Groups Flashcards
What happens to the reactivity as you move down GROUP 1
The alkali metals are very reactive
Reactivity INCREASES DOWN THE GROUP
Why does reactivity increase as you move down GROUP 1
LESS ENERGY IS NEEDED TO REMOVE ELECTRONS in the outer most shell because…
atoms get larger so there are more shells of electrons…
so the outer electron is further from the positive nucleus which means…
there is less attraction between the positive nucleus & the outer electron
What is the general equation for when metals in group 1 react with water
Alkali metal + water ———-> alkali metal hydroxide + hydrogen
What is the general balanced equation for the reaction of the alkali metal with water in group 1
2M (s) + 2 H₂O (l) ———-> 2MOH (aq) + H₂(g)
M represents the symbol of any alkali metal
How can we tell that the solution left after reacting a metal with water is alkaline
All metals produce hydrogen when they react with water
The change in colour of the universal indicator shows us that the solution left is alkaline
Describe the electronic configurations of atoms in group 1
They always have one electron in their outer shell
When they react, they lose the electron in the outer shell of their atoms.
The neutral atoms become positive ions.
Describe the electronic configurations of elements in GROUP 0/8
THEY ARE CHEMICALLY INERT - all have full outer shells of electrons and so exist as single atoms as they never need to share electrons
Explain what happens as you go down GROUP 0
The melting point and boiling point both increase and density also increases
List the physical properties of elements in GROUP 7
Diatomic molecules
Strong covalent bonds
Weak intermolecular forces
Low melting and boiling points
Poor conductors of heat and electricity
What pattern is there as you move down GROUP 7
Melting point and boiling point increase
Describe the electronic configurations of elements in GROUP 7
They all have seven electrons in the outer shell, so all want to gain one more electron for a full outer shell
They can do this by either…
Ionic bonding
or
Covalent bonding
What are the group 7 elements known as
Halogens
Why does it become harder to form a negative ion as you move down GROUP 7
The atoms are getting larger as there are more shells of electrons so…
The force of attraction between the positive nucleus and the incoming electron decreases
How do halogens react with hydrogen to form HYDROGEN HALIDES
Example: making hydrochloric acid
Hydrogen and chlorine explode to form hydrogen chloride which dissolves in water to make hydrochloric acid
1. Hydrogen and chloride molecules collide and the covalent bonds holding the atoms together break
2. Covalent bonds form between hydrogen and chloride atoms making a new compound- hydrogen chloride
3. When hydrogen chloride dissolves in water the molecules break up into two ions H+ and Cl-
The formation of H+ ions makes the solution acidic
How does reactivity change as you move down GROUP 7?
They become less reactive
