Main Group Elements

Core Concepts

In this tutorial you will be introduced to the main group elements in chemistry and physics, and why they are considered the main group elements.

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What are the “Main Group Elements”

The main group elements, also known as the representative elements, consist of elements belonging to the s-block and p-block of the periodic table and are most abundant on earth and space. Many elements in the main group are necessary to life on earth, specifically oxygen, carbon, nitrogen, and hydrogen.

Orbital Blocks on the Periodic Table

Elements that are in similar groups or columns can be placed together into blocks on the periodic table based on their valence electrons (their outermost electrons). There are four blocks on the periodic table s, p, d, and f., If elements are in the same block their last valence electron occupies the same orbital. The periodic table arranges elements according to their electron configuration.

S-Block

All elements in this block will occupy the same block. This means the atoms of these elements have their valence electrons in the s-orbital. Elements in this block are located in groups one and two, including helium.

With the exception of hydrogen and helium, all the elements in this block are metals and have similar properties.

S-Block Element Properties

S-block elements have one oxidation state
Their general valence electron configuration is ns^1-2
The alkali metals (group 1) have a +1 oxidation state and group 2 elements (alkaline Earth metals) have a +2 oxidation state.
All s-block elements are highly reactive, except helium.
They tend to be soft with low boiling points
S-block metals are highly electropositive.

P-Block

This block is on the right side of the periodic table and contains elements ranging in six different columns. These elements’ valence electrons are in the p orbital. Helium is excluded from the p-block, which starts at column 3A and ends at column 8A.

The properties of these elements will vary because they span over a large portion of the periodic table of elements.

P-Block Element Properties

The p-block elements have multiple oxidation states. For example, sulfur has -2, 0, +2, +4, and +6.
The oxidation state depends on the group. Group 17 elements (halogens) have a -1 oxidation state but the group 18 (noble gases) has an oxidation state of 0.
The general oxidation state is ns² np^1–6 . Their valence electron is in the p-orbital
They contain metals, nonmetals, and metalloids so their properties depend on their group.

Importance of Main Group Elements

The main group elements are important for a few reasons,

Earth and the Universe

The main group elements are most abundant in making up the earth and the universe. These elements make up 80% of Earth’s crust. Oxygen and silicon make up a majority of the Earth’s crust. Like, oxygen and silicon, hydrogen and helium make up a majority of the universe. Hydrogen, which is said to have been created during the hot Big Bang, makes up almost 70% of the universe. Carbon is an essential element for all forms of life on Earth.

Industrial

These main group elements and their compound are among the most economically important elements. The element lithium is a key factor in treating diseases like schizophrenia and bipolar disorder. The most common use for the element sodium (Na) is to season our food, in the form of table salt or sodium chloride (NaCl). Atomic clocks use cesium because it can measure resonance frequencies accurately.

Biological Uses

Magnesium is one of the most abundant alkaline earth metals. It is very useful in medical settings. Magnesium is used in antacids, laxatives, and Epson salts. Calcium is even more abundant on Earth than magnesium. It is a key component in the structures of living things like bones, teeth, shells, and exoskeletons. Unlike beryllium, a very transparent element, X-Rays can not penetrate barium so it is used to see the GI tract.

What about the D-Block Elements?

For the most part elements in the d-block have not been considered to be in the main group of elements on the periodic table. The transition metals in the middle of the periodic table, the lanthanides, and the actinides below the main body of the periodic table do not categorize as main group elements. Some scientists will not consider hydrogen as a main group element.