6 Properties of Third Period Elements: Physical and Chemical Properties

Hi all. In the periodic table there are 118 elements. The elements are arranged in two lanes, namely vertical (upright) and horizontal (flat). Vertical lanes are called groups , while horizontal lanes are called periods . Here we will find out the physical properties of the chemical elements of the third period.

Well, there are a total of 18 groups consisting of 8 main groups (IA-VIIIA) and 8 transition groups (IB-VIIIB) and 7 periods.

In the period lane, the elements are arranged based on the increase in atomic number and the tendency of elemental properties. This can be seen from the third period.

The third period elements consist of: Na (Sodium), Mg (Magnesium), Al (Aluminum), Si (Silicon), P ( Phosphorus / Phosphorus), S ( Sulfur / Sulfur), Cl ( Chlorine / Chlorine), and Ar (Argon).

Let’s discuss !!

  1. Na Has the Largest Atomic Radius

In one period, the radius of the atom will get smaller right.

The increase in atomic number causes the increasing charge of the nucleus (protons) and the skin of the atom (electrons). This causes the attractive force between the nucleus of the atom (+) to electrons (-) in the atomic shells get stronger. As a result, the distance between the nucleus and the outer shell is getting closer or in other words there is a decrease in the radius of the atom.

  1. Mg, and P Ionization Energy is Greater Than the Element on the Right

In one period, the number of valence electrons increases (Na has 1 valence electron, whereas Ar has 8 valence electrons).

The more the number of valence electrons, the higher the effort required by an element to release 1 valence electron. In other words, from left to right the ionization energy of an element is getting greater.

However, this does not apply to the elements Mg and P. Mg ionization energy is greater than Al, and P ionization energy is greater than S.

The deviation is due to the Mg atom having a more stable electron configuration because it meets the duplet rule. Pay attention to the electron configuration below.

Al is easier to release 1 valence electon, so Mg ionization energy> Al ionization energy .

Likewise with P atoms which have half-full 3p orbitals. According to Friedrich Hund (1896-1997), a physicist from Germany, the state of electrons scattered one by one in the p orbitals, is more stable when compared to the p orbitals there are already paired electrons.

Therefore, the P atom is relatively stable so it is more difficult to release electrons. As a result, Ionization Energy P> Ionization Energy S.

In full, the first ionisation energy of the third period element can be seen in the following graph.

  1. Greater Electronegativity

As the atomic radius decreases and the atomic number increases, electronegativity will increase. In one period, from left to right, the price of electronegativity is getting bigger. (Also read the  Difference between Valence and Oxidation Numbers )

  1. The Highest Melting Point and Melting Point Si

Si or Silicon has a boiling point price of 3,280 ° C and a melting point of 1,410 ° C. The amount of the boiling point and the melting point Si is caused by the structure of the substance of an element in the free state.

In the free state, Si takes the form of crystalline solids that bind covalently. Each Si atom will bind with 4 other Si atoms. Because of this type of bonding and the number of atoms involved, a higher effort is needed to break the bonds so that the boiling point and the melting point are also high.

  1. The reduced nature of metals

In the third period, there were three types of elements in it, namely metal, semi-metal ( metalloid ), and nonmetal.

In the free state, Na, Mg, and Al are metal elements with a substance structure in the form of crystalline solids, metal luster, and can conduct electricity (conductors).

Conversely, P, S, Cl, and Ar are non-metallic elements. In nature, phosphorus / P and sulfur / S are found in the form of solids. Whereas Cl and Ar are in the form of gas. Non-metallic elements cannot conduct electricity (insulators).

The Si is included as a semi-metallic element ( metalloid ), which is an element located in a transitional area between metal and non-metals and has both properties.

So, in one period (from left to right), the nature of the metal decreases while the nonmetal nature increases. Well, the reduced nature of this metal also causes deterioration in the electrical conductivity of an element.

In summary, the following table describes the 5 characteristics of the third period elements.

  1. The Weakening of the Alkaline and the Stronger of the Acid

If the third period elements are reacted with H2O molecules, they will form acidic and basic compounds.

Third period elements + H2O → acids-bases

These acid and base compounds formed have different strengths. Sequentially, the strength of acid-base elements of the third period changes from a strong base, then amphoteric (can be acidic or basic) in aluminum, then weak acid to become strong acid in chlorine.

The following compounds are formed from the elements of the third period and their properties.

Argon does not react to form new compounds, because Ar is a stable element.

Well, that is the discussion of the 6 Characteristics of the Third Period Elements. Hopefully this article on the physical properties of chemical elements in the third period is useful for you guys, thank you.


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