SC17-19 Flashcards
What are group 1 metals known as?
Alkali metals
Name the elements in group 1?
- Lithium
- Sodium
- Potassium
- Rubidium
- Caesium
- Francium
How many outer electrons do group 1 metals have?
1
Name the physical properties of group 1 metals?
- They have low melting and boiling points (compared with other metals).
- They’re very soft - can be cut with a knife.
How reactive are group 1 metals?
- Very reactive.
- They readily lose their single outer electron to form a 1+ ion with a stable electronic structure.
- The more readily a metal loses it outer electrons, the more reactive it is. So group 1 metals are very reactive.
- As you go down group 1, the alkali metals get more reactive. The outer electron is more easily lost because its further from the nucleus.
So its less strongly attracted to the nucleus and less energy is needed to remove it.
What happens when an alkali metal reacts with water?
They react vigorously
They produce hydrogen gas and a hydroxide of the metal
The reactivity of the metals increases down the group
Lithium will move around on the surface and fizzy.
Sodium and potassium do the same but they also melt in the heat of the reaction
Potassium can even be ignited (lilac flame).
What happens when lithium reacts with water?
It fizzes, floats on the surface and moves around.
What happens when sodium reacts with water?
It floats of the surface, moves around, fizzes and melts into a ball.
What a happens when potassium reacts with water?
It floats on the surface, moves around, fizzes, melts and can ignite with a lilac flame.
What is produced when alkali metals are put in water?
Hydrogen gas.
What are group 7 elements known as?
Halogens
Name the elements in group 7
- Fluorine
- Chlorine
- Bromine
- Iodine
- Astatine
How many outer electrons do group 7 elements have?
7
What are the properties of halogens?
- All diatomic = found in pairs
- Don’t conduct electricity.
- Brittle when solid.
- Poisonous and smelly
Become darker in colour down the group.
What a happens to the melting and boiling points as you go down group 7?
Increases
How can you test for chlorine?
Using damp blue litmus paper
The chlorine will bleach the paper, turning it white.
What are group 7 at room temp?
- chlorine is a fairly reactive, poisonous, green gas
- bromine is a poisonous red-brown liquid, which gives off an orange vapour at room temp.
- iodine is a dark grey crystalline solid which gives off a purple vapour when heated.
What is formed when halogens react with some metals?
They form salts called metal halides.
Explain the reactivity in group 7
- Reactivity decreases going down group 7
- It only needs to gain one electron to form a 1- ion
- It’s harder to attract the extra electron to fill the outer shell when its further away from the nucleus.
What happens when halogens react with metals?
They will react vigorously with some metals to form salts called metal halides.
Halogens higher up in group 7 are more reactive because they can attract the outer electron of the metal more easily.
What is formed when halogens react with hydrogen?
They form hydrogen halides.
What happens when halogens react with hydrogen?
They can form hydrogen halides.
They are soluble and they can dissolve in water to form acidic solutions.
E.g - HCL from hydrochloric acid in water.