Introduction
We use different chemical formulas like O2, H2O, H2SO4, CO2 etc. We know the chemical formula for Carbon Dioxide is CO2. But we never thought about why it is CO2 and not CO3 or CO. Why has it been written in some particular way with specific numbers only? The answer to our question is Valency.
In this article, we will know about valency, how to determine valency, and the valency chart.
What is the Valency of elements?
As we know, atoms have a maximum of 8 electrons in their outermost shell. But, not all atoms have complete 8 electrons in the outer shell, which makes them unstable.
In the process of becoming stable and completing their octant, they try to combine with other atoms or participate in chemical reactions in which they will gain or lose electrons to achieve stability. Atoms constantly struggle to reach a stable state.
The number of electrons gained or lost by an atom to complete its outermost shell is valency. In other words, the valency or valency of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. To understand more about the valency of elements with examples, you are advised to check valency charts.
Application
Valency helps to determine a chemical formula. It also helps in knowing how the atoms of the element will combine with atoms of other elements. It is also used to explain the covalent bond formation in the molecule.
How to find the Valency of an element?
As we know, valency is the number of electrons we need to gain or lose to complete the outer octant and become stable. So here the number of electrons in the outermost shell of an element will determine its valency.
If an element has 4 electrons in its outer shell, it either needs to gain 4 more electrons or lose these 4 electrons to become stable. If an atom donates some of its electrons then it is known as positive valency.
If an atom gains some electrons from another atom then it is known as negative valency. There are various methods available to find the valency of an element.
Methods of determining Valency of an element
There are different methods available to find out the valency of an element. They are as explained below:
Using the periodic table: Periodic tables are arranged in such a way that we can easily determine the valency of an element just by looking at it in the table. For example, column one elements have a valency of 1 and column eighteenth elements have a valency of 0 and are inert.
Octet rule: Octet means eight. According to this rule, the outermost shell of an element must have eight electrons. If the outermost shell of an element has one to four electrons, it is positive valency.
If the compound has four, five, six or seven electrons in its outermost shell, the valency is determined by subtracting electrons from eight.
Valency from the chemical formula: this method is based on the octet rule too. By observing the combining of an element, we can determine valency.
Valency Chart of first 50 elements
| ELEMENT | ATOMIC
NUMBER |
VALENCY |
| 1 | Hydrogen | 1 |
| 2 | Helium | 0 |
| 3 | Lithium | 1 |
| 4 | Beryllium | 2 |
| 5 | Boron | 3 |
| 6 | Carbon | 4 |
| 7 | Nitrogen | 3 |
| 8 | Oxygen | 2 |
| 9 | Fluorine | 1 |
| 10 | Neon | 0 |
| 11 | Sodium | 1 |
| 12 | Magnesium | 2 |
| 13 | Aluminum | 3 |
| 14 | Silicon | 4 |
| 15 | Phosphorus | 5 |
| 16 | Sulfur | 6 |
| 17 | Chlorine | 5 |
| 18 | Argon | 0 |
| 19 | Potassium | 1 |
| 20 | Calcium | 2 |
| 21 | Scandium | 3 |
| 22 | Titanium | 4 |
| 23 | Vanadium | 4 |
| 24 | Chromium | 6 |
| 25 | Manganese | 4 |
| 26 | Iron | 4 |
| 27 | Cobalt | 4 |
| 28 | Nickel | 4 |
| 29 | Copper | 2 |
| 30 | Zinc | 2 |
| 31 | Gallium | 3 |
| 32 | Germanium | 4 |
| 33 | Arsenic | 5 |
| 34 | Selenium | 6 |
| 35 | Bromine | 5 |
| 36 | Krypton | 8 |
| 37 | Rubidium | 1 |
| 38 | Strontium | 2 |
| 39 | Yttrium | 3 |
| 40 | Zirconium | 4 |
| 41 | Niobium | 2, 3, 5 |
| 42 | Molybdenum | 2, 3, 4, 5, 6 |
| 43 | Technetium | 4, 6, 7 |
| 44 | Ruthenium | 1, 2, 3, 4, 5, 6, 7, 8 |
| 45 | Rhodium | 7 |
| 46 | Palladium | 2 |
| 47 | Silver | 1 |
| 48 | Cadmium | 2 |
| 49 | Indium | 3 |
| 50 | Tin | 4 |
Conclusion
In this article, we have learned about valency, different methods to find the valency of an element and a valency chart of the first 50 elements. This will clear your basics and make you understand valency in a simple form.