alkali metals group 1 Flashcards
(18 cards)
What are the Group 1 metals known as?
Alkali metals
The Group 1 metals include lithium, sodium, potassium, rubidium, caesium, and francium.
What do Group 1 metals form when they react with water?
Alkaline solutions
These reactions produce metal hydroxides and hydrogen gas.
What is the general formula for the reaction of a Group 1 metal with water?
2M (s) + 2H2O (l) ⟶ 2MOH (aq) + H2 (g)
M represents Li, Na, K, Rb, or Cs.
What are the physical properties of alkali metals?
Soft, low densities, low melting points
They can be easily cut with a knife.
How does the reactivity of alkali metals change as you go down the group?
Increases
The reactions with water become more vigorous.
What observation is made when lithium reacts with water?
Fizzing and moves on the surface
The reaction is relatively slow.
What happens when sodium reacts with water?
More vigorous fizzing, moves rapidly, dissolves quickly
Sodium produces sodium hydroxide and hydrogen.
What is produced when potassium reacts with oxygen?
Potassium oxide
The reaction produces a dull coating on the metal.
What is the trend in melting points of Group 1 metals as you descend the group?
Decreases
This is due to decreasing attractive forces between outer electrons and positive ions.
what do alkali metals that react with the air form
Metal oxides
What is the reactivity order of alkali metals from least to most reactive?
Lithium < Sodium < Potassium < Rubidium < Caesium < Francium
Francium is the most reactive alkali metal.
What characteristic do all alkali metals share regarding their outermost electron?
One electron
This contributes to their similar chemical properties.
True or False: The first three alkali metals are more dense than water.
False
They are less dense than water.
What can be predicted about rubidium based on its position in Group 1?
Reacts more vigorously with air and water than potassium
It is expected to be a soft grey solid that appears shiny when freshly cut.
What type of solution do alkali metals form when reacting with water?
Colourless aqueous solutions
The hydroxides formed are all similar in nature.
What visual indication is observed during the reaction of potassium with water?
Burns with a lilac flame
This indicates a vigorous reaction.
what gas is produced
hydrogen gas
observations
floats if denser than water
melts into ball because melting point is low
fizzing, indicating hydrogen gas formation
moves around surface
piece gets smaller and disappears eventually
