Group 1: properties and reactivity
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Summary
Group 1: properties and reactivity
In a nutshell
Group metals have a range of properties. They react with non-metals by forming ionic bonds.
Alkali metals
The elements of Group are called alkali metals because they form alkaline solutions when dissolved in water. Like all metals, they are malleable and can conduct electricity. Group metal ions can be identified by flame tests.
Flame tests are carried out by dipping a clean, nichrome wire into the metal sample and then passing it through a Bunsen burner with a blue flame.
Group metal ION | Flame colour |
| Lithium | Red |
| Sodium | Yellow |
| Potassium | Lilac |
Atomic structure and ionic bonding
Atomic structure
The octet rule specifies that atoms are stable when they have a 'full' outer shell. A full outer shell is equal to eight electrons. Group numbers (columns) in the periodic table tell you how many electrons are in the outer shell of an atom.
A Group metal atom has one electron in its outer shell and are therefore unstable due to an incomplete outer shell.
Ionic bonding
An ionic bond is formed from electrostatic forces of attraction between oppositely charged ions. Group metals become stable by reacting with non-metal elements to form ionic compounds. In doing so, a full outer shell is formed. Group metals lose one electron to form ions. This electron is donated to a non-metal which forms a negative ion. This results in the formation of an ionic bond.
Lithium bromide () forms by ionic bonding. The lithium atom donates an electron to bromine, it then becomes a positively charged ion and bromine becomes a negatively charged bromide ion. Electrostatic forces between these oppositely charged ions allows the ionic compound lithium bromide to form.
Trends in reactivity
Reactivity increases down Group , as the atom size increases down the group. There are therefore more electron shells, so the outer electron is further away from the nucleus as you go down the group. The outer electron is easier to 'lose' because it is less attracted to the nucleus, this increases reactivity down the group.
Reactions
| | Oxygen | Water | Chlorine |
| Lithium | | | |
| Sodium | | | |
| Potassium | | | |
FAQs - Frequently Asked Questions
Are group 1 metals stable?
A group 1 metal atom has one electron in its outer shell and are therefore unstable due to an incomplete outer shell.
What is an ionic bond?
An ionic bond is formed from electrostatic forces of attraction between oppositely charged ions.
How does reactivity change as you go down group 1?
Reactivity increases down group 1, as the atom size increases down the group.
Beta