Trends on the Periodic Table

There are many different trends on the periodic table. Here is a list of the different trends:

1. Metallic Properties
2. Atomic Radius
3. Ionization Energy
4. Electronegativity
5. Reactivity 
6. Ion charge
7. Melting/Pointing Point
8. Density

Metallic Properties

- Metallic to non metallic = left to right

- Elements = more metallic going down a family in the periodic table

Atomic Radius

- Decreases going across a row left to right

- Increases going down a group

- Going left to right = atomic number, protons, and positive charge increases

- Increases in the number of electrons surrounding the nucleus

- All electrons have same average distance from the nucleus

- More protons = less distance between the electrons and the nucleus

General Trend

- Atomic size decreases left to right

- Increases down a column

Reactivity

- Most reactive metal = Francium

- Most reactive non metal = Fluorine

Ion Charge

- Depends on their group/column

Melting Point/Boiling Point

- Highest = The centre of the table

- Noble gases =  Lowest

- Left to right = increase (until the middle of the table)

Ionization Energy

- Needed to completely remove electrons from atoms

- Increases going up and to the right

- Noble gases have high ionization energy

- Helium has the highest IE

- Decreases going down

Electronegativity

- How much an atom wants to gain electrons

- Same trend as Ionization Energy

- High electronegativity attracts neighbouring atoms' electrons and might remove them completely

- High electronegativity = high ionization energy

- Fluorine is the most electronegative element

History of the Periodic Table

Here's a little bit of information on how the wonderfully organized periodic table was invented. Yes, it's true; the periodic table didn't always exist :p So, first of all, we needed know some elements before we could even organize them. By 1917 we had already discovered 52 elements and it was rapidly increasing. By 1863 a total of 62 elements were discovered. The first few attempts to organize them was in the 1920s but nothing really got done.

- In 1857, Willy Odling seperated the elements into 13 different groups based on their physical and chemical properties. It had its flaws but it was a good start.

- Between 1863 and 1866 a guy named John Newlands discovered that by ordering all the known elements by their masses, every eighth element had something in common. This became known as the Law of Octaves. However, this method did not allow him to predict new elements.

BREAKTHROUGH!! YAY :)

 (Nice hair hehe)

- In 1869 Dimitri Mendeleev organized the elements according to their mass and properties. When he did this, he realized he was on to something...and indeed he was. :p
- When he listed them according to their mass, he noticed that certain properties recur periodically. (Oooh so that's why it's called the periodic table)
- He then broke the list into rows (period) and columns (group)
*So in other words, Dimitri was the first to make a periodic table
- He was able to predict the properties and characteristics of undiscovered elements very accurately
- This allowed chemists to organize and understand their data + predict new properties (which is very useful!!)

Modern Periodic Table
- The periodic table we use today is organized according to atomic numbers. (Incase you didn't notice..)
- Periodic Law: Properties of the chemical elements recur periodically when the elements are arranged from lowest to highest atomic numbers.

Major Divisions in the Periodic Table
Period: The set of all elements in a given row going across the table.
Group/Family: The set of all elements in a given column going down the table.


Chemical Families
Now that we know a little more about the history of the periodic table, lets learn about the different groups and families that can be found on the table. As you can see in the above picture there are many different types of elements and each one is separated into their own little groups. Here's a little bit more information on the different families.

*In case you didn't look at the above picture...
Alkali Metal: Elements in the 1st column (except hydrogen).
Alkaline Earth Metals: Elements in the 2nd column.
Halogens: 2nd column from the end on the right hand side. Starting with fluorine.
Noble Gases: Far right side of the table starting with helium.
Lanthanides: Elements in the 1st row shown under the table, starting with lanthanum.
Actinides: Underneath the lanthanides, starting with actinium.


Metals
- Reflect light when polished.
- Shiny and metallic lustre.
- Opaque
- Good conductors of electricity and heat
- Flexible when in sheets
- Malleable (Hammered or rolled into sheets)
- Ductile (Drawn into wires)
- Solid at room temperature (Except mercury)
- Lose electrons


Non-Metals
- Gas, liquid, brittle solid at room temperature
- Poor conductor of heat and electricity
- Solids = dull to lustrous and opaque to translucent 
- 2 types of non metals:

• Very low electrical conductive 
• Fair to moderate conductivities

Semiconductor

- Non metal with electrical conductivity, it increases with higher temperature

- Metalloids/Semimetals have properties that look more like metals than non metals

- Metal conductivity decreases with increased temperature 

- Metalloid's conductivity increases with temperature

Electron Configuration (Orbitals, Valance Electrons, and Core Notation)

The electron configuration of an atom is a form of notation which shows how the electrons are distributed among the various atomic orbital and energy levels.  

before we start, you have to know these principles so you can fill the electrons correctly.
 

I.  Principle Quantum Number (n) and Sublevels

The number of sublevels that an energy level can contain is equal to the principle quantum number of that level.  So, for example, the second energy level would have two sublevels, and the third energy level would have three sublevels.  The first sublevel is called an s sublevel.  The second sublevel is called a p sublevel.  The third sublevel is called a d sublevel and the fourth sublevel is called an f sublevel.  Although energy levels that are higher than 4 would contain additional sublevels, these sublevels have not been named because no known atom in its ground state would have electrons that occupy them.

II.  Sublevels and Orbitals

An orbital is a space that can be occupied by up to two electrons.  Each type of sublevel holds a different number or orbitals, and therefore, a different number of electrons.  s sublevels have one orbital, which can hold up to two electrons.  p sublevels have three orbitals, each of which can hold 2 electrons, for a total of 6.  d sublevels have 5 orbitals, for a possible total of 10 electrons.  f sublevels, with 7 orbitals, can hold up to 14 electrons.  The information about the sublevels is summarized in the table below:

Table 3-6a - Orbital and Electron Capacity for the Four Named Sublevels
Sublevel	# of orbitals	Maximum number of electrons
s	1	2
p	3	6
d	5	10
f	7	14

III.  Total Number of Electrons per Energy Level

An easy way to calculate the total number of electrons that can be held by a given energy level is to use the formula 2n².   For example, the fourth energy level (n=4) can hold 2(4)² = 32 electrons.  This makes sense because the fourth energy level would have four sublevels, one of each of the named types.  The s sublevel hold 2 electrons, the p sublevel holds 6 electrons , the d sublevel holds 10 electrons and the f sublevel holds 14 electrons.  2 + 6 + 10 + 14 = 32, so the formula 2n² works!  We can summarize this information in the table below:

Table 3-6b Orbitals and Electron Capacity of the First Four Principle Energy Levels
Principle energy level (n)	Type of sublevel	Number of orbitals per type	Number of orbitals per level(n2)	Maximum number of electrons (2n2)
1	s	1	1	2
2	s	1	4	8
	p	3
3	s	1	9	18
	p	3
	d	5
4	s	1	16	32
	p	3
	d	5
	f	7

  

V.  Order of Filling Sublevels with Electrons

The next thing that you need to recall is the fact that the energy sublevels are filled in a specific order that is shown by the arrow diagram seen below:

Remember to start at the beginning of each arrow, and then follow it all of the way to the end, filling in the sublevels that it passes through.  In other words, the order for filling in the sublevels becomes; 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,7p.

So, how to find the numbers of valance electrons?

Its easy!  you just need to add all the electrons in s and p sublevel

Then, how do you write it in core notation.

First, you have to find the noble gas at the front role

Then, you add electrons until you get the number of electrons you want

eg. C = [He]2s²2p²

Isotopes and Molar mass

Before we start the lesson, its good for us to play this game.  It can help us to get a basic idea of isotopes and atomic mass

http://phet.colorado.edu/zh_TW/simulation/isotopes-and-atomic-mass

So, Isotopes are atoms which have the same atomic number but different mass numbers.   In Other words, they have the same number of protons but different numbers of neutrons.

The number of neutrons in an atom can vary within small limits.
Eg. there are three kinds of carbon atom ¹²C, ¹³C and ¹⁴C. They all have the same number of protons, but the number of neutrons varies.

	protons	neutrons	mass number
carbon-12	6	6	12
carbon-13	6	7	13
carbon-14	6	8	14

These different atoms of carbon are called isotopes.

Molar mass of a substance combined by isotopes
Eg.
Carbon can be formed by these isotopes.
90.% of carbon-12, 5.0% of carbon 13 and 5.0 % of carbon 14

We can calculate this particular substance's atomic mass by:
  12x0.90 + 13x  0.050 +14x0.050
=   12.15  (2 sig fig)
=   12g

Atomic Structure (Electron, neutrons, protonx)

Review from Science 10
Atoms are made up of 3 types of particles electrons , protons  and neutrons .  
These particles have different properties.  

• Electrons are tiny, very light particles that have a negative electrical charge (-).  
• Protons are much larger and heavier than electrons and have the opposite charge, protons have a positive charge.  
•  Neutrons are large and heavy like protons, however neutrons have no electrical charge.  

Each atom is made up of a combination of these particles. 

protons and neutrons form the nucleus and they are surrounded by the electron

*atomic number is the number of protons
*atomic mass is the number of protons and neutrons

Eg.  Helium
 It has 2 protons and 2 neutrons so its atomic number is 2 and its atomic mass is 4