Reactivity of Metals: Is there a pattern? Name:______

Instructions: Complete this table before the demonstration

Use the following words to fill in the blanks below: (note: you may use a word more than once)
group, electrons, losing, valence electrons, gaining, shells, full, sharing, stable
Atomic number is a key predictor of chemical reactivity of elements because it determines the arrangement of the ______in their shells. Reactivity of elements depends on the number of outer shell electrons called ______. The ______an element is in also tells us how many ______are in its outer shell. Atoms like to have a full outer ______because this is most ______. When reacting to form compounds, atoms end up with ______outer energy levels by ______, ______or ______electrons.

Experiment: Reactivity of Metals

Purpose: To observe the physical and chemical property, and determine the order of metal reactivity within the same and between distinct metal groups.

Observations:

Metal / magnesium / calcium / lithium / sodium / potassium
Symbol
Group
Period
Physical properties
Reaction with water
Observation: During
Reaction with water
Observation: After

Discussion:

1.  Based on experimental evidence, write an answer to the purpose of this experiment.

2. Synthesis

a) Based on observed trends, predict the relative reactivity of each of the following pairs of elements.

Elements / Most reactive of each pair
Li and Fr
Fr and Rb
Cs and Na
Rb and Sr
Ba and Cs

b) What would you expect to observe if cesium were added to water?

Extensions

3. Provide the required information:

Group / 1 / 2 / 17 / 18
Number of valence electrons
How atoms form full outer shell (e.g. gain or lose electrons)

4. Which elements are more reactive? Briefly explain.

a) alkali metals or alkaline earth metals

b) halogens or noble gases

5. Why are group 18 elements stable? Use a B-R diagram to assist your explanation.

6. Is it safe to eat elemental calcium? Explain.
Experiment: Reaction of Alkaline Earth Metals with Water

Purpose: to observe the reactivity of alkaline earth metals with water and to predict the metal reactivity trend within the Periodic Table.

Hypothesis:

Apparatus: test tubes, beaker, test tube holder, Bunsen burner, striker, indicators

Method:

1. Half fill a 400ml beaker with water and invert a test tube filled with water into the beaker. Add two drops of phenolphthalein to the water.

2. Add a piece of calcium metal to the water and observe the reaction.

3. Place about 4 cm of water into a test tube. Heat until the water boils. Add two drops of phenolphthalein to the water , then add a piece of magnesium. Observe.

Observations:

Conclusions:

1. What is the pattern of metal reactivity within the alkaline earth metals?

2. How does this pattern of metal reactivity compare to the alkali metals ?

3. Describe the pattern of metal reactivity that you would expect for all the metals on the Periodic Table.

4. Synthesis

a) Based on observed trends , predict the relative reactivity of each of the following pairs of elements.

elements / Predicted reactivity

Li and Be

Ca and Ba
Cs and Be

b) What would you expect to observe if beryllium were added to water?

5. Write the word equations for the reactions of calcium and magnesium with oxygen and with water.

6. What factors would be responsible for alkali metals being more reactive than alkaline earth metals.

HW: complete this handout and Watch YouTube video: “Alkali Metals: Explosive reactions”