9.1 Properties of Metals, 9.2 Uses of Metals

What are the physical properties of metals?

Thermal & electrical conductor when solid,

Malleable & ductile

High melting point and boiling point.

Note: For all substances, Boiling point > Melting point.

Why do metals conduct electricity?

Metals have metallic bonding in layers with delocalized electrons that can move freely and carry charge —> allows the transfer of electricity.

Note: Non-metals lack metallic bonds and act as insulators. Covalent and ionic bonds do not conduct electricity in the solid state.

Why are copper wires coated in plastic?

Plastic, made from covalent bonds, is an electrical insulator.

—> prevents electricity from escaping and protects objects from the current flowing through copper wires.

How does graphite's atomic structure enable it to conduct electricity?

Graphite has strongly bonded layers separated by delocalized electrons, allowing electrical conductivity.

How does a metal cooking pot demonstrate thermal conductivity?

The pot's metal allows heat to pass through easily to cook food.

Plastic handles are insulators, ensuring the pot can be held safely.

Why do metals have high melting and boiling points?

Requires high energy to overcome metal’s strong intermolecular forces.

Note: Metals remain solid at high temperatures due to these strong forces.

Define malleable and give an example.

Can be easily bent or shaped without breaking.

Example: Gold can be shaped into coins.

Define ductile and give an example.

Being stretched into wires.

Example: Copper wires.

How do non-metals like glass differ from metals in terms of malleability?

Non-metals are brittle, meaning they break easily.

What is the general equation for the reaction of metals with dilute acids?

Metal + acid → salt + hydrogen

Zinc + hydrochloric acid → ?

Zinc + hydrochloric acid → zinc chloride + hydrogen

Zn + 2HCl → ZnCl₂ + H₂

Zinc + sulfuric acid → ?

Zinc + sulfuric acid → Zinc sulfate + hydrogen

Zn + H₂SO₄ → ZnSO₄ + H₂

How can hydrogen gas be tested?

Using the squeaky pop test.

What is the general equation for the reaction of metals with water?

Metal + water → metal hydroxide + hydrogen

Calcium + water → ?. What are the observations?

Calcium + water → calcium hydroxide + hydrogen Ca + 2H₂O → Ca(OH)₂ + H₂.

Observations: Calcium disappears, and hydrogen bubbles form on the metal surface.

How does sodium react with oxygen?

Sodium + oxygen → sodium oxide

4Na + O₂ → 2Na₂O

Why are Group I metals stored in oil?

Group I metals are stored in oil to prevent reactions with oxygen due to their high reactivity.