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Atoms are the basic building blocks of matter
Atoms are the basic building blocks of matter
Elements are pure substances and cannot be broken down into smaller substances
Elements are pure substances and cannot be broken down into smaller substances
It is for this reason that we consider the terms atoms and elements interchangeable
It is for this reason that we consider the terms atoms and elements interchangeable
Each atom is made up of three parts:
Each atom is made up of three parts:
- Protons
- Electrons
- Neutrons
Let's take a closer look at an element. The picture below shows one atom of carbon, the basic building block of our DNA
Let's take a closer look at an element. The picture below shows one atom of carbon, the basic building block of our DNA
The protons are positively charged and are located inside the nucleus (the center)
The protons are positively charged and are located inside the nucleus (the center)
The neutrons have no charge and are also located inside the nucleus
The neutrons have no charge and are also located inside the nucleus
The electrons are negatively charged and circle around the atom in a special cloud
The electrons are negatively charged and circle around the atom in a special cloud
The periodic table of elements was developed around the 1860s by a Russian scientist named Dmitri Mendeleev.
The periodic table of elements was developed around the 1860s by a Russian scientist named Dmitri Mendeleev.
Dmitri found a way to easily organize them based on special properties and patterns.
Dmitri found a way to easily organize them based on special properties and patterns.
Let's take a look at how elements are organized on the Periodic Table of Elements.
Let's take a look at how elements are organized on the Periodic Table of Elements.
The first thing you notice about the table is the different colors. Each color represents a special "family" those elements belong to (more on this later)
The first thing you notice about the table is the different colors. Each color represents a special "family" those elements belong to (more on this later)
Next, you probably notice a bunch of letters and numbers all over the table. These letters and numbers help not only identify the element, but it will also predict how it will act if we combine it with other elements.
Next, you probably notice a bunch of letters and numbers all over the table. These letters and numbers help not only identify the element, but it will also predict how it will act if we combine it with other elements.
**NOTE: each periodic table may be slightly different**
**NOTE: each periodic table may be slightly different**
Let's learn how to read the periodic table.
Let's learn how to read the periodic table.
Each element has its own box called the "element box". This box contains a lot of information (see below)
Each element has its own box called the "element box". This box contains a lot of information (see below)
Each element box will tell you how many protons the element has and its name.
Each element box will tell you how many protons the element has and its name.
Using the other information, we can also figure out how many neutrons it has AND how many electrons it has.
Using the other information, we can also figure out how many neutrons it has AND how many electrons it has.
Here is how you can figure out how many neutrons and electrons an element has.
Here is how you can figure out how many neutrons and electrons an element has.
Let's use carbon as an example.
Let's use carbon as an example.
Atomic Number = Protons = Electrons
Atomic Number = Protons = Electrons
Atomic Number = 6, Protons = 6, Electrons = 6
Atomic Number = 6, Protons = 6, Electrons = 6
Mass Number - Atomic Number = Neutrons
Mass Number - Atomic Number = Neutrons
(12.01) - (6) = 6 neutrons
(12.01) - (6) = 6 neutrons
Carbon's Element Box
Aside from element boxes, the periodic table is also divided by periods and groups
Aside from element boxes, the periodic table is also divided by periods and groups
Periods are the rows on the periodic table.
Periods are the rows on the periodic table.
These rows represent energy levels (electron shells).
These rows represent energy levels (electron shells).
One periodic pattern is as you move from top to bottom, the energy levels of the elements increase
One periodic pattern is as you move from top to bottom, the energy levels of the elements increase
For example, Lithium (#3) has less energy than sodium (#11)
For example, Lithium (#3) has less energy than sodium (#11)
There is another periodic pattern. As you move from left to right the element is more likely to combine (react) with other elements
There is another periodic pattern. As you move from left to right the element is more likely to combine (react) with other elements
For example, Lithium (#3) is generally less reactive than Fluorine (#9)
For example, Lithium (#3) is generally less reactive than Fluorine (#9)
Groups on the periodic table divide elements based on special traits.
Groups on the periodic table divide elements based on special traits.
Groups are also called families.
Groups are also called families.
These groups are usually numbered 1-18 at the top of the periodic table.
These groups are usually numbered 1-18 at the top of the periodic table.
There are many different families, but the most important ones are listed below.
There are many different families, but the most important ones are listed below.
Red -- 1st group; called the alkali metals
Red -- 1st group; called the alkali metals
Orange -- 2nd group; called the alkali earth metals
Orange -- 2nd group; called the alkali earth metals
Blue -- 16th group; called the chalogens
Blue -- 16th group; called the chalogens
Purple -- 17th group; called the halogens
Purple -- 17th group; called the halogens
Aqua -- 18th group; called the noble gases
Aqua -- 18th group; called the noble gases
The last big pattern on the periodic table is metals, nonmetals, and metalloids.
The last big pattern on the periodic table is metals, nonmetals, and metalloids.
Each element falls into one of these categories. Based on where the element is, we can further predict how the element will combine (bond/react) with other elements.
Each element falls into one of these categories. Based on where the element is, we can further predict how the element will combine (bond/react) with other elements.
Below are two pictures that help summarize this pattern.
Below are two pictures that help summarize this pattern.
Advanced Topics
Advanced Topics
Atomic Model Theory
Atomic Model Theory
Over the years, scientists have had to update their theories on how atoms look like and how they behave based on new discoveries. In addition, they have had to update diagrams used to discuss ideas.
Over the years, scientists have had to update their theories on how atoms look like and how they behave based on new discoveries. In addition, they have had to update diagrams used to discuss ideas.
Currently, we use Bohr's Model to illustrate how atoms bond with each other.
Currently, we use Bohr's Model to illustrate how atoms bond with each other.
Isotopes
Isotopes
Isotopes are elements with same atomic number, but DIFFERENT number of neutrons.
Isotopes are elements with same atomic number, but DIFFERENT number of neutrons.
The average number of isotopes and how common they are help us figure out what the atomic mass
The average number of isotopes and how common they are help us figure out what the atomic mass
Valance Electrons
Valance Electrons
Valence electrons are the outermost electrons located in the electron orbit (shell)
Valence electrons are the outermost electrons located in the electron orbit (shell)
Elements use their valance electrons to combine (bond/react) with other elements
Elements use their valance electrons to combine (bond/react) with other elements
Elements inside each group have the same number of valance electrons as the group number
Elements inside each group have the same number of valance electrons as the group number
For example, all elements inside the 1st group have 1 valence electron
For example, all elements inside the 1st group have 1 valence electron
***NOTE: Helium has 2 valence electrons even though it is in the 8th group***
***NOTE: Helium has 2 valence electrons even though it is in the 8th group***
***NOTE: All elements with 8 valence electrons DO NOT BOND with other elements***
***NOTE: All elements with 8 valence electrons DO NOT BOND with other elements***
Types of Bonds
Types of Bonds
The diagram below illustrates how elements can bond in different ways.
The diagram below illustrates how elements can bond in different ways.
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