Problem 1 - Chemistry for Allied Health

Question

What is a free element, and what is the oxidation number for atoms that exist as a free element?

Step-by-Step Solution

Answer

A free element is a pure element with an oxidation number of 0.

Step 1: Understanding Free Elements

A free element is a chemical element that is not combined with other elements. This means it exists in its pure form, such as individual atoms or molecules, like O2 for oxygen or Fe for iron.

Step 2: Identifying Oxidation Number

The oxidation number for atoms in their elemental form is always 0. This is because they are not bonded to any other elements that would require a loss or gain of electrons.

Key Concepts

Oxidation Number

The oxidation number is an important concept in chemistry that indicates the degree of oxidation of an atom in a chemical compound. It essentially tells us how many electrons an atom gains or loses when forming compounds. This concept helps chemists understand the transfer of electrons in oxidation-reduction (redox) reactions.
When atoms are in their elemental state, their oxidation number is always zero. This occurs because these atoms are not bonded to any other atom, meaning there is no need for them to lose or gain electrons.

• For example, the oxidation number of an oxygen atom in O sub 2 is 0.
• Similarly, an iron atom in its elemental state (Fe) also has an oxidation number of 0.

Understanding oxidation numbers not only helps predict the outcome of chemical reactions but is also pivotal in determining the electron flow within those reactions.

Elemental Form

When we say an element is in its elemental form, we are referring to its pure state, where it is not combined with any other types of atoms. This is often how many elements naturally occur in the Earth's crust or atmosphere. They exist as a single type of atom or as simple molecules consisting of just one type of atom.
Common examples include:

• Helium (He) - existing as single atoms
• Oxygen (O sub 2) - existing as diatomic molecules
• Sulfur (S sub 8) - existing as polyatomic molecules

The elemental form is significant because it represents the simplest form in which an element can exist in nature. This form is crucial in calculating and understanding various chemical reactions and processes. In general, elements in their elemental form exhibit traits specific to their grouping in the periodic table, such as reactivity and atomic size.

Chemical Element

Chemical elements are fundamental substances that cannot be broken down into simpler substances by ordinary chemical means. Each element is made up of atoms, which are the building blocks of matter. Every chemical element, such as hydrogen (H), carbon (C), or gold (Au), is defined by the number of protons in its nucleus, also known as its atomic number.
There are currently 118 recognized chemical elements, of which around 94 occur naturally on Earth. These elements combine in various ways to create all known matter in the universe.

• Each element is distinct in its own chemical and physical properties.
• Elements are arranged in the periodic table based on their atomic number.

Understanding chemical elements is fundamental in the study of chemistry because they are the basic building blocks that make up chemical substances and participate in chemical reactions.