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An element is a pure substance or the species of atoms having the same number of protons in their atomic nuclei. It is composed of only single types of atoms and cannot be broken down into simpler substances. It can exist in the form of ions, atoms, isotopes, molecules. All the elements are arranged in the periodic table depending upon their physical and chemical properties. The number of protons present in the atomic nuclei of an element is referred to as its atomic number. Elements are found in nature both in combined form and individual form. Nitrogen, oxygen, and argon are some of the elements which are found in the mixture of air.
| Table of Content |
Keyterms: Element, Proton, Nuclei, atoms, isotopes, molecules, air, Nitrogen, oxygen, argon, atomic number
Read More: Reverberatory Furnace
What Are Elements?
The element can be defined as a type of atom which cannot be broken down into simpler molecules and made up of the same type of atom. Atoms are the smallest and indivisible particles. The atomic nucleus of an atom consists of electron, proton and neutron in which proton denotes the atomic number of elements. There are about 118 elements in the periodic table and each one has specified a place in the periodic table on the basis of their atomic number and properties.
Atomic number is the number of protons present inside the nucleus of an atom whereas the number of protons and nucleus within the nucleus is known as mass number. Any element having the same mass number but differs in neutrons is called an isotope.
This figure shows the evolution of atomic models over the years:
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Geochemical Classifications of Elements
The elements are divided into several categories. The classification of the elements was given by a scientist V. M. Goldschmidt and it depends upon the affinity of those elements such as to form different types of compounds. The elements are distributed among the Earth’s major geochemical parts like crust, mantle core, hydrosphere and atmosphere. Going more in detail they were divided into four groups
- Lithophiles: Elements which are found in the rock structure, or in the mantle or crust of earth come under this category. Mg, Mn, Ti, Na, Ca, K, U, Th, Si, and Fe are some of the examples of lithophiles.
- Chalcophile: Elements which form disulfide bonds and are highly insoluble sulfides as well as have low affinity of oxygen. Example: Pb, Zn, Cd, Mo Cu, Hg, Sb, Sn, Tl, Te, As and much more.
- Siderophile: Iron loving elements found in the metallic core of earth in the form of alloy. Pt, Pd, Ir, Ru, Rh, and Os are some of the elements.
- Atmophile: Volatile compounds exist at exceptionally low temperatures such as H, C, N, He, Ne, Ar, Kr, Xe, Rn.
This periodic table shows the geochemical classification of the elements.
Characteristics Of An Element
The three main characteristics of an element are given below:
- Atoms of an element can neither be destroyed nor be created in a chemical reaction such as phosphorus (P4) or sulphur (S8) molecules cannot be broken into simpler substances.
- Each of the elements in a periodic table is represented by a unique symbol.
- All the elements are classified in three categories: metals, nonmetals and metalloids.
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| Important Topics | ||
|---|---|---|
| Clemmensen Reduction Reaction | Williamson Ether Synthesis | Tollen’s Test |
| Ruthenium | Rubidium | Lutetium |
| Periodic Acid Formula | Technetium | Strontium |
| Seaborgium | Rutherfordium | Scandium |
Things to Remember
- Elements exist in three different forms in nature: solid, liquid and gas which can be extracted from various sources such as earth, air, water etc.
- The study of extraction of elements from other metals is known as metallurgy.
- Metalloids are substances which have the property of both metals and nonmetals such as Silicon, Carbon.
- Alloy is the mixture of three or more types of elements.
- The Group 17 of the periodic table is called Halogen family and Group 18 is known as Noble gas having the stable electronic configuration.
Read More: Red Phosphorus
Important Questions
Ques 1. Which element is present in the 3rd period and 17th group of the periodic table? (1 mark)
Ans. The element located in the given group and period is Chlorine of atomic number 17.
Ques 2. Why do the same group of elements have similar physical and chemical properties? (2 marks)
Ans. The elements of the same group has similar physical and chemical properties due to presence of the same number of electrons in its outermost valence shell electronic configuration.
Ques 3. What do you mean by Atomic radius? (1 mark)
Ans. The distance between the atomic nuclei and the outermost shell of an electron in the atom of any element is called the atomic radius. This refers to both the metallic or covalent radius of metal and non metals.
Ques 4. How many elements are found in a periodic table? (1 mark)
Ans. There are 118 elements in the periodic table arranged on the basis of atomic number.
Ques 5. Write the electronic configuration of elements of s, p, d and f blocks? 9 (2 marks)
Ans. Below are given the electronic configuration of the blocks
- s-Block elements - ns 1-2 where n is between 2 – 7.
- p-Block elements - ns2 np1-6 where n is between 2-6.
- d-Block elements - (n – 1) d1-10 ns 0-2 where n is between 4-7.
- f-Block elements - (n – 2) f0-14 (n -1) d0-1 ns2 where n is between 6 – 7.
Ques 6. What are representative elements? (1 mark)
Ans. The elements of group 1 (alkali metals), group 2,(alkaline earth metals) and group 13 to group 17 constitute the representative elements. They are also called the s-block and p-block elements.
Ques 7. Give some important characteristics of d block elements? (3 marks)
Ans. Characteristics of d-block elements:
- Shows variable oxidation states
- Their compounds are paramagnetic in nature.
- Most of the d block elements show colour compounds.
- High melting point and boiling points.
Ques 8. Is pure substance an element? (2 marks)
Ans. The single components which can not be divided into various types of substances for example carbon, oxygen, hydrogen, gold, silver and iron are some of the elements. All the elements are made up of only one atom.
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