Students, in the last video, we learned about physical properties of metals and nonmetals and how these characteristic properties are the basis of many useful inventions in our day-to-day life. Now, in this video, today we are going to learn more about chemical properties of metals and nonmetals. You have learned in previous chapters that electronic configuration is the basis of chemical behavior of elements. In other words, electronic configuration plays a major role in the classification of elements into metals and nonmetals. Let us recall few terms. What is valency? That is right. The number which indicates the ability of an atom to join with another atom with a chemical bond is called as valency of that atom. Majority of metals have up to three electrons in their automotion and metals have a tendency to lose their valence electrons to form positively charged ions that is cations. Sodium. Sodium ion. Sodium atom have one valence electron. It loses one electron. Sodium contains 11 protons, 11 electrons. When it loses one electron, it has 10 electrons and 11 protons. Therefore, it carries one positive charge. In a chemical reaction between sodium and chlorine, sodium atom gives one electron to chlorine atom. Thus, Na plus 1 ion and Cl minus 1 ion are formed simultaneously. As these are oppositely charged, they attract each other forming an acyl molecule. Oxygen atom. 282. Magnesium positive ion. 28. Oxygen. 26. Oxygen. Negative ion. 28. Aluminium. 283. Aluminium positive ion. 28. Nitrogen. 25. Nitrogen. Negative ion. 28. Nitrogen atom has five valence electrons. To complete octet, it accepts three electrons to form anion. Initially, it has seven protons and seven electrons. When it accepts three electrons, it has seven protons and ten electrons. So it carries minus three charge. On the other hand, most of the non-metals have four to seven electrons in their valence shells. Non-metals have a tendency to accept electrons in their valence shell to form negatively charged ions called anions. Now, can you tell me why positive charge is developed in metals and negative charge is developed in non-metals? Inert gases like neon and argon are extremely stable and chemically passive. You understand that if the outermost shell consists of eight electrons, then the atom is stable. But if it is not so less than eight, then what will happen to its reactivity? Observe the following table. Table 1. Metal. Atomic number. Electronic configuration. Sodium. 11. 28. 1. Magnesium. 12. 28. 2. Aluminium. 13. 28. 3. Table 2. Non-metal. Atomic number. Electronic configuration. Nitrogen. 7. 2. 5. Oxygen. 8. 2. 6. Chlorine. 17. 28. 7. What do you see? In the first table, you can see that the electrons in the outermost shell are up to three and the first and second shell have maximum two and eight electrons respectively, which means to maintain the stable state, the atom of the elements have to lose those electrons in the outer shell or to gain electrons to complete the octet. How the atom can decide whether to lose organ electrons? Well, you will learn this in later standards. Similarly, in the second table, you can see that the outermost shell has electrons more than 4 but less than 8. So, they need electrons to complete the octet to attain the stable state. Now consider sodium ion. When sodium atom loses one electron from its outer shell, the octet in the second shell is completed. But the atomic number of sodium is 11, which means its nucleus contains 11 protons, which are positively charged and 11 electrons in the shells, which are negatively charged, before losing the one electron and hence the atom is neutral. After losing the electron in the outer shell, the nucleus still contains 11 protons but there are only 10 electrons left now. Because the sodium ion acquires positive charge, you can see that the charge is directly proportional to the number of electrons lost. The positively charged ions thus formed are called cations. Similarly, consider the element chlorine in this second table. Its atomic number is 17 and it has 7 electrons in its outer shell, which means it needs one electron to complete the octet and attain this stable state. Before receiving this one electron, it is neutral with 17 protons in the nucleus and 17 electrons in the shells. But as this chlorine atom receives or accepts one electron, the number of electrons becomes 18 whereas number of protons in nucleus remain 17. Hence, a negative charge is developed on the chlorine ion thus formed, which are called anions. After the transfer of electrons, both cations and anions obtain inert gas configuration. For example, sodium, magnesium and aluminum ions obtain neon configuration while nitrogen and oxygen ions obtain neon configuration and chlorine ion obtains argon configuration. Now can you explain to your friends the concept of cations and anions formation for the remaining elements in the tables 1 and 2? Interestingly, those who lose electrons are metals and those who gain electrons are non-metals. Thus, we have seen an important chemical property of metals and non-metals. Summary Students, in this video, we discussed about chemical properties of metals and non-metals. We discussed about electronic configuration that forms the basis of chemical behavior of elements. Metals have a tendency to lose their valence electrons to form positively charged ions or cations. Non-metals have a tendency to accept electrons in their valence shell to form negatively charged ions called as anions. Challenge Right cations of metals from group 1 and 2 and anions from non-metals for example, halogen, sulfur, etc.