Name: _____________________________________ Date: _________________
Mr. Sullivan
7th Grade Science
Properties of table salt (NaCl) and the elements which make it up
Directions: Read each passage from a detailed, scientific description of each
substance and answer the corresponding questions in complete sentences.
Properties of Sodium:
 Sodium is a soft, silvery-white metal. It is soft enough to cut with the
edge of a coin.
 Sodium burns in air with a brilliant yellow flame.
 Sodium floats on water, because its density is lower than water’s. It also
reacts vigorously with water – violently if more than a small amount of
sodium meets water.
 Explosions occur when the heat generated by the sodium-water reaction
ignites the resulting hydrogen gas.
Properties of Chlorine:
 Chlorine is a greenish-yellow, dense gas.
 Chlorine has a sharp smell (the smell of bleach).
 It is not found free in nature as it combines readily with nearly all other
elements.
1) Describe three differences between sodium and chlorine.
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Uses of Sodium:
Sodium vapor lamps are highly efficient in producing light
from electricity and are often used for street lighting in
cities.
Sodium is used as a heat transfer agent; for example,
liquid sodium is used to cool nuclear reactors.
Sodium chloride (table salt, NaCl) is vital for good
nutrition. Sodium ions facilitate transmission of electrical
signals in the nervous system and regulate the water
balance between body cells and body fluids.
2) Describe three uses for sodium.
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Uses of Chlorine:
Chlorine is used for producing safe drinking water.
Chlorinated compounds are used mostly for sanitation, pulp
bleaching, disinfectants, and textile processing.
Other uses of chlorine compounds include dyestuffs,
petroleum products, medicines, antiseptics, insecticides,
foodstuffs, solvents, paints and plastics.
Exposure to small amounts of chlorine, even for a short
time, can be deadly.
Chlorine is heavier than air. When released, it forms a
poisonous blanket that drifts along with the wind. Chlorine
was used as a chemical weapon in World War I, first in
1915 by the German army and then by the Western Allies.
3) Describe three uses for chlorine.
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Uses of table salt:
Sodium chloride—also known as table salt—is necessary to help your body maintain
fluid balance, help your muscles relax and your nerves transmit signals. Sodium
chloride also helps maintain normal blood pressure. One of salt’s earliest roles was to
preserve food (it does this by drawing out water, preventing bacteria from growing).
4) What are three uses for table salt.
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5) Based on your answers to the previous questions, describe two ways in which sodium
is different from table salt.
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6) Based on your answers to the previous questions, describe two ways in which
chlorine is different from table salt.
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