Alkali Metals
Group 1 metals are soft and violently reactive with water.
About this topic
The alkali metals (group 1: Li, Na, K, Rb, Cs, Fr) have a single valence electron. They are soft, shiny, low in density and so reactive they are stored under oil. They react with water to form hydrogen gas and a metal hydroxide, increasing in vigour down the group.
Reactivity rises down the group because the outer electron is further from the nucleus and more shielded, so it is lost more easily. Lithium fizzes steadily in water, sodium darts about and melts, potassium burns with a lilac flame, and rubidium and caesium explode. The equation is 2Na + 2H2O gives 2NaOH + H2. The resulting solution is alkaline, which is how the group got its name. They also form +1 ions and white ionic compounds that dissolve in water.
Sodium chloride seasons food, sodium hydroxide makes soap, potassium is essential for plants and nerves, and lithium is used in rechargeable batteries and in medicine for bipolar disorder. Caesium atoms are used in atomic clocks.
A misconception is that a more reactive metal is a stronger or harder one; the alkali metals can be cut with a knife. Another is that melting and boiling points rise down the group; they fall. Safety is key, so only tiny pieces are used in demonstrations.
Key ideas
- One valence electron
- Reactivity increases down the group
- Stored under oil
Quick check
Use cases: where Alkali Metals helps
- Homework: review the key idea behind Alkali Metals before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Alkali Metals without notes.
- Visual learning: play with the interactive lab to see how Alkali Metals changes when you adjust its inputs.
- Teaching a friend: explain Alkali Metals in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Alkali Metals?
Group 1 metals are soft and violently reactive with water.
What will I learn in Alkali Metals?
One valence electron. Reactivity increases down the group. Stored under oil.
Is Alkali Metals part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Alkali Metals lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Alkali Metals?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
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