C2.4- Groups In the Periodic Table Flashcards
What are the properties of metallic substances?
- Metals are good conductors of heat and electricity
- They have high melting and boiling points.
- Malleable.
- Ductile.
Describe the structure of metals
In a solid metal the atoms are close together and the electron shells overlap. The electrons are free to move in a ‘sea of electrons’ because they are delocalised. The electrons move around randomly but if a voltage is applied the electrons move in one direction.
What makes metals malleable?
The positive ions are arranged in layers, which can slide over each other if enough force is applied. The ion spreads out instead of breaking because the electrons hold the ions together.
What are most metals?
Transition metals. They are found in the middle of the periodic table, have high melting points and form coloured compounds.
Where are the alkali metals found?
They are found in group one of the periodic table.
What are the properties of alkali metals?
- Low melting point compared to other metals.
- They are soft and can be cut with knives.
What do alkali metals react with water to form?
A metal hydroxide and hydrogen gas. For example:
Lithium+water -> lithium hydroxide+hydrogen n
How does reactivity change between the alkali metals?
As you go down the group, the reactivity increases. So lithium is the least reactive and caesium is the most.
Why does reactivity increase as you go down the group of alkali metals?
The elements at the bottom of the group have more electron shells, so they are further from the nucleus. This means that the forces between the positive and negative ions is less because it is greatest when they are close together. The metals react by losing electrons so, the metals with more electrons are more reactive.
Where are the halogens found?
Halogens are found in group 7. They are fluorine, chlorine, bromine and iodine.
Describe each of the halogens at room temperature.
Fluorine- corrosive and a clear gas at room temperature.
Chlorine- a pale yellow gas at room temperature. Also corrosive.
Bromine- poisonous brown gas at room temperature.
Iodine- grey solid at room temperature.
What do halogens react with?
Halogens react with metals to make metal halides.
What charge to do halogen ions have?
-1. They gain an electron to complete their outer shells from metals.
What do halogens form when they react with hydrogen?
Hydrogen halides are formed when halogens dissolve in water.
How does reactivity change within the halogen group?
Fluorine is the most reactive and iodine the least. As you move up the group the halogens get more restive because halogens need to gain electrons. So the fewer shells the stronger the force of attraction, which makes the halogen more reactive.
