 hydrogen can be attached to them

• alkyl goup cannot esist by themselves, they must be attached to a larger hydrocarbon

• the longest chain of carbon determines the parent name of the hydrocarbon

• carbons in the parent are numbered consecutively so that groups are indicated by the lowest numbers

• the position of each attached group is indicated by a number

• if there aremorethan 1 type of alkyl goup, list them alphabetically,  put its position number in fount, put a dash between each alkayl

a nice online teacher....

nice video to watch

Chemical bonding

1. The electrostatic forces between charged particles    
first of all.... you have to know this two terms.

bond energy - the energy involved in the processes of bond forming and bond breaking, a measure of bond strength
electrostatic force - a force existing as a result of the attraction or repulsion between two charged particles.

• opposite charges attract each other  (eg. proton and proton)

• same charges repel each other (eg. proton and electron)

when attractive force is greater than repulsive force, a chemical bond is formed.  This is a situation in which a pair of electrons is simultaneously attracted to two atomic nuclei.  two oppositely charged particles approach each other, the potential energy decrease.   For many atoms, the formation of a chemical bond with another atoms leads to a decrease in the energy of the system.

When an atom is involved in a chemical bond, some of the atoms' orbitals are modified to allow electrons to be shared between two adjacent atoms. However,  atoms share electrons but not necessarily equally....this leads to the next topic

2. types of chemical bonding
In science 10, we learned that chemical bond can be either ionic or covalent and now in chem 11, covalent bonding can be divided into two new categories:  polar or non polar. This classification is based on whether the electrons are shared equally.
Here are the three types of bonding:

1. ionic bond - the electrons are transferred from metal to non metal.  
2. non polar bond- the electrons are shared equally
3. polar bond - the electrons are not shared equally

To find out which type of bond is formed, you have to know their electronegativity.
Electronegativity of an atom is the tendency of the atom to attract electrons from a neighbouring atom.
In general, values increase from left to right and decrease down a group
Most is flourine and least is celsium

when the difference of two atoms is:
less than 5... a covalent bond is formed
between 0.5 and 1.8....a polar covalent bond is formed
greater than 1.8... an ionic bond is formed

3.a closer look to polar covalent compounds
Polar covalent bonding
the atom with the great electronegativity will pull the electrons in the onds, move time will spend on this electron
the atoms:
with higher electronegativity will form a partial negative charge
with lower electronegativity will form a partial positive charge

here is a more detailed video about polar covalent compounds

Bohr Models

So, who is Bohr and why is he important you ask?
Well, its this guy right here..

Anyways, he contributed a lot to chemistry and our understanding of atoms. One of them is creating the Bohr model, which is a diagram of the atom showing that electrons orbit around the nucleus in the center. 

When electrons absorb energy, they are capable of jumping up to a higher orbital/shell.

But when electrons move from a higher shell to a lower one, they release energy as a photon of light, which is then emitted from the atom. 

The strength of the energy causes an atom to have different colours from each other or in other words, they create their own spectra of light.

Now it's time to learn how to draw your very own Bohr model, yay!

1. Figure out how many protons and neutrons there are in the element. As an example we'll use Sodium. To find out how many protons there are, look at your periodic table and find Sodium. Then look at the atomic number and you've found the protons! Now for the neutrons, you just have to subtract the amount of protons from the atomic mass and voila! (Round up to the nearest whole number)

2. Now that you've found the number of neutrons and protons, write it in the middle to represent the nucleus. Instead of writing the full word out though, just write "p" as proton and "n" as neutron.

3. Then you find the number of electrons. In this case it's 11. Now that we know that, we can draw the orbitals around the nucleus. Each shell has a maximum amount of electrons it can hold. The first one (closest to the nucleus) can hold a maximum of 2. The second a maximum of 8. The third one can hold a maximum of 8-18 and so on. Also, when drawing the electrons, they should form 4 groups of 2 around the nucleus. So it should look a little something like this: 

Thanks for reading. I hope you understand everything >.> and if you don't, then for further (probably better) explanation, watch this video :)

http://www.youtube.com/watch?v=iih6rJ2S6pk