1. The Periodic Table Chapter 12
Now that we have learned about the Modern Atomic theory and understand what an atom is and what makes it up, and how it can be manipulated into different forms of itself. Let’s take a look at how the Periodic Table is organized and how this form of organization was developed.
Chapter 12
The Periodic Table

2. Section 1
Elements are arranged on the periodic table according to their properties.
First we should look at the periodic table and know that it is comprised of different elements, these elements are arranged on the periodic table according to their properties. So who came up with how to organize elements on the periodic table?

3. Discovering a Pattern
Dmitri Mendeleev, a Russian chemist, discovered a pattern to the elements in 1869.
Mendeleev arranged the elements by properties, and then by increasing atomic mass.
He noticed that when he arranged the elements according to mass, those with similar properties formed a repeating pattern.
Mendeleev found that the element’s properties followed a pattern that repeated itself every 7 elements.
He called his element arrangement a periodic table. Periodic means it happens at regular intervals.
In 1869 a Russian chemist knowing as Dmitri Mendeleev discovered a pattern to the elements. He arranged the elements by properties and then by increasing atomic mass. He noticed that when he arranged the elements according to their mass, those with similar properties formed a repeating pattern. Mendeleev found that the element’s properties followed a pattern that repeated itself every seven elements. He called his element arrangement the periodic table. Periodic by definition mean it happens at regular intervals in this case it was seven.

4. Changing the Arrangement
The periodic law states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements.
Mendeleev helped to really develop the periodic law which states that the repeating of chemical and physical properties of elements change periodically with the atomic number of the elements. Wait a minute, didn’t Mendeleev organize his table by atomic mass? Yes! However during Mendeleev’s time the proton had not been discovered so today the table is organized by atomic number rather than mass, surprisingly there are not that many difference in the order of the elements. Mendeleev even left spaces on the table to account for elements that have not been discovered yet, but he believed they would be discovered and he could explain their properties and he was right!

5. The Periodic Table and Classes of Elements
Elements are classified as metals, non-metals, and metalloids according to their properties.
Most of the elements are metals
Metals are found on the left and center of the periodic table.
Metals tend to be shiny, malleable, and ductile, and conductive.
Elements on the table are classified as metals, non-metals, and metalloids according to their properties. Most of the elements are metals and are found on the left and center of the periodic table. Metals tend to have physical properties of being shiny, malleable, ductile, and conductive. Remember malleable means the ability to be hammered into thing sheets and ductile is the ability to be drawn into wire, hopefully you remember that conductivity is the property that allows heat and energy or electricity to easily flow through the matter.

6. The Periodic Table and Classes of Elements
Non-metals are found on the right side of the periodic table.
Non-metals tend to have properties that are the opposite of metals. (dull, non-conductive, brittle)
Most non-metals are gases at room temperatures.
Non-metals are found on the right side of the periodic table. Non-metals tend to have properties that are the opposite of metals so that means they are dull, non-conductive, and brittle or they may break easily. Most non-metals are gases at room temperatures.

7. The Periodic Table and Classes of Elements
Metalloids can be found along the zigzag line that separates metals from non-metals
Metalloids have some metal properties and some non-metals properties.
The third classification of elements fall between the metals and the non-metals along the zig-zag line that separates the other two groups. And appropriately. Metalloids have some metal properties and some non-metal properties.

8. Decoding the Periodic Table
Each square on the periodic table contains the following information:
a. Chemical symbol
b. Atomic number
c. Atomic mass
d. Element name
Now let’s look at an individual square on the periodic table. Each square on the table contains the following information a Chemical symbol, Atomic number, Atomic mass, and an element name. Here you see that the chemical symbol is Mg, the atomic number is 12 so it has 12 protons and if it is a neutral atom 12 electrons, this element has an atomic mass of which is the average of all known isotopes which shows why it is a decimal and not a whole number. And that this element is known as magnesium.

9. Decoding the Periodic Table
Rows of elements are called periods.
Left to Right, Horizontal
The chemical and physical properties in a row follow a repeating pattern. The properties change gradually as you move from left to right across the period.
The elements in a column on the table are in a group or family.
Vertical, up and down
The members of a groups all have the same number of electrons in their outermost energy level (valence electrons).
The periodic table is also organized into rows and columns. Rows of elements are called period and they go from left to right or horizontal. The chemical and physical properties in a row follow a repeating pattern. The properties change gradually as you move from left to right across the period. There are seven periods on the periodic table. The elements in a column on the table are in a group or family and they are vertical or up and down. The members of a group all have the same number of electrons in their outermost energy level these are known as valence electrons.

10. Tomorrow…
Be ready for a CHECK UP first thing tomorrow! This is how I will know if you are:
Doing your homework!
Understand the content
And what we need to review and reinforce going forward!
Now…
Use your checklist to make beginning flashcards, you can also look at questions that we discussed in class today.
We will come up with more flashcards during opening discussion tomorrow.

11. Section 2 Elements are grouped by properties
Now that we know how the overall periodic table was developed an organized, lets look at some of the individual groups and special elements on the periodic table. Elements on the table are grouped by their properties.

12. Grouping the Elements
The properties of the elements in a group are similar because the atom of the elements have the same number of electrons in their outermost energy level.
The electrons that occupy the outermost energy level of an atom are called the valence electrons.
The outermost energy level is considered full if it contains 8 electrons. The energy level may actually be capable of holding more than 8, but once it gets 8 electrons, it is stable.
First energy level is full when it has 2 electrons.
The properties of elements in a group are similar because the atom of the elements have the same number of electrons in their outermost energy level. The electrons that occupy the outermost energy level of an atom is called the valence electrons. The outermost energy level is considered full if it contains 8 electrons. The energy level my be able to hold more than 8 but one it gets 8 it is considered stable. There is one exception. The first energy level can only hold two valence electrons because of its close proximity to the nucleus and therefore is considered full when it has two electrons.

13. Grouping the Elements
In an effort to get to 8 valence electrons, atoms will take, give, or share valence electrons from other atoms. Atoms that do this are considered reactive.
In an effort to get 8 valence electrons, atoms will take, give, or share valence electrons from other atoms. Any atoms that do this are considered reactive. The closer the atom is to becoming stable the more reactive it is. We will look more at the process of atoms giving, taking, or sharing valence electrons in an upcoming unit.

14. Grouping the Elements
Group 1 is known as the alkali metals. These are the most reactive elements on the periodic table. They are so reactive because they easily give away their one valence electron.
Group 2 is known as the alkaline-Earth metals. These are not quite as reactive as the group 1 metals because the group 2 metals have 2 valence electrons.
Now let’s look at each of the groups on the periodic table. Group 1 is known as the alkali metals. These are the most reactive elements on the periodic table. They are so reactive because they easily give away their one valence electron.
Group 2 is known as the alkaline-Earth metals. These are not quite as reactive as the group 1 metals because the group 2 metals have 2 valence electrons.

15. Grouping the Elements
Groups 3-12 are the transition metals. Their properties vary (1 or 2 valence e-)
Some transition metals from periods 6 and 7 appear at the bottom of the table instead of in the middle of the table with the rest of their period. These are the Lanthanides and Actinides
The Lanthanides and the Actinides were pulled out so the table would not be too wide.
Actinides are radioactive (also synthetic)
Groups 3-12 are the transition metals. Their properties vary (1 or 2 valence e-)
Some transition metals from periods 6 and 7 appear at the bottom of the table instead of in the middle of the table with the rest of their period. These are the Lanthanides and Actinides
The Lanthanides and the Actinides were pulled out so the table would not be too wide.
Actinides are radioactive (also synthetic)

16. Grouping the Elements
Group 13 is the Boron Group. (3 valence e-) reactive
Group 14 is the Carbon Group. (4 valence e-) reactivity varies
Group 15 is the Nitrogen Group. (5 valence e-)
Group 13 is the Boron Group. (3 valence e-) reactive
Group 14 is the Carbon Group. (4 valence e-) reactivity varies
Group 15 is the Nitrogen Group. (5 valence e-)

17. Grouping the Elements
Group 16 is the Oxygen Group. (6 valence e-) reactive.
~20% of air is oxygen and it is needed for combustion.
Group 16 is the Oxygen Group. (6 valence e-) reactive.
About 20% of air is oxygen and it is needed for combustion.

18. Grouping the Elements
The Halogens are very reactive gases because they have 7 valence electrons, which means they only need to take one to become stable.
The Halogen have similar chemical properties, but their physical properties are different.
The Halogens are very reactive gases because they have 7 valence electrons, which means they only need to take one to become stable.
The Halogen have similar chemical properties, but their physical properties are different.

19. Grouping the Elements
Group 18 is the Noble Gases. They have filled outermost energy level and are considered non-reactive.
Group 18 is the Noble Gases. They have filled outermost energy level and are considered non-reactive.

20. Grouping the Elements
Hydrogen is set apart because its properties do not match the properties of any other element.
Hydrogen is placed above Group 1 because it does have one valence electron just like all the other members of Group 1.
Even though hydrogen is placed on the left side of the periodic table with metals, it is a non-metal.
Hydrogen is the most abundant element in the universe.
Hydrogen is set apart because its properties do not math the properties of any other element.
Hydrogen is placed above Group 1 because it does have one valence electron just like all the other members of Group 1.
Even though hydrogen is placed on the left side of the periodic table with metals, it is a non-metal.
Hydrogen is the most abundant element in the universe.