Alkali and Alkaline Earth Metals

12 Questions

What is the characteristic of alkali metals in terms of ionization energy?

Low ionization energy

Which of the following is a physical property of alkaline earth metals?

Higher density and hardness than alkali metals

What is the product of the reaction between an alkali metal and water?

Alkali metal hydroxide and hydrogen gas

What is the electron configuration of alkaline earth metals?

[noble gas] ns2

Which group of elements has a higher melting and boiling point?

Alkaline earth metals

What is the reaction between an alkali metal and chlorine?

2M + Cl2 → 2MCl

What is the primary reason for the high reactivity of alkali metals?

Low ionization energy

What is the general equation for the reaction of an alkali metal with oxygen?

4M (s) + O2 (g) → 2M2O (s)

What is the product of the reaction between an alkaline earth metal and water?

M(OH)2 (aq) + H2 (g)

What is the general equation for the reaction of an alkali metal with an acid?

2M (s) + 2HCl (aq) → 2MCl (aq) + H2 (g)

What is the product of the reaction between an alkaline earth metal and chlorine?

MCl2 (s)

What is the general equation for the reaction of an alkali metal with nitrogen?

3M (s) + N2 (g) → M3N2 (s)

Study Notes

Alkali Metals

Group 1 elements: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs), Francium (Fr)
Highly reactive, lose one electron to form a positive ion (cation)
Highly electropositive, low ionization energy
Low melting and boiling points, soft and lightweight
React vigorously with water, releasing hydrogen gas

Alkaline Earth Metals

Group 2 elements: Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra)
Less reactive than alkali metals, lose two electrons to form a positive ion (cation)
Less electropositive, higher ionization energy than alkali metals
Higher melting and boiling points, harder and denser than alkali metals
React less vigorously with water, but still release hydrogen gas

Physical Properties

Alkali metals:
- Low density, soft, and lightweight
- High reactivity, react with air and water
- Good conductors of electricity
Alkaline earth metals:
- Higher density, harder, and more dense than alkali metals
- Less reactive, but still react with air and water
- Poorer conductors of electricity than alkali metals

Chemical Reactions

Alkali metals:
- React with water: 2M (alkali metal) + 2H2O → 2MOH (alkali metal hydroxide) + H2
- React with chlorine: 2M (alkali metal) + Cl2 → 2MCl (alkali metal chloride)
Alkaline earth metals:
- React with water: M (alkaline earth metal) + 2H2O → M(OH)2 (alkaline earth metal hydroxide) + H2
- React with chlorine: M (alkaline earth metal) + Cl2 → MCl2 (alkaline earth metal chloride)

Electron Configuration

Alkali metals: [noble gas] ns1 (one electron in outermost energy level)
Alkaline earth metals: [noble gas] ns2 (two electrons in outermost energy level)
Both groups have a full outer energy level, except for the one or two electrons in the s subshell