Page 195 - Chemistry ICSE Class X

Metallurgy 181

How can you predict whether a given element is a metal or
a nonmetal
Metals and nonmetals show characteristic physical and chemical properties.
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the given element is a metal or nonmetal. This is illustrated in Table 7.4.

Table 7.4 To identify whether an element is a metal or a nonmetal
Behaviour of the given element Conclusion
1. Number of electrons in 1, 2 or 3 Metal
the outermost shell 4 to 8 Nonmetal

2. Malleability and ductility Malleable and ductile Metal
Nonmalleable and nonductile, i.e., brittle Nonmetal

3. Conductivity Good conductor of heat and electricity Metal
Nonconductor of heat and electricity. Graphite, however, is the only Nonmetal
nonmetal which is a good conductor of heat and electricity.
4. Nature of oxide Basic oxides that dissolve in water to give an alkaline solution. Such a Metal
solution turns red litmus blue.
Acidic or neutral oxides that dissolve in water to give an acidic Nonmetal
solution. Such a solution turns blue litmus red.
5. Reaction with dilute acids The element reacts with an acid and hydrogen gas is evolved. The less Metal
active metals, however, do not displace hydrogen from acids.
No reaction, i.e., no hydrogen gas is evolved. Nonmetal
6. With hydrogen An ionic hydride is formed. Metal
A covalent hydride is formed. Nonmetal

7. With chlorine An ionic chloride is formed. Metal
A covalent chloride is formed. Nonmetal

Illustrative Questions

Q.1. State which of the following metals would give hydrogen when added to dilute hydrochloric acid:
(a) Iron (b) Copper (c) Magnesium
Ans. Iron and magnesium give hydrogen when added to dilute hydrochloric acid.
Q.2. Name two metals which will displace hydrogen from dilute acids, and two metals which will not displace.
Ans. Metals that will displace hydrogen from dilute acids — Zinc, Magnesium
Metals that will not displace hydrogen from dilute acids — Copper, Silver
Q.3. What type of solution – acidic, basic or neutral, is formed by dissolving the oxides of Group 1 in water?
Ans. The oxides of Group 1 metals when dissolved in water give alkaline (basic) solutions.
Q.4. Name two metals which can form hydrides with hydrogen.
Ans. The metals which form hydrides with hydrogen are
Sodium: sodium gives sodium hydride [NaH(s)]
Calcium: calcium gives calcium hydride [CaH (s)]
2
Q.5. What type of oxides are formed when nonmetals combine with oxygen ?
Ans. Nonmetals when combine with oxygen give neutral or acidic oxides. For example, carbon when combines with
oxygen gives two oxides:
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