Have you ever wondered how you could be more productive? How could you organize your timetable or school notes effectively? Perhaps you had some money and needed to make a budget to allocate it properly?
Well, I'm willing to bet you ended up using either list if all tasks at hand are different or an Excel table if you would like to group some of them together neatly. Now you see back in the day, and we are talking really back like 1800s there was no excel and people still managed to survive, which is quite frankly mind-boggling to me.
But they still made tables to organize their time, finances, and some people like Mendeleev used tables to organize all kinds of different things. What did he choose to organize? Well, everything that builds up the world, all elements in one table! Quite the undertaking right? Let's see what he came up with and how did that hold up against the test of time!
- Mendeleev Organized the Elements of The Periodic Table: going over the history of the periodic table and learning about Mendeleev's discoveries.
- Organization of Elements in the Periodic Table: thorough explanation of the hierarchy and order of the periodic table.
- Periodic Table Organization Activity: detailed and thorough explanation on periods and groups alongside their subsets.
- Periodic Table Organized by Metals: explaining and defining metals, metalloids, and non-metals.
Mendeleev Organized the Elements of The Periodic Table
The periodic table of elements is an essential tool in the study of chemistry, and every high school student has encountered it at some point. However, where did the periodic table come from exactly? By the way , why is it called periodic anyway?
Starting from the Nineteenth century, scientists used a lot of parameters and criteria to identify and group elements. For example, German scientist Johann Wolfgang Döbereiner observed that Calcium, Barium, and Strontium have similar qualities thus named this set of three elements a triad. In 1863, British chemist John Newlands classified the known elements into seven groups of eight elements each and defined the law of octaves.
According to the law of octaves, every eighth element organized in descending order of its atomic masses will have similar properties.
Today this law is known to be false, however, this is still an important piece of chemistry history.
I am sure you know by now that, with anything in science, there is a lot of trial and error. The periodic table went through a similar process as well. Different scientists tried to put together a periodic table that represented all elements (both in nature and man-made). However, the man credited with contributing the most to the periodic table was Russian scientist Dimitri Mendeleev.
In 1869 Mendeleev proposed that the properties of the elements were a function of their atomic mass. The Russian scientist, alongside his colleague Meyer, constructed an eight-column table of elements, in which components with similar qualities were grouped.
Mendeleev's table, which grouped the elements in increasing order of atomic mass, demonstrated that the elements' attributes repeated themselves in exact order:
According to Mendeleev, the properties of elements are a periodic function of their atomic mass (periodic law).
As you will see below, Mendeleev's periodic table from 1871 is somewhat different from the one we currently use today, but holds key contribution to the modern periodic table.
What was so special about Mendeleev's periodic table? Well, he foresaw the discovery of new elements and provided places in his periodic table to accommodate them. However, in envisioning periodicity as a basic law determining the nature of the elements, he went considerably further than his predecessors.
Based on that revelation, he famously left an empty position in his table for elements that were left undiscovered if the qualities of a particular element didn't fit the general pattern. The Russian scientist would then name these "hypothetical" elements with prefixes such as eka, dvi, and tri. Those are Sanskrit for one, two and three.
Back then Mendeleev assigned those prefixes to eight unknown elements. For instance, eka-aluminium was named so because it was placed below aluminium on Mendeleev's table, this one later got renamed to Gallium.
It's interesting how he chose Sanskrit no? Not Latin, French, German, Russian or English. Sanskrit! That's so random - how come though?
Well, it is believed that Mendeleev, during his studies at St. Petersburg University in Russia, studied Sanskrit. Why would he use an ancient Indian language in his studies though?
The Sanskrit alphabet, which Mendeleev's mentor was well-versed in, was a periodic system itself: the arrangement of the Sanskrit alphabet explained how letters may join to produce sounds in the same way as the periodic table of elements demonstrates how distinct elements can mix to form compounds.
With success comes failures though. Remember the trial and error process I mentioned above? Well, our Russian scientists fell victim to it.
Unfortunately, there were some limitations to Mendeleev's periodic table. In fact, his table was unable to explain some things such as the fact that cobalt, despite having an atomic mass greater than that of nickel, has properties that could place it before this element. These inconsistencies made it difficult to have a proper understanding of the elements.
So as you can see that atomic mass is not a perfect predictor of elemental properties, what is more often used today is the proton number (also known as atomic number). The modern periodic table is up next, and we can see this manifestation there!
Organization of Elements in the Periodic Table:
As mentioned above, the periodic law was reexamined due to some inconsistencies in the categorization of elements based on atomic mass.
Periodic law today is based on the fact that the properties of elements are a function of their atomic number rather than their mass.
Now that we got the history out of the way, let's go into the nitty and gritty part of the periodic table: its organization and how to understand it!
Periodic Table Organization Activity:
The periodic table is a list of chemical elements ordered by their atomic number, qualities, and features.
The International Union of Pure and Applied Chemistry (IUPAC) has confirmed 118 elements, amongst which:
- 94 elements are dubbed as "natural" (as they were found in nature).
- 24 elements are dubbed as "synthetic" (as they were made artificially).
The periodic table organizes and localizes all known elements into groups, periods, blocks, metals, nonmetals, nonmetals, lanthanoids, and actinides based on their characteristics and relationships to one another.
Periodic Table: Groups
Groups are the columns of the periodic table. They indicate chemical elements with similar chemical and physical properties.
- Groups A (typical/representative elements): Each group is numbered from 1 to 8. The group number corresponds to the valence electrons. For example, the elements of group VII A all have the external electronic configuration s2p5.
- Group B (transition elements): They are arranged on a lower level than the period. The transition elements are all those that in the periodic table of chemical elements fall into groups ranging from 3 to 12.
Some groups have their own characteristics, let's check them out!
Group IA: Alkali Metals
Alkali metals are characterized by high reactivity, low ionization energy, low electronegativity and negative reduction potential. They tend to only form compounds in their +1 oxidation state.
Group IIA: Alkaline Earth Metals
Alkaline Earth Metals are soft and have low density, they are very reactive, although less than those of group 1, and form compounds only in the oxidation state +2.
Group VII: Halogens
Halogens are highly reactive elements, that when reacting with metals, form salts. For instance,
if we were to combine 2 Na, a metal with 2 Cl2, a halogen, we get 2 NaCl and a lot of heat. This is called the "salt lamp experiment". Here you lower molten sodium into the chlorine atmosphere and you get a bright orange light and some salt.
Group VIII: Noble Gases (or inert gases)
Noble gases are characterized by a closed electronic structure, a duet for helium, and an octet for the others. These configurations are particularly stable and explain their zero or poor reactivity. They are monoatomic, colourless, odourless, tasteless and non-flammable.
Periodic Table: Periods
The periodic table has seven horizontal lines known as periods. They are arranged in the order of their atomic numbers. They are related to the concept of principal quantum number, essentially the number of the row corresponds to the principal quantum of the valance electron orbitals. Confusing here is an example:
If the outermost orbital is called 5s you would get 5 as the principal quantum number and consequently, it will be in the 5th row of elements. Now if your element's outermost orbital is 3d this guy would be placed in the 3rd row, easy right?
Period: Rows on the Periodic Table
The first period is the shortest as it has only two elements (H and He) because the elements have electrons only in an s-type orbital. They represent the first energy level (n = 1).
The second and third periods have eight elements. The electrons here are only in the s and p orbitals. They represent the chemical elements of the second (n = 2) and third (n = 3) energy levels respectively.
The fourth and fifth periods have 18 elements, and the electrons here have d-type orbitals.
Starting from the 6th you can get f orbitals too.
Transition Metals:
Transition metals, are malleable and ductile, conduct heat and electricity and form positive ions.
Lantinides and Actinides: Inner-transition Metals
Inner-transition metals, as mentioned above, are an extension of group 3. They can be divided into two subcategories:
- Lanthanides: are found naturally in the Earth's crust except for
- Actinides: created in the laboratory and are radioactive in nature.
While lanthanides never exhibit more than two oxidation states and give essentially ionic compounds, actinides exhibit a greater number of oxidation states and the presence of oxidation states stabilizes covalent bonds and facilitates the formation of complexes.
Periodic Table Organized by Metals:
There are three types of elements that make up the periodic table, based on their chemical and physical properties: metals, metalloids and non-metals.
- Metals: solid at room temperature (Mercury is the exception - it is a liquid at room temperature). Metals are malleable and durable. They are furthermore, good heat and electricity conductors. Metals are found on the table's left side.
- Non-metals: these tend to be mostly gases and solids, but bromine is the one exception here. It is liquid at room temperature. They are terrible electricity conductors and generally have weak intermolecular forces present between their molecules.
- Metalloids (also known as semimetals): they are called this way because they have both properties of metals and non-metals (hence the "semi"). Their electrical conductivity is lower than that of metals but higher than that of non-metallics. They're on the table's left side, between metal and non-metal.
The Periodic Table is a rather complicated beast, and we could go over so much more about it, but I hope this was enough for you to get the most important parts of it. If you still want more keep reading our other articles on the topic!
Periodic Table Organization - Key takeaways
- The elements are ordered according to the increasing atomic number; the atomic number (indicated with the letter Z) indicates the number of protons present in the nucleus of the atom.
- In the periodic table there are 7 horizontal lines that is 7 periods. The period of an element indicates the energy level on which the valence electrons are placed.
- In the periodic table there are 18 vertical lines that is 18 groups. The groups of the periodic table have a double numbering: the first in Arabic numbers from 1 to 18; the second, more important, in Roman numerals from I to VIII. The number of valence electrons corresponds to the Roman numeral: thus, H, Na, K etc .. all have only one valence electron. vice versa, Ne, Ar, Kr etc ... all have eight valence electrons.
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