Electron Dot & Lewis Diagrams by Greg Sra
Electrons are represented by dots in electron dot diagrams. The nucleus is represented by the atomic symbol. There are 4 orbitals having at most 2 electrons per orbital. Each orbital is given an electron before it pairs up. The dots are put into 4 groups.With 8 electrons signifying a closed shell or noble gas.
Lewis Diagrams:
1) Firstly you must find out how many valence electrons are in your chosen elements. Adjust this number by subtracting an electron for each positive charge. Or by adding an electron for a each negative charge in the atom. Then count the electrons remaining.
** You want your atom to become stable, the only way to do this is by having 8 electrons in the outer shell. (Hydrogen only needs 2 electrons)
2) Then select your central atom. A central atom is the atom that is the farthest away from a closed shell. (Metal Ion goes in center if available) H&F are an exception.Place the electrons so they fill each orbital.
3) Use the remaining valence electrons to fill out the orbitals. Place remaining electrons on the central atom.
4) Make multiple bonds if the central atom is not an octet.
Covalent Compounds
Two atoms share a pair of electrons to create a full outer shell. This pair is called the Bonding Pair.
Lone pairs or non-bonding pairs are the pair of electrons which do not join together. Single bonds can be represented by 2 dots or a single line.
Lewis Diagrams:
1) Firstly you must find out how many valence electrons are in your chosen elements. Adjust this number by subtracting an electron for each positive charge. Or by adding an electron for a each negative charge in the atom. Then count the electrons remaining.
** You want your atom to become stable, the only way to do this is by having 8 electrons in the outer shell. (Hydrogen only needs 2 electrons)
2) Then select your central atom. A central atom is the atom that is the farthest away from a closed shell. (Metal Ion goes in center if available) H&F are an exception.Place the electrons so they fill each orbital.
3) Use the remaining valence electrons to fill out the orbitals. Place remaining electrons on the central atom.
4) Make multiple bonds if the central atom is not an octet.
Covalent Compounds
Two atoms share a pair of electrons to create a full outer shell. This pair is called the Bonding Pair.
HISTROY OF THE PERIODIC TABLE
IN THE BEGINNINGGGG
-people believed everything was made up of fire, earth, wind, and water.
However, a russian chemist Dimitri Mendeleev would be the first person to write a periodic table. He grouped different elements based on their properties.
PICS
-people believed everything was made up of fire, earth, wind, and water.
However, a russian chemist Dimitri Mendeleev would be the first person to write a periodic table. He grouped different elements based on their properties.
PICS
Periodic Table Trends
Periodic Trends
Metallic Properties: The properties of the elements change fro metallic to non-metallic going left to right across the periodic table.
The elements become more metallic going down a family in the periodic table.
Atomic Radius
Atomic radii of an atom increases going across a row left to right, it also increases going down a group.
Going left to right across a given period the atomic number (and number of protons) increases, and the positive charge on the nucleus increases.
Ionization Energy: is the energy need to completely remove an electron from an atom. Ionization energy increases going up and to the right. All noble gases have high ionized energy. Helium has the highest ionization energy while Francium has the lowest.
Electronegativity: Is the tendency of an atom to attract electrons from a neighboring atom. Electronegativity energy increases going across a row left to right. It decreases going down a group.
Reactivity: When a metal moves down a row and right it becomes more reactive. Non-metals are the opposite as once they go up a row they become more reactive.
Metallic Properties: The properties of the elements change fro metallic to non-metallic going left to right across the periodic table.
The elements become more metallic going down a family in the periodic table.
Atomic Radius
Atomic radii of an atom increases going across a row left to right, it also increases going down a group.
Going left to right across a given period the atomic number (and number of protons) increases, and the positive charge on the nucleus increases.
Ionization Energy: is the energy need to completely remove an electron from an atom. Ionization energy increases going up and to the right. All noble gases have high ionized energy. Helium has the highest ionization energy while Francium has the lowest.
Electronegativity: Is the tendency of an atom to attract electrons from a neighboring atom. Electronegativity energy increases going across a row left to right. It decreases going down a group.
Melting & Boiling Point: Elements from the centre have a higher boiling point and Noble Gases have
the lowest melting point.
blog workers on strike
blog posts wont be updated until the day before ms chen marks them. Then someone will step up to the plate and write the last 10000 blogs we missed.
Periodic Table - History
A necessary step to the construction of the periodic table was the discovery of the individual elements. All of elements including copper, lead, silver, gold, and mercury have been known for a while, Henning Brand's discovery of phosphporous was the first scientific discovery.
As 200 years passed by, chemists started regarding the properties of the elements. By 1869, 63 elements had been discovered.
As the number of known elements grew, scientists began to recognize patterns in properties and began to develop classification schemes.
Law of Triads
In 1817 Johann Dobereiner noticed that the atomic weight of strontium fell midway between the weights of calcium and barium, elements possessing similar chemical properties.
After the discovery of the halogen triad (chlorine, bromine, and iodine); and the dicovery of the alkali metal triad (lithium, potassium, and sodium); he proposed that the nature of the triads allowed the middle element to be the average of the two elements (atomic mass). This si known as the Law of Triads.
After the discovery of the halogen triad (chlorine, bromine, and iodine); and the dicovery of the alkali metal triad (lithium, potassium, and sodium); he proposed that the nature of the triads allowed the middle element to be the average of the two elements (atomic mass). This si known as the Law of Triads.
First Attempts At Designing the Periodic Table
The periodic table demonstrates the order of chemical elements based on their chemical and physical properties. The credit to the first "draft" of the periodic table has to be given to Beguyer de Chancourtois that positioned a cylinder based on increasing atomic weight which then led to the conclusion that the properties of elements are the properties of numbers and they should be organised based on that.Law of Octaves
In 1863, John Newland classified 56 elements into 11 groups based on their properties; physical and chemical. He said that after every 8 elements, the properties re-appear. He then propsed his version of the periodic table and the Law of Octaves. This law stated that any given element will exhibit analogous behavior to the eighth element following it in the table.
Demetri Mendeleev
Russian chemist that arranged te periodic table based on the atomic mass of elements; and he put the elements with similar characteristics and properties under eaach other. He left some gaps for elements that are yet to be dicoverred and he did note that they will be discoverred to fit in the gaps that share the same properties. Examples of elements include gallium, scandium and germanium.
Mendleev's periodic table was important because it possessed the means of "periodic law" which states the elements vary periodically with their atomic weight.
Mendleev's periodic table was important because it possessed the means of "periodic law" which states the elements vary periodically with their atomic weight.
Discovery of the Noble Gases
Argon was discoverred in 1895 by Lord Rayleigh. He noted that this element did not fit any of the groups previously organized by Mendeleev and Newlands. 3 years after that, Ramsey suggested it should be put in the group between chlorine and potassium in one family with helium. The referred to it as the "zero group" because they had no valence electrons. Ramsey then predicted the discovery of the properties of the element neon.
The Modern Periodic Table
After the disovery of plutonium by in 1940 by Seaborg, and the discovery of elements from 94 to 102, he made some changes during the 20th century. He also placed the actinide series below the lanthinide series in 1951. He was awarded the Nobel Prize in chemistry and an element was named after him (seaborgium).
Periodic Table - Families
Scientists group families of elements by their chemical properties. Each family reacts a different way with the outside world. Metals behave differently than gases and there are even different types of metals. Some don't react, others are very reactive, and some are metallic.
Usually, the colums of the periodic table are used to define families. The inert gases are all located in the far right column of the table.
- Alkali Metals
They are found in group 1 of the periodic table:
They are found in group 2 of the periodic table:
- Lanthanide and Actinide series
Usually, the colums of the periodic table are used to define families. The inert gases are all located in the far right column of the table.
Families
- Alkali Metals
They are found in group 1 of the periodic table:
- Highly reactive metals that do not occur freely in nature.
- These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements.
- Malleable, ductile, good conductors of heat and electricity.
- Softer than most other metals.
 |
| Sodium |
They are found in group 2 of the periodic table:
- Same properties as alkali metals but an ionization number of +2, making them very reactive, but less reactive than the alkali metals.
 |
| Magnesium |
- Transition elements are ductile and malleable, they conduct electricity and heat.
- Their valence electrons are present in more than one shell. This is why they often exhibit several common oxidation states
 |
| Gold |
- Non-metallic elements are found in group 17 of the periodic table.
- All halogens have 7 electrons in their outer shells, giving them an ionization number of -1.
 |
| Bromine |
- Group 18 of the periodic table.
- Ionization number of 0. This prevents them from forming compounds readily.
- All noble gases have 8 electrons in their outer shells, making them stable.
- Lanthanide and Actinide series
- All of them are found in group 3 of the periodic table, 6th and 7th periods.
- most of them are man-made (synthetic)
- Same properties as other metals
Subscribe to:
Posts (Atom)
