Isotopes & Atoms

Scientists discovered that an atom contains 3 fundamental particles: Protons, neutrons, & electrons. All atoms of a given element are identical because they have they same number of protons & electrons. However, it does not mean that all atoms have the same number of neutrons.

   

Since all elements have different properties, scientists refer to the periodic table





 Each element is listed in squares in the periodic table which provides information about a particular element. Scientists know where to specifically look when they are trying to identify an element.







Scientists look for:
A= Atomic # (protons & electrons)
B=Ion charges
C= Abbreviation of element
D=Element
 E=Atomic mass

The only subatomic particle that does not appear on the Periodic Table is the Neutron. But it's no big deal since the Neutron can be easily found by using this simple formula. Atomic mass- Atomic Number = # of Neutrons.


And since ATOMS do NOT have the same number of Neutrons they are called Isotopes. Hydrogen has isotopes...



Same with Lithium...


Mass Spectrometers are used to determine the abundance & mass if the isotopes of elements.
 Or you can simply just use the formula:  mass x abundance = atomic mass. THIS video will give a Clear understanding of how to find atomic masses. Enjoy!

Quantum Mechanics

Bohr Theory

• The electron is a particle that must be in orbital in the atom

Quantum Theory

• The electron is the cloud of negative charge in a wave function
• Orbitals are areas in 3D space where the electrons most probably are
• The energy of the electrons is in it's vibrational nodes
• Photons are produced when high energy modes change into lower energy modes

Determining an elements chemical properties is it's electron configuration, particularly the valence shell electrons. The type of orbital the atom's outermost electrons reside determines the 'block' and the number of valence shell electrons determine the 'group'.

The total number of electron shells detemines the period it belongs and each shell is divided into sub-shells

Subshell:	S	G	F	D	P
Period
1	1s
2	2s				2p
3	3s				3p
4	4s			3d	4p
5	5s			4d	5p
6	6s		4f	5d	6p
7	7s		5f	6d	7p
8	8s	5g	6f	7d	8p

Through a group of lightest element to heaviest element, the outer shell electrons are all in the same orbital, with a very similar shape, but increasingly higher energy and distance from the nucleus. The outer shell, for instance, all have one electron in an s-orbital. In hydrogen, the s-orbital is the lowest possible energy state of any atom, the first.



 The different regions of the atomic table are named according to the sub-shell in which the last electron is...

S-Orbital
- Each Orbital holds two electrons
- Spherically symmetric around the nucleus
- Only has one orbital

P-Orbital
- There are 3 sub-orbitals
- Each Orbital contain 2 electrons
- In total, there are 6 electrons

D-Orbital
- There are 5 sub-orbitals
- Each orbital contains 2 electrons
- In total, there are 20 electrons

F-Orbital
- There are 7 sub-orbitals
- Each contain 2 electrons
-In total, there are 14 electrons

Here's a really helpful video to help understand electron configuration

Lets see if you can do some! (:

1. What is the electronic configuration for nickel?
2. What is the electronic configuration for Gold?
3 What is the electronic configuration for Zinc?

Answers
1. 1s2 2s2 2p6 3s2 3p6 3d8 4s2
2. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1 4f14 5d10
3. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰

Bohr's Model

The Bohr model: was introduced my Neils Bohr in 1913. He introduced that surronding the positively charged nucleus was electrons. His idea is somewhat similar to the solar system with the exception that electrostatic forces provide attraction not gravity. At some point Bohr and Rutherford's models were "combined" since Bohr's model is like a quantum physics based modification of Rutherford's model; people called it the "Bohr-Rutherford model. "

-Rutherford's model was inherently unstable

• Protons and Electrons should attract eachother

-Matter emits light when it is heated (backbody radiation)

•   Light travels as a photon

 . Energy photons carry depends on their wavelength
   e.g: radio stations such as the beat 94.5 <---- the 94.5 actually represents frequency radio waves
         (FM has more energy than AM)

These lines in the emission spectrum are unique set of lines for each element. Each line represents a Photon of light emitted from the excited atom. Bohr based his model on the energy (light) emitted by different atoms. Each atom has a specific spectra of light. To explain this emission spectra, he suggested that electrons occupy Shells or Orbitals

Bohr's Theory

- Electrons exist in orbits
- when they absorb energy they move to a higher orbital
- As they fall from a higher orbital to a lower one they release energy as a photon of light.


Here is an educational video that explains a bit more about Bohr's theory. :)

Chaper 1 Chemistry test!

Today in Chemistry 11, we had a test on Chapter 1 and it was great! (:

Atomic Theories

Today in Chem 11, we had an in depth lesson on something we learnt about in grade 10, Atomic theories!

There are many people, concepts and features that are important to know when learning Atomic theories, so here are a few important ones to learn:

Four Element Theory (Arostotal)
- Matter is made up of water, wind, earth and fire
- This theory of Arototal's lasted for 2000 years!
- But, isn't a scientific theory because is couldn't be tested against observation

Democritus (4000 BC)
- First mentioned Atoms, and said they were indivisible partices
- This theory was not a testable one though, it was a conceptional one
- There were not any mention of atomic neucleus or it constituients and can't be used to explain chemical reactions

Lavoiser (Late 1700's)
- Introduced the law of conservation of mass and the law of definite proportions
- Water is always 11 % Hydrogen and 89 % Oxygen

Proust (1799)
- Claimed that if a compound is broken down into it's constituients, the products exist in the same ratio as in the compound

Dalton (Early 1800's)
- Aoms are solid, indestructable spheres, just like billiard balls!
- Provides for differet elements
- Explains chemical reactions
- Does not explain isotopes, electricity, attraction, compulsion, etc..

JJ Thompson (1850's)
- Proposed the raisin bun model
- Solid, positive spheres with negative particles embedded in them
- First atomic theory to have positive (protons) and negative (electrons) charges
- Demonstrated existance of electrons using cathode ray tubes

Rutherford (1905)
- Showed that atoms have a positive, dense, centre with electrons outside it which resulted in a planetary model
- Suggested that atoms are mostly empty space

Density & Graphing

What is Density?

• The Density of an object is it's mass divided by it's volume 

Ex.  d = m/v (density = mass in kg divided by volume in L)

• Is usually expressed in Kg/L, Kg/m^3, or g/cm^3

Ex.  135Kg/65L = 2.077 ~ 2.01
                           = 2.01 Kg/L

Well, what about Graphing...? 

Graphing is pretty straight forward but we need to remember 5 very important things when faced with the task of putting one together:

1. Label axis' 
2. Create an appropreate scale
3. Don't forget the title!
4. Plot the data points
5. And finally use a line of best fit

• Three things can be done when working with a graphs.  #1, reading the graph.  #2, finding the slope.  #3, Finding the best fit line. 

Here's a video that will give you a good idea of what graphing in physics 11 is all about :)  

What's good about that video is that it gives you information about how to find slope AND area.  But just to recap...

Slope = Rise / Run or Y2-Y1 / X2-X1
Area of a triangle =1/2 (bh)
Area of a rectangle = l x w