Alkali Metal Phenomena
Phenomena Background
Notice that the alkali metal atoms (column 1, except hydrogen) are the largest atoms in their row.
Background Knowledge from Last Unit:
The alkali metals are in column 1 of the periodic table (except hydrogen). They are:
Lithium (Li)
Sodium (Na)
Potassium (K)
Rubidium (Rb)
Cesium (Cs)
The atoms before them on the periodic table cannot accept more electrons, so the alkali metals all have one valence electron (outside electron) and therefore are the largest atom in their row.
Alkali Metal Phenomena (New / Better) .mp4Phenomena Introduction
Observations
SOFT METALS: All of the metals are soft (can be cut with a knife) but they get softer as you go down the column (lithium is the hardest, cesium is the softest)
COATING: All of the metals have a coating on the outside. In the same way that iron rusts (combines with oxygen), these metals also combine with oxgyen but their "rust" are different colors. For example:
Lithium's coating is black
Sodium's coating is light gray
This is why all of the metals are stored in oil. Its also the same reason that oil prevents a bike chain from rusting. The oil slows the ability of oxgyen to get to the metals surface
REACTION TO WATER:
All metals produced bubbles when placed in water
In all cases, the reaction to water produces a flammable gas
During the reaction to water, something can be observed coming off of the metals and going into the water to make the water cloudy.
REACTION ENERGY
The reaction with water is more energetic as you go down the column.
Lithium's reaction to water does not generate enough thermal energy to cause the flammable gas to ignite.
Sodium's reaction with water generates enough thermal energy to cause the flammable gas to ignite without an external source of energy (the candle). This is not observed in the video but was in class.
Potassium's reaction with water instantly generates enough thermal energy to ignite the gas produced in the reaction