AlH4- Lewis Structure & Characteristics: 11 Complete Facts

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The valence electrons prediction of atoms or elements in the form of lines and dots is known as Lewis structure. Let us have a brief discussion on AlH4– lewis structure.

AlH4– lewis structure includes metal and non-metallic elements.  It is composed of one aluminum metal and four hydrogen atoms. The electronegativity of the Al atom is less than the H atom, though the Al atom occupies a central position. All the 4 H atoms are surrounded by it with an ionic bond.

AlH4– is the chemical formula for Alumanuide and an ionic compound. AlH4– ion gains 1 electron do creates a -1 charge on it. AlH4– lewis structure is placed in a square bracket as it has a negative charge. Let us discuss more briefly valence electrons, lone pair, the octet rule, formal charge, and more characteristics of AlH4– lewis structure and some facts of it.

 How to draw AlH4– lewis structure?

To draw a lewis structure there are some steps and rules to follow which are given below.

Valence electrons of AlH4– and bonding of it:

Evaluate the valence electrons present in the AlH4– lewis structure by adding all the valence electrons of Al and H atoms. Arrange the electrons to make bonding between Al and H atoms.

Lone pairs and Octet rule application on AlH4–:

As the bonding form between all the Al and H atoms of AlH4– remaining unshared electrons are considered as lone pair electrons, mark them. Apply the octet rule to check whether the Al and H atoms have complete or incomplete octets.

The formal charge on AlH4– and recognize its shape:

Use the particularly given formula of formal charge to calculate the AlH4– formal charge. Thereafter, recognize the shape, bond angle, and hybridization of the AlH4– lewis structure.

AlH4 1
AlH4- lewis structure

AlH4– valence electrons

The outermost valence electrons present in the outermost shell or orbital of an atom are called valence electrons. Let us discuss AlH4– lewis structure valence electrons.

AlH4– lewis structure contains a total of 8 valence electrons in it. The Al metal comes under the 13th group of the periodic table and thus it has 3 valence electrons in its outermost shell. The H atom comes under the 1st group of the periodic table and has 1 valence electron in its outermost shell.

Below are the steps given to calculate the AlH4– lewis structure valence electrons.

  • Aluminium metal has valence electrons = 3 x 1 (Al) = 3
  • Hydrogen atoms has valence electrons = 1 x 4 (H) = 4
  • Add extra one electron due to minus (-) charge on AlH4– = 01
  • Total valence electrons on AlH4– lewis structure = 3 + 4 + 1 = 8
  • Total electron pairs on AlH4– are identified by dividing its valence electrons by 2 = 8 /2 = 4.
  • Hence, AlH4– lewis structure has 8 valence electrons and 4 electron pairs.

AlH4– lewis structure lone pairs

The non – bonding electrons of an atom or molecule are on pairing called the lone pair electrons. Take a brief look at the AlH4– lewis structure lone pair electrons.

AlH4– lewis structure contains total zero lone pair electrons. It contains 08 valence electrons in AlH4– molecule. All the 8 electrons are being bond pairs forming 4 ionic bonds with central Al and outer 4 H atoms. Thus, no unshared electrons get remain placed anywhere in AlH4–.

AlH4– lewis structure octet rule

The availability of 8 electrons in the outer orbit of an atom is considered a stable atom describes in the octet rule. Let us discuss the application of the octet rule on AlH4– ion.

AlH4– has a complete octet of central Al atom. The 4 H atoms have 2 electrons, which satisfies their valency. All 4 h atoms have incomplete octets due to the presence of only 2 electrons. All the 8 valence electrons get surrounded around the Al atom. So, it has a complete octet due to 8 electrons on it.

AlH4– lewis structure formal charge

The formal charge is the positive or negative charge on the atoms that occurs due to the loss and gain of its electrons. Below is the brief discussion on the AlH4– formal charge.

Formal charge of AlH4– lewis structure is = (valence electrons – non-bonding electrons – ½ bonding electrons)

The calculative part of the AlH4– lewis structure is explained in the below-given table.

Atoms of AlH4–
lewis structure		 Valence
electrons on
Al, and H		 Non – bonding
electrons on
Al, and H		 Bonding
electrons on
Al, and H		 The formal
charge on
Al, and H
Central Aluminium
(Al) atoms		 03 00 08 ( 3 – 0 – 8 / 2 )
= – 1
Four Hydrogen
(H) atoms		 01 00 02 ( 1 – 0 – 2 / 2 )
= 0
AlH4- lewis structure formal charge, Al = – 1, H = 0

AlH4– lewis structure shape

The arrangements of atoms or elements of a molecule in a definite manner are called the shape of that molecule. Let us discuss AlH4– lewis structure shape.

AlH4– lewis structure contains tetrahedral shape and geometry. The central Al atom is surrounded by outer 4 bonded H atoms and has no lone pairs on it. All Al and H atoms get bonded with an ionic bond. Thus it has an AX4 generic formula as per the VSEPR theory module of molecular structures.

AlH4– hybridization

The overlapping of .atomic orbitals of an atom can produce a new hybrid orbital of similar energy is called hybridization. Take a brief look at AlH4– ion hybridization.

AlH4– lewis structure has sp3 hybridized central aluminum atom. The steric number for the central Al atom of AlH4– is 4. The steric number of Al atom is calculated as = total bonds on Al + lone pair electrons on Al atom. Therefore, it has 4 + 0 = 4 steric number.

So, in accord with the VSEPR module Al atom of AlH4– has sp3 hybridization. In AlH4– ion, it has overlapping or mixing of one ‘s’ and 3 ‘p’ atomic orbitals of central Al atom to form a new sp3 hybrid orbital having equal energy same as old orbitals.

AlH4– lewis structure angle

The gap or angle within all the alternate bonds of any molecule is called the bond angle of that molecule. Let us take a brief look at the explanation of the AlH4– ion bond angle.

The AlH4– ion has a 109.50 bond angle within its structure. The central Al atom of AlH4– ion is connected with 4 H atoms forming tetrahedral geometry. So, the VSEPR theory says species like AlH4– have an AX4 generic formula and have tetrahedral geometry. So, it has an H – Al – H bond angle of 109.50.

Is AlH4– polar or non – polar?

The electron sharing and electronegativities of atoms show their polarity due to the creation of dipoles on them. Below is a discussion on whether is AlH4– polar or non–polar.

AlH4– ion is non – polar in nature. As per the VSEPR theory, the molecules like AlH4– ion having a central atom with no lone pair and having 4 bonded atoms having tetrahedral geometry are non-polar compounds. The electronegativity difference between Al and H atoms is 0.5 which confirms it is non–polar.

Why AlH4– is non – polar?

AlH4– is a non – polar ion because the central Al atom is attached to the same molecules. All H atoms do not have any lone pairs. Overall electron density is acquired on the central Al atom only. It has no partial charge formation on Al and H atoms and its dipoles cancel each other and have zero dipoles.

Is AlH4–an electrolyte?

Electrolytes are compounds that get ionized on added to water and are able to conduct electricity. Let us discuss some details about whether AlH4– is an electrolyte or not.

AlH4– is not an electrolyte. It is just an anion containing a negative charge. It cannot be further ionized as positive or negative ions on added to water. AlH4– on added to water produces aluminum hydroxide. AlH4- anion is only forming a compound by combining with other positive charge cations.

Thus, AlH4– can behave like an electrolyte only on forming molecular compounds. Thus, AlH4– alone cannot conduct electricity and are not an electrolyte.

AlH4– + 4 H2O → Al(OH)3 + OH– + 4 H2

Is AlH4–ionic or covalent?

The electrostatic force of attraction shows ionic character and covalent bonds show covalent character. Take a look at the discussion of whether AlH4– is ionic or covalent.

AlH4– is an ionic compound. It is an anion due to the presence of a negative charge on it. AlH4 molecule has 7 valence electrons and is in need of one electron. It gains one electron from other compounds due to which it has a negative charge. It has no covalent bond in AlH4– and no covalent moiety.

Why AlH4– is ionic?

AlH4– is ionic in nature because all the atoms in it are attached to an ionic bond. All the Al and H atoms are held together due to the strong electrostatic force of attraction between them and form a strong ionic bond. It comprises an (Al) metal and an (H) non-metal element which confirms its ionic character.

Conclusion:

AlH4– lewis structure contains 8 valence electrons and zero lone pair electrons. It has a complete octet of central Al atoms. The formal charge on Al atoms is -1 and on H atoms are zero. It has a tetrahedral shape and geometry with sp3 hybridization and a 109.5-degree bond angle. It is ionic, non – polar, and non – electrolytic

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