In previous classes, we went over alkanes, alkenes, and alkynes. Now we are going to go over the chains that contain not only carbon and hydrogen but many other elements.
Halides and Nitro Compunds: When halogens are added into the compund, the names of these elements will be placed infront of the parent chain when naming. The halogens used are F-Fluoro, Cl-chloro, Br-bromo, and I-iodo. And nitro is also used too. The names will end with -ane.
Alcohols: You can tell when the compund is an Alcohol when there is a branched OH somewhere in the middle of the compound. The ending of the name is -ol .When there are two or more OHs add diol, or triol to the ending.
Aldehydes: Double bonded oxygen at the end of the chain. The name ends with -al.
Ketones: Double bonded ocygen in the MIDDLE of the chain (not on either end). Ends with -one when naming.
Monday, June 6, 2011
Chemical Bonding
In Chemical Bonding, there are three types of bonding. There are covalent bond, polar covalent bonds, and ionic bonds.
* Electronegativity- the attraction of an atom for for a shared pair of electrons.
Firstly is the covalent bond. A covalent bond is when two atoms are sharing a pair of electrons relatively evenly. When the electronegativity between two atoms are 0.5 or less, it is a covalent bond.
http://scienceelearning.wordpress.com/page/7/
Example: F and F
|3.98-3.98=0|
Since the electronegativity difference is 0, it is a covalent bond.
Next is the polar covalent bond. A polar covalent bond occurs when there is an unequal attraction for shared electorns. One atom will end up with a slightly negative charge and the other will end up with a slightly positive charge. For polar covalent bonds, the attraction is stronger so it is harder to seperate the atoms.
Example: B and Cl
|3.16-2.04=1.12|
Since the electronegativity difference is over 0.5 and under 1.8, it is a polar covalent bond.
Lastly is the ionic bond. Unlike the covalent and the polar covalent bond, the ionic bond does not share the electrons. An ionic bond is made by the attraction of two oppositely charged ions.When the electronegativity difference is 1.8 or more, it is considered a ionic bond.
Example: K and Br
|2.96-.0.82=2.14|
Since the electronegativity difference is over 1.8, it is an ionic bond.
* Electronegativity- the attraction of an atom for for a shared pair of electrons.
Firstly is the covalent bond. A covalent bond is when two atoms are sharing a pair of electrons relatively evenly. When the electronegativity between two atoms are 0.5 or less, it is a covalent bond.
http://scienceelearning.wordpress.com/page/7/
Example: F and F
|3.98-3.98=0|
Since the electronegativity difference is 0, it is a covalent bond.
Next is the polar covalent bond. A polar covalent bond occurs when there is an unequal attraction for shared electorns. One atom will end up with a slightly negative charge and the other will end up with a slightly positive charge. For polar covalent bonds, the attraction is stronger so it is harder to seperate the atoms.
Example: B and Cl
|3.16-2.04=1.12|
Since the electronegativity difference is over 0.5 and under 1.8, it is a polar covalent bond.
Lastly is the ionic bond. Unlike the covalent and the polar covalent bond, the ionic bond does not share the electrons. An ionic bond is made by the attraction of two oppositely charged ions.When the electronegativity difference is 1.8 or more, it is considered a ionic bond.
Example: K and Br
|2.96-.0.82=2.14|
Since the electronegativity difference is over 1.8, it is an ionic bond.
-Victoria
Saturday, June 4, 2011
Organic Chemistry
Alkanes (Straight chain with no branches)
- Hydrocarbon ---> A compound containing only hydrogen and carbon
- They are saturated because each Carbon atom is bonded to the maximum possible number of other atoms
- Carbon atoms are bonded by single bonds
- the names of hydrocarbons end in '-ane'
Name of parent compound chain
- The name is of the hydrocarbon is determined by the number of carbon it has
- the name of the alkyl group
- finally, the name of the parent hydrocarbon chain, to which the alkyl group is attached
CH3 This is called 2-methylpentane
- Hydrocarbon ---> A compound containing only hydrogen and carbon
- They are saturated because each Carbon atom is bonded to the maximum possible number of other atoms
- Carbon atoms are bonded by single bonds
- the names of hydrocarbons end in '-ane'
Name of parent compound chain
- The name is of the hydrocarbon is determined by the number of carbon it has
- Alkane formula = CnH2n+2
Alkyl (Branched Hydrocarbons)
- Alkyl is an alkane which has lost one hydrogen atom
eg. CH4----> Ch3-- Naming: changing the "ane" ending of the original hydrocarbon to "yl"
eg. methane = CH4 ----> Methyl CH3-
Rule of Naming Alkyl
- include the carbon number at which the alkyl group is attached
- a dash- the name of the alkyl group
- finally, the name of the parent hydrocarbon chain, to which the alkyl group is attached
eg. CH3-CH-CH2-CH2-Ch3
'CH3 This is called 2-methylpentane
- Catherine
Alkenes & Alkynes
- carbon is able to form double/triple bonds with other carbon atoms
- when multiple bonds are formed, less hydrogen will attach to the carbon atom
- naming rules are similar to alkanes, the only difference is "ene"
Ex: CH2=CH2 ethene
CH2=CzH- CH3 propene/propane
Ex: Name the following compound.CH3-CH2-C=CH-CH3
|
CH2-CH3
Trans & Cis Butene
if 2 adjacent carbons are bonded by a double and have side chains attached to them, it is possible for 2 compounds to be made
Alkynes, with one or more triple bonds located between carbon atoms leads to an "unsaturated" hydrocarbon.
The ending is changed from "ane" for alkane and "ene" for alkene to "yne" for alkyne.
Check out this link for some extra help!
-Lauren
Tuesday, May 17, 2011
Electron Dot and Lewis Structures
Drawing Electron Dot and Lewis Structures
Each bond in the structural formula represents 2 electrons. All valence electrons must be used. Each element must have a full valence shell (8 electrons), except hydrogen which only needs 2 electrons.
Ex: C2H6 Carbon- 4e Hydrogen- 1e
A structural diagram is one that shows each bond as a line. Each line represents 2 dots. Lone pairs aren't shown in structural diagrams: H H
H-C - C -H
H H <----(structural lines connecting bottom and top H's with the C's.)
Lewis Structures
For ex: CCl4
3. Can't up the total number of valence electrons in a molecule. Adjust the number by subtracting one
electron, for every positive charge. Adding one for negative charges.
4. Find the number of valence electrons remaining.
5. Use the number of valence electrons remaining to complete the octets of the atoms bonded to the central atoms.
6. Then place any remaining electrons on the central atoms in pairs.
7. If the central has less than an octet, make multiple bonds.
8. Replace each pair of electrons engaged in a bond with a dash " - "
Check out this link for extra help!
http://www.youtube.com/watch?v=K7EAteDWxPQ
-Lauren
- the nucleus is represented by the Atomic symbol
- for individual elements you have to determine number of valence electrons
- electrons are represented by dots : .
- 4 orbitals (max. of 2 per each orbital)
- each orbital has 1 electron before they pair up
- the dots are placed into 4 groups of one/ 2 electrons, with 8 electrons representing a closed shell (noble gas configuration)
- the dots are placed on the 4 sides in pairs
Each bond in the structural formula represents 2 electrons. All valence electrons must be used. Each element must have a full valence shell (8 electrons), except hydrogen which only needs 2 electrons.
Ex: C2H6 Carbon- 4e Hydrogen- 1e
A structural diagram is one that shows each bond as a line. Each line represents 2 dots. Lone pairs aren't shown in structural diagrams: H H
H-C - C -H
H H <----(structural lines connecting bottom and top H's with the C's.)
Lewis Structures
- structural diagrams show the number of bonds in a compound
- electron dot diagrams show the electrons involved in the bond
- if you know the structure of a molecule it means you know which atoms are bonded to which
- H only needs 2 electrons
- CNOF (carbon, nitrogen, etc) always follow the octet rule
For ex: CCl4
- The central atom (H and F are never in the center)
- if a metal is present, place it in the center
- if a molecule has only 1 atom of a particular element and several atoms of another, the single one is the one in the center
- place the atom that needs the most electrons in the center
3. Can't up the total number of valence electrons in a molecule. Adjust the number by subtracting one
electron, for every positive charge. Adding one for negative charges.
4. Find the number of valence electrons remaining.
5. Use the number of valence electrons remaining to complete the octets of the atoms bonded to the central atoms.
6. Then place any remaining electrons on the central atoms in pairs.
7. If the central has less than an octet, make multiple bonds.
8. Replace each pair of electrons engaged in a bond with a dash " - "
Check out this link for extra help!
http://www.youtube.com/watch?v=K7EAteDWxPQ
-Lauren
Sunday, May 15, 2011
The History of the Periodic Table and the Periodic Table Families
The very first scientist arrange elements in order is an English chemist, John Newlands. He is the one who pioneered the discover of the periodic table. Newlands arranged the elements by their relative atomic weights in 1863.
The next year in 1864, Dmitri Mendeleev a Russian chemist, came up with the very first version of the peridic table. Unlike John Newlands, Mendeleev put the elements in order by similar properties in stead of their relative atomic mass. Mendeleev left blanks in the periodic table for the elements yet to be discovered.
Glen Seaborg is the last to make changes in the modern periodic table. Seaborg dicovered elements 94 to 102. Element 106 has been named after him.
For the organization of the periodic table, the horizontal rows are called a period. Vertical columns are called families or groups.
Alkali metals: highly reactive metals that are located in group 1 in the periodic table.
Alkaline earth metals: reactive metals that are located in group 2 in the peridoic table
Halogens : Non metals that are highly reactive and react with water, located in group 17.
Noble Gases: odourless, colourless, non metals that have low reactivity because their valence sheels are full. They are in group 18.
Lanthanide Series : elements 57-71
Actinide Series : elements 89-103, all are radioactive.
The next year in 1864, Dmitri Mendeleev a Russian chemist, came up with the very first version of the peridic table. Unlike John Newlands, Mendeleev put the elements in order by similar properties in stead of their relative atomic mass. Mendeleev left blanks in the periodic table for the elements yet to be discovered.
Glen Seaborg is the last to make changes in the modern periodic table. Seaborg dicovered elements 94 to 102. Element 106 has been named after him.
For the organization of the periodic table, the horizontal rows are called a period. Vertical columns are called families or groups.
Alkali metals: highly reactive metals that are located in group 1 in the periodic table.
Alkaline earth metals: reactive metals that are located in group 2 in the peridoic table
Halogens : Non metals that are highly reactive and react with water, located in group 17.
Noble Gases: odourless, colourless, non metals that have low reactivity because their valence sheels are full. They are in group 18.
Lanthanide Series : elements 57-71
Actinide Series : elements 89-103, all are radioactive.
Atomic History
Aristotle (384 BC – 322 BC)
- Believed you could divide matter an infinite number of times
- Believed world was made of earth, fire, water and air.
- These elements were acted upon by gravity and levity
Democritus (460 BC)
- Believed matter was made up of tiny particles called ATOMS
- Matter could not be divided indefinitely
- Could not prove his hypothesis
Lavoisier (1777)
- founded the law of definite proportions
- discovered oxygen and hydrogen
- reasoned that the ratio between elements would always be the same in a compound no matter how much of that compound was available.
Dalton (1800s)
Five Point Atomic Theory
- All matter is made up of atoms
- Atoms of a given element differ from the atoms of another element
- All atoms of a given element are identical
- Chemical reactions do not change the elements but change the way the elements are grouped together
- Atoms cannot be created, divided or destroyed through chemical process.
Henri Bequerel(1851)
- discovered radioactivity
- studied the effect of xrays on photographic film
- some chemicals decomposed and gave off penetrating rays
Thomson (1897)
- Discovered the electron
- Used a cathode ray tube to experiment with the magnetic deflection
- Created the plum pudding model
- This model states that negatively charged electrons exist randomly throughout an atom. No mention of protons or a nucleus.
Bohr
- Created the bohr model of the atom
- Electrons do not spiral around the nucleus – they orbit at certain allotted distances from nucleus
- Atoms radiate energy- jump from higher to lower orbits
- His model had protons, electrons and neutrons
Rutherford
- Changed the arrangement of particles in an atom
- Gold foil experiment- shot alpha particles through gold foil – some of them bounced back
- He concluded that atoms have a positive dense centre and electrons orbit outside it
- This was the first planetary model – electrons spin around the nucleus.
Millikan (1921)
- Discovered the negative charge on the electron
- Used the oil drop experiment and observed the speed of the particles
James Chadwick (1932)
- discovered the neutron
- Observed that previously thought gamma radiation was radiation from neutral particles
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