Period Tables and Trends

• Elements close together on the periodic table display similar characteristics.
• There are 7 important periodic trends.

1. Reactivity
2. Ion charge
3. Melting point
4. Atomic radius
5. Ionization energy
6. Electronegativity
7. Density*

Reactivity


-Metals and non-metals show different trends.
-The most reactive metal is Francium and the most non reactive element is Flourine.



Ion Charge

-Elements ion charges depend on their group(columns)






Melting points

-Elements in the center of the table have the highest melting point.
-Noble gases have the lowest melting point; starting from left to right melting point increases. (until middle of the table.



Atomic Radius
-Atomic radius decreases to the up and the right.
-Helium has the smallest atomic radius.
-Francium has the largest atomic radius.



Ionization energy
- The energy needed to completely remove aan electron from and atom.
- It increases going up and to the right.
- All Noble gases have high ionization energy.
- Helium has the highest ionization energy.
- Francium has the lowest ionization energy.
- Opposite trend of Atomic Radius.



Electronegativity

- Electronegativity is how much atoms want to gain electrons.
- Same trend as ionization energy.



- Ben Suratos

Isotopes and Atoms

What Does the Periodic Table Reveal:

The above image shows that the element Krypton has: 

• An atomic number of 36 
• 36 Protons in the nucleus 
• An atomic mass of 83.80 
• This atomic mass is the weighted average of the mass of all the isotopes   
• It also reveals the number of neutrons  
• Atomic Mass(84) - Atomic Number/ Number of Protons(36) 
• 48 neutrons in the nucleus

What are Isotopes:

Isotopes are any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different number of neutrons in the nucleus, or different atomic weights. 


For example, there are three types of hydrogen: 

• Hydrogen (Atomic Number: 1/ Atomic Mass: 1)
• Deuterium (Atomic Number: 1/ Atomic Mass: 2)
• Tritium (Atomic Number: 1/ Atomic Mass: 3)    

As you can see, each of these different types of hydrogen have identical atomic numbers, therefore the number of protons in the nucleus is consistent. However, the distinction lies in their different atomic mass or the difference in neutrons. These are isotopes. 

What are Mass Spectrometers: 

Mass spectrometers are graphs used to determine the abundance and mass of the isotopes of an element. In these graphs the y-axis charts the relative abundance versus the mass in the x-axis. If the relative abundance is multiplied by the mass, as identified in each isotope, and this is done for all the other isotopes of an element, the abundance can be calculated to 100%. 

For example, zirconium: 

(relative mass x mass) + (relative mass x mass)... 

(0.515 x 90.00) + (0.112 x 91.00) + (0.171 x 92.00) + (0.174 x 94.00) + (0.0280 x 96.00)

 = 91.3 amu or 91.3 atomic mass units 


-Simon Sierra

Quantum Mechanics

Bohr Theory:

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

Quantum Theory:

• The electron is a cloud of negative charge or a wave function
• Orbitals are areas in 3d space where the electrons are must probably are. The energy of the electron is in its vibrational mode. Like notes on a guitar string.
• Photons are produced when high energy modes change to lower energy modes

S orbitals:

Each orbital holds 2 electrons

P-orbitals:

• There are 3 sub orbitals
• Each contains 2 electrons
• Total electrons = 6

D-orbitals:

• There are 5 sub orbitals
• Each contains 2 elecrons
• Total electrons = 10

F-orbitals:

• There are 7 sub orbitals 
• Each Contain 2 electrons 
• Total electrons = 14

The Electron Configuration: 


Electron configurations in quantum physics are written in the from orbitalelectrons.  The formula for hydrogen, for example, is 1s1 and the formula for helium is 1s2. Cobalt, which is a much more complicated element, has the formula 1s22s22p63s23p64s24p63d1. 


Examples: Neon - 1s2, 2s2, 2p6