How Do You Know if Ionic or Covalently Bonded

There are primarily 2 forms of bonding that an cantlet can participate in: Covalent and Ionic. Covalent bonding involves the sharing of electrons betwixt 2 or more atoms. Ionic bonds class when two or more ions come together and are held together by charge differences.

So how practise you lot know what kind of bond an atom will make? That is actually the like shooting fish in a barrel part. Metals and Non-Metals when combined make ionic compounds. Non-Metals when combined with other Non-Metals brand covalent compounds. So all yous demand to be able to do is figure out what elements are Metals and which are Non-Metals. For that information we can use the periodic table:

Tutorial - Covalent Bonding
© 2008 WGBH Educational Foundation. All Rights Reserved.

Covalent Bonds

Every bit nosotros mentioned before, the electrons in an atom are what is responsible for forming bonds. What nosotros did not discuss previously is which electrons in the atom are involved in bonding. The bonding electrons are called the VALENCE electrons and they are the electrons that are found in the outermost shell of the cantlet. In the periodic tabular array beneath, you can see diagrams of each element that shows how many valence electrons information technology possesses. Conveniently, the Group Number at the elevation of each cavalcade in the periodic tabular array too gives the number of valence electrons. For example, Boron (represented as B in the periodic table) is in Group 3A and has 3 valence electrons; Carbon (represented as C) is in Group 4A and has iv valence electrons.

One time you lot know how many valence electrons an atom has, you tin start to build molecules. There are a couple of rules to follow however as you build:

1. The Octet Rule: The atoms that participate in covalent bonding share electrons in a manner that enables them to larn a stable electron configuration, or full valence shell. This ways that they want to acquire the electronic configuration of the element of group 0 of their row. The Noble Gases are like the Michael Hashemite kingdom of jordan'due south of the Chemistry world and every i of them wants to "exist like Mike".
2. There are several exceptions to the octet rule however:
   • Hydrogen (H) merely requires ii electrons to have a full valence shell since it only needs to be like Helium (He).
   • Elements on the third Period (3rd row) of the periodic table and beneath can actually take more than 8 electrons around them. They accept extra space to allow for the extra electrons.

Now that you know the number of valence electrons and the rules you lot can starting time making molecules. For instance, looking at hydrogen nosotros know that it is in Group I and thus has 1 valence electron, if it bound itself to another hydrogen they could share the two electrons between them and both be "happy". See below.

If that aforementioned hydrogen bonded to Chlorine, the hydrogen would get the 2 electrons it needs to be complete and the chlorine which has vii valence electrons would get the one more to fulfil its octet. See in a higher place.

Now that yous tin form covalent compounds we need to get over how to proper noun these compounds. Nomenclature is the fancy style of saying the rules for naming.

Covalent Compound Nomenclature

1. The first element is named first, using the elements proper name:

SF₆ Sulfur Hexafluoride

2. Second chemical element is named using the suffix "-ide"

SF_half-dozen Sulfur Hexafluoride (Fluorine becomes Fluoride)

three. Prefixes are used to denote the number of atoms

Prefix	Number Indicated
mono-	1
di-	2
tri-	iii
tetra-	4
penta-	5
hexa-	half-dozen
hepta-	vii
octa-	8
nona-	9
deca-	ten

SF₆ Sulfur Hexafluoride (There are vi Fluorines so Hexa is used every bit the prefix)

4. "Mono" is not used to name the starting time element

SF_vi Sulfur Hexafluoride (Notation that in that location is merely one Sulfur only no Mono prefix)

Note: when the addition of the Greek prefix places two vowels adjacent to ane some other, the "a" (or the "o") at the end of the Greek prefix is usually dropped; e.1000., "nonaoxide" would be written as "nonoxide", and "monooxide" would be written as "monoxide". The "i" at the terminate of the prefixes "di-" and "tri-" are never dropped.

Ionic Bonding

Ionic bonds are formed by the combination of positive and negative ions; the combination of these ions form in numerical combinations that generate a neutral (zilch accuse) molecule.

So how do you know what kind of ion an element will form?

Once more, our answers can be establish using the periodic table:

Just as with the covalent compounds, each ion wishes to form an octet and exist like the nearest noble gas. Sometimes it is easier for the element to proceeds electron(s) (anions) to produce the octet and sometimes it is easier for the element to lose electron(due south) (cations). If you look at the periodic tabular array to a higher place you will note that the Group 1A, 2A and 3A elements all form positive ions or Cations. This is considering it is easier energetically for those elements to lose 1, 2, or three electrons than information technology would be for them to gain 5, 6 or 7 electrons. The proceeds or loss of an electron mostly requires free energy and in one case y'all exceed the proceeds or loss of three electrons the energy cost is but too high for most atoms to reach. Yous should besides notice that the elements on the right side of the periodic table (the non-metals) in Groups 5A, 6A and 7A all form negative ions or Anions for the same reason.

You can make up one's mind the charge that an chemical element volition form as an ion past looking at how far that element is from the nearest noble gas. For instance, elements in Group 2A are 2 columns away from the nearest noble gas and so losing 2 electrons will give them the noble gas number of electrons; Group 5A elements are 3 columns away from the nearest element of group 0 so add-on of three electrons will work best for them and so on.

Tutorial - Ionic Bonding
© 2008 WGBH Educational Foundation. All Rights Reserved.

Forming Ionic Compounds

Every bit was mentioned in a higher place, ions come together in compounds to form neutral (uncharged) molecules. This means that the positive and negative ions have to be counterbalanced so that their charges all add up to nothing:

In the examples to the right, the sodium is +i and the chloride is -1 so adding them together to class a neutral molecule (positive charges + negative charges = nada) just requires ane of each. NaCl

But in the case of calcium which forms a +2 ion and chlorine which forms a -1 ion, we need ii chlorines to balance the accuse of the i calcium. CaCl_two

Here are a few more general rules to follow when building and naming ionic molecules:

1. The number of ions in the chemical compound is indicated as a subscript after the element's symbol: MgF₂ (Magnesium Fluoride), AlCl_three (Aluminum Chloride), or Al₂O_three (Aluminum Oxide)
2. The cation is generally listed first in the chemical compound: MgF₂ (Magnesium Fluoride), AlCl_iii (Aluminum Chloride), or Al_twoO_three (Aluminum Oxide)
3. The name of the compound is simply the name of the positive chemical element followed past the name of the negative element adding the �ide suffix: MgF_two (Magnesium Fluoride), AlCl₃ (Aluminum Chloride), or Al₂O_iii (Aluminum Oxide)

Notice that in ionic classification you do non employ the Greek prefixes to indicate the number of atoms in the molecule. This is because as chemists we know the number since the charge the ions accept on is anticipated.

So to sum upwards the process for identifying, writing and naming compounds:

Upward until now we have not discussed the metals beyond those in the Groups IA, 2A and 3A. The metals in the B Groups in the middle of the periodic tabular array are besides involved in ionic bonding. Their charges as an ion are less predictable however and they tin actually have more than one charge as an ion:

Whenever yous write an ionic compound that contains a transition element ion, y'all have to indicate in the name which ion you are using by the inclusion of a Roman numeral in the proper name:

Feⁱⁱ⁺ + Br^- → FeBr_two   Iron (II) Bromide

Feⁱⁱⁱ⁺ + Br^- → FeBr_iii   Atomic number 26 (III) Bromide

Polyatomic Ions

Another special instance for creating and naming compounds derives from the beingness of polyatomic ions. Polyatomic ions are ions that are made up of not-metals that when combined form a charged molecule. A table of the more common of these ions is shown below:

Common Polyatomic Ions

When a polyatomic ion is office of an ionic chemical compound the rules for assembly are the same: the ions must combine to brand a neutral molecule. Simply considering the polyatomic ion must be treated like a unmarried substance parenthesis are placed around it in the formula if more than one ion is required.

For instance, if you combined Magnesium Ion, Mg²⁺ and Phosphate Ion, PO₄ ^3-, to rest the charges you would need iii magnesium ions and 2 phosphate ions: Mg_three(PO₄)₂ The parenthesis are placed around the polyatomic ion to indicate that the subscript creates a multiple of the entire ion not simply a single cantlet. The parentheses are only used in cases where there is more than than one polyatomic ion in the molecule. So for instance, MgSO₄ contains the sulfate ion (SO₄ ^two-) just since only 1 is required to balance the molecule, no parentheses are needed.

Let's Practice:

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Source: https://www.chem.fsu.edu/chemlab/chm1020c/lecture%204/01.php

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