Table of Elements, Valence Electrons, Mole Conversions

Periodic Table of elements

The periodic table of elements is a chart that contains all known elements along with their atomic number, atomic mass, and the symbol of the element. Here is a great interactive chart.
http://chemicalelements.com/
external image periodic_table.gif

Picture from http://south.mpls.k12.mn.us/Periodic_Table.html

The atomic number is the number of protons and electrons in an element. If you subtract the atomic number from the atomic mass you are able to find the amount of neutrons in an element.

Valence electrons

Valence electrons are the electrons in the outer shell of an atom. An atom wants to have a full outer shell so these electrons are attracted to other atoms so they can fill up the outer shell. The number of velance electrons is the key to how an atom will bond with another.

A very useful tool when working with elements is the electron dot diagram.
These are useful because they give you a visual of the electron shells in an atom.  They will give you the ability to determine the type(s) of covalent bonds that an element may make in certain situations. Here is an example.
external image lewis-dot-diagram.gif
Picture from http://www.green-planet-solar-energy.com/lewis-dot-structure.html


Parts of an Atom/Sub-Atomic Particles:

An atom is made of of a nucleus, shells or orbits, and three types of sub-atomic particles: Neutrons, Protons, and electrons. Neutrons are neutral particles, and carry no charge. Protons carry a positive charge, and Electrons carry a negative charge. The nucleus of an atom is made up of a number of protons and neutrons, and the electrons orbit the nucleus in "shells".

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Each shell or orbit of an atom contains a certain number of electrons, depending upon which element it is. Each atom has a desire to have a full outer, or valence, shell, which means it wants to have the maximum possible amount of electrons possible on it's outermost shell. The number of electrons on each shell is uniform, as is shown in this chart:

Shell
Number of Electrons
1
2 Electrons
2
8 Electrons
3
8 Electrons
4
18 Electrons
5
32 Electrons
6
50 Electrons




Mole conversion


To understand mole conversions it is helpful to first understand what a mole is. Wikipedia states that a mole is unit of measurement for the amount of substance or chemical amount. A mole is used to show the number of molecules/mole; ions/mole; nuclei/mole; electrons/mole. The number that is used was discovered by Avogadro is 6.02 x 10(exponent)23. Well that’s a big number, what is it good for? This is used for mathematical conversions between the number of atoms, molecules, mass, or volume of a given substance. Here is a video explaining how mole conversions are done.


Isotopes

An isotope is a variation of an element, which will have the same number of protons in the nucleus, but has a different number of neutrons.

Chemical Bonds

There are three types of chemical bonds: Ionic, Covalent, and Metallic.

Ionic Bonds: An ionic bond occurs when two elements transfer electrons and create ions which attract each other. An example of this is NaCl. Na, or Sodium, has 1 electron on it's outermost shell, which it wants to get rid of. Cl, or Chlorine, has seven electrons on it's outermost shell, and needs one more electron to have a full valence shell. When these two elements bond, Sodium (Na) transfers it's one extra electron to Chlorine's (Cl) outermost shell, creating NaCl, or Sodium Chloride.

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Covalent Bonds:

A covalent bond is the strongest type of chemical bond. It occurs when two elements bond by sharing electrons. An example of this is H2O. Oxygen (O), has six electrons in it's outermost shell. Hydrogen (H) has one electron on it's one shell. When the two atoms of Hydrogen connect to the atom of Oxygen, they each share their one electron with the outermost shell of Oxygen's atom, which has six electrons. This gives Oxygen the two extra electrons it needs to have a full valence shell, and creates a strong bond and the element H2O, also known as water.

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Metallic Bonds:

A metallic bond is the weakest type of chemical bond. A metallic bond occurs when two metals bond and form a common electron cloud, which is a cluster of shared electrons.

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Application 

The table of elements applies to my career because it is the basis for chemistry. Chemistry is really the science that deals with these elements and how they react with one another. One way chemistry is used in the field is when energy is converted. For example chemistry is used in the making ethanol and it is converted from chemical energy to physical energy when you burn it in your car to create movement.