There are 118 elements listed on the periodic table and there are 5 green elements. Here are 5 green elements and their importance.
Si: Silicone is the second element of the periodic table. It has 14 protons,14 electrons with an atomic weight 28.0885.
    The key property of silicon is that it is a semiconductor.
This means that its conductivity changes according to light striking the material.
Some examples of semiconductor devices are solar cells, LEDs, computer processors and integrated circuits.
  Cd: Cadmium is the 49th element on the periodic table with a mass of 112.41 (the most abundant), 92 protons, and may lose 1 or 2 electrons
Since the elements were first discovered there has been some dispute over the ordering of the columns in the table from left to right.
Currently, the official ordering of elements in mass number increases as you move down any given column.
The periodic table is useful to know because it helps you memorize all 118 elements in an easier way. It also gives us a better understanding on how particular groups of these elements behave.
Here are the some of my bests:
Hydrogen: H
Hydrogen is the first in the periodic table, which means it's the smallest. Smaller than helium (second smallest) and even smaller than lithium (third smallest). And we assume a lot of elements are big when we don't know what something is. But after all, this is the element right above hydrogen in the periodic table: sodium.
Magnesium: Mg
It is the ninth most abundant element in the Earth’s crust. Magnesium’s most common compounds are oxides and hydroxides of magnesium ion Mg(OH)2, such as magnesite MgCO3 and brucite (Mg(OH)2). The free element is not found in nature, but occurs in over 700 different minerals and can be produced synthetically by reacting magnesium salts with acids.
Calcium: Ca
Calcium is an element, with the symbol Ca and atomic number 20. It is a soft grey alkaline earth metal, highly reactive, and has historically been valued as a better conductor of electricity than sodium.
It has been used for plating steel in car engines and in calcium-oxide based lighters to provide lighting at convenience stores.
Calcium fires are cool compared to sodium ones because it is less reactive. You’d want calcium atoms running through your veins instead of sodium. Calcium gives you stronger bones, after all.
Carbon: C
Carbon. We’re made of carbon. Everybody knows that right?
But what you may not know is that carbon is an element. And what most people don’t know is that carbon isn’t just one element…it’s several.
How many, you ask? 103 more than you would have guessed. So sit back, grab a cowlick macaron, and let’s journey through the atomic world of carbon…
Nitrogen: N
It was first discovered by Daniel Rutherford in 1772. It is represented by the diatomic molecule N2 (one nitrogen atom bound to two hydrogen atoms, N(H2)2), by far the most common molecule in the Earth's atmosphere (78.1% by volume) and accounts for nearly 80% of the atmosphere of Mars.
The next three most common naturally occurring isotopes of nitrogen are 14N (99.6%), 15N (0.4%), and 16N (0.1%).
Selenium: Se
That is found in the Earth’s crust and is a member of group 16 on the periodic table. It has atomic number 34 and symbol Se. Selenium was discovered in 1817 by Jons Jakob Berzelius and it was named after the moon Selene.
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I hope random element generators help you to learn everything about periodic tables. Here are the other tools if you are interested.