What type of change occurs at the molecular level?

Answer 1

We have already seen that chemical reactions are changes in matter and that they happen everywhere. If you look a little closer and observe your surroundings, you will notice that many of the substances around you are changing. Are all of these changes chemical reactions?

No. You know that sometimes chemical changes take place and sometimes physical changes take place. For this reason it is said that

A physical change is a change in the properties of a substance that does not change.

A change of state is a physical change.

A chemical change is a change in the properties of a substance.

Combustion is a chemical change

You can memorize these definitions, but do you know what we mean by "properties of matter"? When does it change and when does it not? If you can't answer these questions, you don't know how to distinguish between physical and chemical changes.

Remember everything you know about the composition of matter, about elements and compounds, about pure substances and mixtures. When we talk about the properties of a substance, we describe its composition and structure, just as we describe what elements it is made of and in what proportions. Regardless of whether it is a single pure substance or a mixture of several substances. You already know that a pure substance is one whose composition is fixed because all the particles are the same, and can be expressed by a formula, such as H 2Or, the chemical formula for water, or NaCl, the chemical formula for sodium chloride, a table salt.

When one or more of these pure substances "disappear" in a substance transformation, a chemical change or chemical reaction takes place. But as you know, substances do not disappear (Lavoisier's law). So, from the original atoms that "disappear", one or more new pure substances "emerge". If during the transformation no matter "appears" or "disappears", then a physical change has taken place.

Answer 2

At the molecular level, changes can involve chemical reactions where bonds are broken and formed to create new molecules, or changes in the structure of molecules such as alterations in their conformation or arrangement. These changes can affect the properties and functions of biological molecules like proteins or DNA.

Answer 3

if it didnt the atom would explode causing a nuclear meltdown

Answer 4

After each cell division chromossomes get shorter.

Years of exposure to reactive atoms and molecules also take a toll. Collagen starts to wear down and wrinkles appear.