Year 7 Science Unit 5.3 Metals and Alloys

Which of the following demonstrates a property of a metal?

• Malleable

• Dull

• Brittle

• None of these

Answer explanation

Malleability is a key property of metals, allowing them to be hammered or rolled into thin sheets without breaking. In contrast, dullness and brittleness are not characteristic of metals, making 'malleable' the correct choice.

If you have a material that can conduct electricity well it is probably a...

• Metalloid

• Matter

• Non-metal

• Metal

Answer explanation

A material that conducts electricity well is typically a metal. Metals have free electrons that allow them to easily transfer electric current, unlike non-metals and metalloids, which are generally poor conductors.

I have an object that is dull, brittle, and an insulator, what is it?

• metalloid

• non-metal

• metal

• matter

Answer explanation

The object is dull, brittle, and an insulator, which are typical properties of non-metals. Non-metals are generally poor conductors of heat and electricity, unlike metals, making 'non-metal' the correct choice.

What physical properties classify elements as metals, non-metals, or metalloids?

• Color, smell, physical state

• Reactivity, streak, hardness

• Ability to burn, mass, density

• Luster, conductivity, malleability

Answer explanation

Elements are classified based on their physical properties. Metals typically have luster, high conductivity, and malleability, while non-metals do not. Thus, luster, conductivity, and malleability are key properties for this classification.

Which of the following would help a student classify an unknown element as a metal, metalloid, or non-metal?

• Measure its conductivity

• Determine its density

• Find its melting point

• Observe its color

Answer explanation

Measuring conductivity is key to classifying elements. Metals conduct electricity well, non-metals do not, and metalloids have intermediate conductivity. This property directly indicates the element's category.

Non-metals are good conductors of heat and electricity. 

• TRUE

• FALSE

Answer explanation

Non-metals are generally poor conductors of heat and electricity. Materials like metals are known for their conductivity, while non-metals, such as sulfur and phosphorus, do not conduct heat and electricity well. Therefore, the statement is FALSE.

Metals are ductile, meaning they can be drawn into wire

• True

• False

• Never

Answer explanation

True. Metals are indeed ductile, which means they can be stretched and drawn into wires without breaking, making this statement correct.

Unlike non-metals, most metals tend to —

• conduct electricity and heat well.

• be gases at room temperature.

• break easily when hammered.

• have less luster and shine.

Answer explanation

Unlike non-metals, most metals are good conductors of electricity and heat due to their free-moving electrons. This property distinguishes them from non-metals, which typically do not conduct electricity or heat well.

Luster is ___________

• A.  the way light is reflected off a surface.

• A.  how well a piece of matter conducts electricity. 

• A.  the capability of being drawn out into thin wires or threads.

• A.  the capability of being hammered out thin.

Answer explanation

Luster refers to the way light is reflected off a surface, which is why the correct answer is the first choice. The other options describe different physical properties, not related to luster.

Which could be a correct symbol for a chemical element?

• Ca

• n

• CO

• Alu

Answer explanation

The correct symbol for a chemical element must consist of one or two letters, with the first letter capitalized. 'Ca' is the symbol for calcium, while 'n', 'CO', and 'Alu' do not meet the criteria.