Classify each of the following observations as an example of a chemical property.

• Liquid nitrogen boils at -196 °C.

• Propane, leaking from a damaged tank, ignites easily.

• Silver jewellery tarnishes (darkens) in air.

• Spilled oil generally floats on the surface of water.

• Meat darkens when it is heated on a grill.

Classify each of the following observations as an example of a physical property.

• Liquid nitrogen boils at -196 °C.

• Propane, leaking from a damaged tank, ignites easily.

• Silver jewellery tarnishes (darkens) in air.

• Spilled oil generally floats on the surface of water.

• Meat darkens when it is heated on a grill.

Classify each of the following observations as an example of a chemical change.

• Air is often blended into ice cream to give it a lighter texture.

• When popping corn is heated, water inside the kernels becomes a gas and expands. This creates enough pressure to explode the kernel.

• Ethanol is used as an alternative source of energy to power vehicles.

• A loud pop is heard when a lit match is placed at the mouth of a test tube containing hydrogen gas.

• Geothermal energy from underground hot springs is used to heat water to turn turbines and produce electricity.

Classify each of the following observations as an example of a physical change.

• Air is often blended into ice cream to give it a lighter texture.

• When popping corn is heated, water inside the kernels becomes a gas and expands. This creates enough pressure to explode the kernel.

• Ethanol is used as an alternative source of energy to power vehicles.

• A loud pop is heard when a lit match is placed at the mouth of a test tube containing hydrogen gas.

• Geothermal energy from underground hot springs is used to heat water to turn turbines and produce electricity.

Refer to the periodic table to write the symbols for the following elements: K/U (8 marks)

(a) the halogen of the second period

(b) the alkaline earth metal in the fi fth period

(c) the noble gas with the smallest atomic number

(d) the non-metal in the fifth period with seven outermost electrons

(e) the alkali metal of the fourth period

(f) the metal of the third period with three outermost electrons

(g) the unreactive gas of the second period

(h) a non metal that is also liquid at room temperature

• answer

• answer

Refer to the periodic table

• the halogen of the second period

• Cl

• F

• Ar

• O

• I

Refer to the periodic table

the alkaline earth metal in the fifth period

• Sr

• Rb

• K

• Ca

• Br

Refer to the periodic table

the noble gas with the smallest atomic number

• He

• F

• Cl

• H

• O

Refer to the periodic table

the non-metal in the fifth period with seven outermost electrons

• I

• Br

• Kr

• O

• Ca

Refer to the periodic table to

the alkali metal of the fourth period

• Ca

• Sr

• K

• Mg

• H