Elements , Compounds and Mixtures

Chemistry / Matter and its Composition

Matter : 
Anything that has weight and occupies space and can be perceived by our senses is called matter.
States of matter: 
Solids: A solid has a definite shape and volume. Examples of solids include ice (solid water), a bar of steel, and dry ice (solid carbon dioxide).
Liquids: A liquid has a definite volume, but takes the shape of its container. Examples of liquids include water and oil.
Gases: A gas has neither a definite volume nor a definite shape. Examples of gases are air, oxygen, and helium.
Plasma is recognized as fourth state of matter.

Inter conversion of three states of matter:
1. Melting : Change of substance from solid state to liquid state.
2. Evaporation or boiling: Change of substance from liquid state to gaseous state. Transpiration is the evaporation of water into the atmosphere from the leaves and stems of plants
3. Condensation : change of substance from gaseous state to liquid state.
4.Freezing or solidification : change of substance from liquid state to solid state.

 Sublimation:

There are some substances that directly   changes from solid state to the gaseous state and vice versa without passing through the liquid state. This process is called sublimation and the substances are called sublimable substances or sublimate. 

Example: Camphor, ammonium chloride, iodine naphthalene etc.

 Melting Point:

The fixed temperature at which a solid changes into a liquid at atmospheric pressure is called its melting point.

The temperature remains constant till whole of the solid changes into liquid. The melting point of ice is 0◦C.

Boiling Point:

The fixed temperature at which a liquid state changes into a gaseous state at atmospheric pressure is called its boiling point.

The temperature remains constant till whole of the liquid changes into vapour state. The boiling point of pure water is 100◦C.

Condensation Point:

The fixed temperature at which a gas starts changing into a liquid state is called its condensation point.

The condensation point of steam is 100◦C.

Freezing point:

The temperature at which liquid starts changing into its solid state is called its freezing point.

Pure water freezes at 0◦C under normal conditions.  

l Properties of Solids, Liquids and Gases →

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Element Definition:

Elements – Elements constitute the simplest chemical substances in which all the atoms are exactly the same.

Compound Definition:

Compounds – Compounds are chemical substances made up of two or more elements that are chemically bound together in a fixed ratio.

Chemistry is the study of the structures, physical properties, and chemical properties of material substances. It is very important to understand that all gases, liquids, and solids are not the same. All are different in terms of their composition. This is the reason why the classification of the matter is very important.

Classification of Matter

1. Elements
2. Compounds
3. Mixtures

Here we are going to discuss two categories of the matter: Elements and Compounds

What is a Compound?

When two or more elements chemically combine in a fixed ratio by mass, the obtained product is known as a compound. Compounds can be defined as substances consisting of 2 or more different types of elements in a fixed ratio of its atoms. When the elements combine, some of the individual property of the elements is lost and the newly formed compound has new properties.

Chemical Formula: Compounds are represented by their chemical formula. A chemical formula is a symbolic representation of the proportions of atoms that constitute a particular chemical compound.

The chemical formula of water is H₂O

 which shows two atoms of hydrogen and one atom of oxygen have combined to form one molecule of  H₂O.

 The chemical formula for common salt is NaCl which shows one atom of sodium and one atom of chlorine combine to form one molecule of NaCl.

1. Types Of Compounds

Compounds can be classified into two types, molecular compounds, and Salts. In molecular compounds, atom binds each other through covalent bonds. In salts, it is held together with ionic bonds. These are the two types of bonds out of which every compound is made of.

2. Example Of Compounds

• Example of compounds includes water ( H₂O) , Hydrogen Peroxide (H₂O₂ )etc. You could see water’s chemical formula, it says it has 2 atoms of Hydrogen combined with 1 atom of oxygen and in hydrogen peroxide, it has 2 atoms of hydrogen and two atoms of oxygen.

• Similarly,  an example of salt would be the table salt (NaCl) which has 1 atom of sodium and one atom of chlorine.

What are the Elements?

We can define elements as a species of atoms that have the same number of protons in their atomic nuclei. Although an element’s atoms have the same number of protons, they can have different numbers of neutrons and hence different masses.

Isotopes: When atoms of the same element have different numbers of neutrons, they are known as isotopes. As of now, there are 118 elements, of which the first 94 are naturally occurring while the remaining 24 are synthetic elements.

Elements are complete chemical substances which relate to a single entry in the modern periodic table. Elements consist of one kind of atoms only. They cannot be broken down into simpler fragments and can exist as atoms or as molecules. Elements are represented by symbols that are assigned by IUPAC. For example, Oxygen is represented by O, Aluminium is represented by Al, etc.

1. Types of Elements:

The elements are arranged in the periodic table and are split depending upon their groups as either metallic or non-metallic. Metallic is further classified into Main Group Metals, Transition Metals, and f-block metals. These are again further divided depending upon their properties.
2. Examples of Elements:

Elements exist in their simplest form and cannot be broken down further. So, elements can exist in the form of ions, atoms, isotopes, molecules.

• An example of an element is Nitrogen atom(N), Nitrogen gas (N₂), Nitrogen ion(N^3-) and Nitrogen isotopes (Nitrogen-13, Nitrogen-14, and Nitrogen-15).

Similarly, you could see other elements’ existence.

Name of the element	Chemical symbol
Hydrogen	(H)
Boron	(B)
Carbon	(C)
Silicon	(Si)
Sodium	(Na)
Lead	(Pb)
Platinum	(Pt)

Mixtures:

In chemistry, a mixture is a material made up of two or more different substances which are physically combined. 

A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions,suspensions and colloids.

Characteristics of mixtures:

Mixtures can be either homogeneous or heterogeneous. 

A mixture in which its constituents are distributed uniformly is called homogeneous mixture, such as salt in water.

 A mixture in which its constituents are not distributed uniformly is called heterogeneous mixture, such as sand in water.

One example of a mixture is air. Air is a homogeneous mixture of the gaseous substances nitrogen, oxygen, and smaller amounts of other substances. 

Salt, sugar, and many other substances dissolve in water to form homogeneous mixtures. 

A homogeneous mixture in which there is both a solute and solvent present is also a solution. Mixtures can have any amounts of ingredients.

Mixtures are unlike chemical compounds, because:

• ·         The substances in a mixture can be separated using physical methods such as filtration, freezing, and distillation.·         There is little or no energy change when a mixture forms.·         Mixtures have variable compositions, while compounds have a fixed, definite formula.·         When mixed, individual substances keep their properties in a mixture, while if they form a compound their properties can change.

Mixtures are one product of mechanically blending or mixing chemical substances such as elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup.

Despite the fact that there are no chemical changes to its constituents, the physical properties of a mixture, such as its melting point, may differ from those of the components. 

Some mixtures can be separated into their components by using physical (mechanical or thermal) means. 

Azeotropes are one kind of mixture that usually poses considerable difficulties regarding the separation processes required to obtain their constituents (physical or chemical processes or, even a blend of them).