What is the Periodic Table?
The periodic table is just a table full of elements arranged by their atomic number. It's arranged in rows so that elements with similar atomic structures appear to be in columns.
The rows on a periodic table are horizontal, or left to right, and are also called Periods.
The columns on a periodic table are vertical, or up and down, and are also called Groups or Families.
History of the Periodic Table
By 1860, 60 element had already been discovered. the Element symbols, atomic numbers, and properties had all been recorded in a book, but scientists wanted an easier way to organize the elements. However, since different chemists used different isotopes, everyone had a different mass recorded for the same element.
This was a problem, so in 1860, the first ever International Congress of Chemists met to set the properties for all 60 elements, along with the atomic mass.
Dimitri Mendeleev was a Russian chemist, and the first to try and organize the periodic table. He placed all the elements on notecards with their properties, and then tried to organize it by property. That's when he noticed that the elements were also being ordered by increasing atomic mass, and that other pattern's were starting to appear too at regular intervals. He named the table "Periodic", because it means repeating pattern.
Mendeleev left blank spaces in his table because he felt other elements had yet to be discovered, and he was right! Because of where the spaces were located he could predict what the atomic mass and properties of the elements were, and he predicted right for Sc, Ga, and Ge.
However, he did make a mistake when he put Iodine and Tellurium on the table because when he did so, he put them according to their properties instead of the atomic mass like he did the others.
Henry Moseley is a British chemist, and he decided to fix all the problems in Medeleev's table by rearranging elements on atomic number rather than atomic mass. He also solved the Iodine/Tellurium problem!
Moseley created the periodic law which states that the physical and chemical properties of the elements are a function of their atomic numbers. Which basically means that if elements are put in order of their atomic number, then then they will fit into a certain column, or family, that has certain characteristics.
Ex. Reacts with water
Periodic Trends
There are four different kinds of periodic trends, Atomic Radii, Ionization Energy, Electronegativity, and Electron Affinity.
The periodic table is just a table full of elements arranged by their atomic number. It's arranged in rows so that elements with similar atomic structures appear to be in columns.
The rows on a periodic table are horizontal, or left to right, and are also called Periods.
The columns on a periodic table are vertical, or up and down, and are also called Groups or Families.
History of the Periodic Table
By 1860, 60 element had already been discovered. the Element symbols, atomic numbers, and properties had all been recorded in a book, but scientists wanted an easier way to organize the elements. However, since different chemists used different isotopes, everyone had a different mass recorded for the same element.
This was a problem, so in 1860, the first ever International Congress of Chemists met to set the properties for all 60 elements, along with the atomic mass.
Dimitri Mendeleev was a Russian chemist, and the first to try and organize the periodic table. He placed all the elements on notecards with their properties, and then tried to organize it by property. That's when he noticed that the elements were also being ordered by increasing atomic mass, and that other pattern's were starting to appear too at regular intervals. He named the table "Periodic", because it means repeating pattern.
Mendeleev left blank spaces in his table because he felt other elements had yet to be discovered, and he was right! Because of where the spaces were located he could predict what the atomic mass and properties of the elements were, and he predicted right for Sc, Ga, and Ge.
However, he did make a mistake when he put Iodine and Tellurium on the table because when he did so, he put them according to their properties instead of the atomic mass like he did the others.
Henry Moseley is a British chemist, and he decided to fix all the problems in Medeleev's table by rearranging elements on atomic number rather than atomic mass. He also solved the Iodine/Tellurium problem!
Moseley created the periodic law which states that the physical and chemical properties of the elements are a function of their atomic numbers. Which basically means that if elements are put in order of their atomic number, then then they will fit into a certain column, or family, that has certain characteristics.
Ex. Reacts with water
Periodic Trends
There are four different kinds of periodic trends, Atomic Radii, Ionization Energy, Electronegativity, and Electron Affinity.
Atomic Radii
Half the distance between nuclei in covalently bonded diatomic molecules Decrease across Increase down |
Ionization Energy
Energy required to remove electrons from atoms Increase across decrease down |
Electronegativity
measure of ability of an atom in a chemical compound to attract electrons Increase across Decrease down |
Electron Affinity
How much the element wants and electron Increase across Decrease down |
If you are given four elements and you are trying put them in order based on their, let's say, electronegativity, all you really need is a periodic table and your fingers. I, however, prefer to use paper ball as my markers instead.
First you need to locate and put your finger, or paper ball, or other type of marker, over the elements your are looking for. The you simply go from the left to the right across the table and based on their trends, which for electronegativity it increase from left to right, and rank them as you go. The only time you go from top to bottom is if you have two or more elements in the same column.
You use the same process of ranking them for every trend, just make sure you pay attention to how the trend works.
First you need to locate and put your finger, or paper ball, or other type of marker, over the elements your are looking for. The you simply go from the left to the right across the table and based on their trends, which for electronegativity it increase from left to right, and rank them as you go. The only time you go from top to bottom is if you have two or more elements in the same column.
You use the same process of ranking them for every trend, just make sure you pay attention to how the trend works.