The periodic table, Year 7: more practice

Metals are good conductors of heat

HintThink about what has to travel from the hob into the food.

The whyHeat passes quickly through a metal base from the hob to the food. A poor conductor such as plastic would stay cool underneath and cook the food slowly.

Iron

HintIts symbol is Fe.

The whyIron, cobalt and nickel are the magnetic metals. Copper, aluminium and gold are not, so magnetism is a useful test for iron but not for metals in general.

Solid

HintThere is just one well-known exception, and it is not the rule.

The whyMost metals have high melting points, so they are solid at room temperature. Mercury is the exception and is a liquid.

Sonorous

HintThink of a bell, a gong or a cymbal.

The whyBells and gongs are made of metal because metals ring when struck. Non-metals such as wood or plastic give a dull thud instead.

It resists being scratched or dented

HintThink about what you could do to its surface with a key.

The whyDiamond is very hard because almost nothing can scratch it. Hard is about the surface, and a hard material can still be brittle.

Strong

HintIt is about how large a force the material can take before it breaks.

The whyA strong material withstands a big force without breaking. Steel is strong, while chalk is easily crushed even though it feels solid.

Flexible

HintThink about what you can do to it without it snapping.

The whyA flexible material bends and returns, or can be bent, without cracking. It is the opposite of brittle, which snaps when you try to bend it.

No, most are poor conductors (insulators)

HintCompare them with copper wire.

The whyNon-metals such as sulfur, oxygen and plastic carbon compounds do not let electricity pass easily. That is why plastic is used to cover wires.

Graphite

HintIt is also a form of carbon, but not the hard, sparkling one.

The whyGraphite is a non-metal that conducts electricity, so it is used in electrodes. It is a famous exception to the rule that non-metals are poor conductors.

It shatters, because solid non-metals are brittle

HintCompare it with how a metal copes with being hammered.

The whySolid non-metals are usually brittle and break into pieces. Metals are malleable and change shape without breaking.