0.5 The best table in the world  (Page 2/3)

Mendeleev arranged the elements in the Periodic Table in order of increasing atomic number in horizontal rows of such length that elements with similar properties recur periodically; that is to say, they fall directly beneath each other in the Table. The elements in a given vertical column are referred to as a family or group. The physical and chemical properties of the elements in a given family change gradually as one goes from one element in the column to the next. By observing the trends in properties, the elements can be arranged in the order in which they appear in the Periodic Table.

Procedure

I. activity series

Part 1. reactions of metals with water

CAUTION! Sodium reacts very rapidly with water to evolve hydrogen and heat. This is potentially dangerous because of the possibility of the violent explosive reaction of $H_2$ (g) with $O_2$ (g) present in the air.

CAUTION! Sodium causes severe chemical burns when it comes into contact with the skin. Note: Metallic sodium must be stored below the surface of an inert liquid such as kerosene to prevent oxidation by air.

• I will demonstrate the reaction of sodium and then potassium with water. Observe the rate of evolution of $H_2$ gas as I use tweezers to place a tiny pea-size piece of sodium then potassium into a 500-mL beaker full of deionised water. Record your observation on the Report Form and write a balanced equation for this reaction.
•  Place 5 mL $H_{2}O$ in each of four clean tubes and label them as follows:

• Use sandpaper or steel wool to remove the oxide from the surfaces of Mg, Cu, and Zn.
• Place several small pieces of Mg, Cu, and Zn in the correctly labeled test tube prepared above. Place two or three (not more!) pieces of Ca turnings in the test tube labeled "Ca".
• Watch for evidence of reaction by noting evolution of gas bubbles and any change in the color or size of the metal. Record your observations and write net ionic equations for each reaction.

 Note: Trapped air bubbles on the metal surfaces are not indicative of a reaction.

CAUTION: $H_2$ is FLAMMABLE!

CAUTION: Residual calcium should be discarded in a special container designated by your instructor.

Note: Net ionic equations must balance in mass (atoms) and in total charge on each side of the equation.

Part 2. reactions of metals with hcl

CAUTION: The reaction of Ca with HCl is not studied. Residual calcium should be discarded in a special container designated by your instructor.

• Decant the water from each test tube used in the procedure above and leave the pieces of metal that remain unreacted in each test tube.
• Place the test tubes in a test tube rack/holder.
• Add 2 mL of 3 M HCl solution to each test tube.

CAUTION: Some of the test tubes may become very hot. Leave them in the rack/holder while you are making observations.

• Observe relative rate of $H_2$ gas evolution for up to 10 minutes and record your observations on your report form.
• Based on the observations in the previous steps, list the elements that react in 3M HCl in order of increasing strength as reducing agents and write net ionic equations for all reactions.