(2.1-2.4C) Lithium, sodium, potassium- Alkali metals

What are alkali metals?

Metals that form alkaline solutions when they react with water.

Where are alkali metals found on the Periodic Table?

In Group 1, the first column

Why do alkali metals share similar characteristic chemical properties?

They all have one electron in their outermost shell.

What does a group 1 metal atom need to lose when it reacts?

One electron, creating a 1+ ion

What are 4 properties shared by the alkali metals?

Soft

Low density

Low melting points

Very reactive

Write a general word equation to show the reaction of group 1 metals with water.

group 1 metal + water → metal hydroxide + hydrogen

What are the observations of the reaction between lithium and water?

• slow

• no melting

• fizzing- seen and heard

What are the observations of the reaction between sodium and water?

• sodium:

  • moves across surface

  • melts

• hydrogen burns

What are the observations of the reaction between potassium and water?

• more violent reaction that sodium

• hydrogen burns with a lilac flame

• melts into a sphere that moves over surface

Name some similarities in the reactions of the first 3 alkali metals with water?

• all fizzed

• all less dense than water (floated)

• relatively low melting points

• all release hydrogen gas

What is produced when alkali metals react with oxygen?

Metal oxides

What is the trend in reactivity as you go down Group 1? Why?

reactivity is stronger as

the size of the atom increases as you go down.

This means the distance between the last shell’s electrons and the nucleus are greater and therefore,

the electrostatic attraction is weaker,

requiring less energy to overcome.

What is the trend of the melting points are you go down Group 1?

lower melting points

decreasing strength of attractive forces between outer electrons and nucleus

easier to overcome bonds

less energy required

Using this, how could the properties of the next elements in Group 1 be predicted?

As you go down:

• reactivity increases

• melting point decreases