If two or more elements mix chemically in a defined mass ratio, the effect is known as a compound. Compounds are compounds made up of two or three distinct kinds of elements in a fixed proportion of atoms. As elements merge, any of the elements’ individual properties are destroyed, and the newly created compound has new properties. 

Chemical Formula: Chemical formulas are used to describe compounds. A chemical formula is a description of the atom quantities that make up a certain chemical compound. 

The chemical formula of water is H2O, indicating that two hydrogen atoms and one oxygen atom have joined to create one molecule of H2O. The molecular formula for popular salt is NaCl, which indicates that one molecule of NaCl is made up of one atom of sodium and one atom of chlorine.

There are two forms of compounds—molecular compounds and salts. Covalent bonds are used to tie atoms together in molecular compounds. It is bound together in salts by ionic bonds. These are the two kinds of bonds that a compound contains.

Elements may be described as a collection of atoms with the same number of protons in their atomic nuclei. While the atoms of an element contain the same number of protons, they may have varying amounts of neutrons, and hence different weights. 

Isotopes are atoms of the same element that have differing amounts of neutrons. There are currently 118 components, with the first 94 being naturally occurring and the other 24 being synthetic. 

Elements are chemical compounds that correspond to a particular spot on the current periodic table. Elements are made up of just one form of an atom. They can live as atoms or molecules and cannot be broken down into smaller pieces. The International Union of Pure and Applied Chemistry (IUPAC) assigns symbols to elements. For example, the letters O and Al stand for oxygen and aluminium, respectively.

The elements are grouped in the periodic table and categorised as metallic or non-metallic based on their classes. Metals are grouped into three categories: core group metals, transition metals, and f-block metals. These are further subdivided based on their characteristics.

The resultant compound is known as a ‘Mixture’ in chemistry when two or more compounds combine without undergoing a chemical alteration. 

The product of combining compounds does not compromise its identity, and they are not chemically mixed. Chemical substances such as atoms and chemicals are mechanically blended or mixed to produce mixtures.

Below are some of the more important techniques for distinguishing substances or mixtures: 

• Handpicking
  This approach entails manually sorting out all of the undesirable compounds and extracting them from the useful ones. One of the separated substances may be an impurity that needs to be discarded or that both separated substances are useful.
• Threshing
  This process is most often used during crop harvesting. Wheat stalks are typically dried after they are harvested. By pounding the dry stalks to shake off the dried seeds, the grain is removed from the stalks and ground onto the earth.
• Sieving
  It is used to isolate mixtures of often different-sized ingredients. The mixture is filtered into the sieve’s pores. All of the smaller compounds move through quickly, but the mixture’s larger elements remain kept.
• Evaporation
  Evaporation is a method for extracting a mixture, typically a liquid and a soluble solid solution. The solution is heated until the organic solvent evaporates, converting into a gas and largely leaving the firm residue behind.
• Distillation
  Distillation is used where a combination comprises two or more pure liquids. A liquid mixture’s components are vaporised, diluted, and then separated here. As the mixture is heated, the volatile portion vaporises first. The vapour is deposited in a liquid condition by going through a condenser.

Isolating, sorting, and purifying chemical substances is one of the most essential and time-consuming activities in chemistry. Some important and relevant techniques of separation are:

• Extraction 
• Distillation 
• Chromatography

In this chapter, we learned about the basics of elements, compounds and mixtures. We learned about the separation techniques and their types.

1. What are the most important characteristics of mixtures?
   A mixture’s individual components maintain their initial physical and chemical properties. Separating the individual components of a mixture is often normally easy. Finally, the components’ proportions vary in the mixture.
2. Give an example of a mixture.
   Soil, saline solution, certain alloys, and bitumen are all made from homogeneous mixtures. Heterogeneous mixtures include sand, oil and water, and chicken noodle soup.
   
3. Is a pure material called an element?
   An element is a common material that cannot be separated into separate forms. Compounds such as carbon, oxygen, hydrogen, silver, and iron are examples of elements. Each element is made up of just one atom type.
   
4. What is the distinction between an atom element compound and a mixture?
   A single molecule has the same number of protons and electrons, and most atoms have at least as many neutrons as protons. An ingredient is a substance made entirely of one kind of atom. A composite is a substance made up of two or more chemically related components.
   
5. What is a compound example?
   A compound is a substance made up of two or more separate substances. Compounds include things like water, carbon dioxide, and table salt.