Metals - Physical Properties

1. METALS

3. Atoms, Elements and Compounds Difference between Metals and Non-metals METALS Chemical Bonding: The Structure of Matter Metallic Bonding Acids and Bases Reactions of metals with acids Reactions of metal oxides and hydroxides Preparation Of Salt Reacting an acid with a metal The Periodic Table Alkali metals Transition metals Links between the chapter on metals and other chapters. Flow chart 2:

5. Good conductor of Heat Good conductor of Electricity Sonorous Can you think of what are some of the other physical properties of metals? What important property of metals is evident in each picture?

6. Can be bend and stretched without breaking Malleable and ductile Ease of Shaping Strong and tough Strength Usually high Density Solid (EXCEPT mercury, which is a liquid Physical State Usually high (except mercury and alkali metals) Melting and Boiling Point Shiny surfaces Appearance Metals Property Worksheet 1: Physical properties of Metals

7. Mercury Metal The element MERCURY (Hg) is the only metal which is liquid at room temperature! Melting Point (°C) -38.87 Boiling Point (°C) 356.9

9. Strong forces of attraction between the ‘sea of negatively charged electrons’ and the positive metal ions. High melting and boiling points Presence of free electrons carries heat and electricity energy. Good conductor of heat and electricity (in solid or molten state) Layers of metal atoms can slide over each other without disrupting the metallic bonding. Hence, metallic bonds are strong and flexible. Malleable (hammered into sheets) and Ductile (drawn into wires) without breaking Reason(s) Physical Properties The structure of Metal Push

10. Give three reasons why tungsten is used to make the filament inside an electric bulb? Reasons: (1) Tungsten can be drawn into very thin metal wires. (2) Tungsten has the highest melting point (3422 °C). (3) Tungsten has strong resistance to high temperature. Quick Wits

12. Over three quarter of the Periodic Table is made up of metals. Metals are useful materials in our everyday lives, from window grills to cooking pots and cars to other means of transport. Metals are undeniably important to us!

13. What do you think the objects in each picture are made of? Pure Gold? Pure Copper? Pure Iron? Pure metals have many useful properties but are not widely used. They are often too soft and have a low resistance to corrosion WHY?

14. How to make pure metals stronger and harder so that we can use them in our daily lives? By mixing two or more pure metals together Alloy - A mixture of a metal with another element. Metal + Metal Metal + Carbon (Non-metal) Alloy OR - Are made by mixing the molten elements (metals or carbon) in the right proportion and allowing them to solidify. Question

15. Join metals Solder 50% tin and 50% lead Trophies Bronze Copper and Tin Surgical instruments, window grills etc. Stainless steel 73% iron, 18% chromium, 8% nickel and 1% carbon Ornaments and souvenirs etc Pewter 97% tin, antimony (Sb) and copper Musical Instruments etc Brass 70% copper and 30% zinc Uses of Alloys Alloys Metals Examples and Uses of Alloys

16. Four main reasons for making alloys To improve the strength and hardness of metals. To improve the resistance of metals against corrosion and rusting. To improve the appearance of the metal. To lower the melting point of the metal.

17. Different-sized atoms Key: Pure metal atom Foreign atom (May be metal or non-metal Thinking Question 1: “ The physical properties of alloys are different from those of the elements they contain”. Give two examples to illustrate the statement. The structure of Alloys

19. Remark : It is more difficult to rearrange the atoms in an alloy. Remark: It is easy to rearrange the atoms in a pure metal. Structure of Alloys Structure of Pure metals Recall… Thinking Question 2: Explain why an alloy is less malleable than the pure metal. Different- sized atoms Large Push Push

20. Thinking Question 2: Explain why an alloy is less malleable than the pure metal. Hint: Recall how the atoms are arranged in the structure of pure metals and alloys. Alloys are strong and hard, not easily bent. Layers of atoms cannot slide over each other easily as foreign atoms are of different sizes and disrupt the orderly arrangement of metal atoms. Pure metals are soft and easily bent (malleable) because layers of atoms (of the same size) can slide over each other easily. This sliding movement of atoms is called a slip . Alloys Pure metals Solution: Malleable Can be beaten into thin sheets without breaking.