Question Video: Connecting the Group Number with the Charge of an Ion | Nagwa Question Video: Connecting the Group Number with the Charge of an Ion | Nagwa

Question Video: Connecting the Group Number with the Charge of an Ion Chemistry • Second Year of Secondary School

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Sulfur is in group 16. What is the charge of the sulfide anion?

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Video Transcript

Sulfur is in group 16. What is the charge of the sulfide anion?

A group is a collection of elements with similar chemical or electronic properties. The periodic table is organized in such a way that elements with similar chemical or electronic properties are found in the same column. Thus, each column of the periodic table represents a different group.

Elements of the same group tend to have similar chemical or electronic properties because atoms of these elements typically have the same number of valence or outermost electrons. For many elements, we can determine the number of valence electrons in a neutral atom in its ground state by using the arrangement of the periodic table. We simply number the columns of the periodic table from left to right, skipping the d-block elements. So atoms of elements in group 14 should have four valence electrons in their ground state.

In the question, we are told that sulfur is in group 16, so an atom of sulfur should have six valence electrons in its ground state. We can draw a diagram like this to represent the six valence electrons in a sulfur atom. But the question asked us about a sulfide anion, not a sulfur atom.

A sulfide anion is a negatively charged ion of sulfur. So we already know that the charge of the sulfide anion will be negative. But in order to determine the magnitude of the charge, we must consider how a neutral atom might react to become a sulfide anion. We can use the octet rule to help us. The octet rule is a rule of thumb which states that atoms tend to gain, lose, or share electrons in order to have eight valence electrons.

A neutral sulfur atom in its ground state has six valence electrons. This atom would need to gain two additional electrons in order to have eight valence electrons. By gaining two electrons in its outer electron shell, the sulfur atom becomes the sulfide anion. But what is the charge of this ion? A sulfur atom is neutral and has no charge. But in becoming the sulfide anion, the neutral atom gained two negatively charged electrons. This means that the sulfide anion must have a charge of two minus. So we have used the information that sulfur is in group 16 to determine that the charge of the sulfide anion is two minus.

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