Predicting and identifying reactions and products Revision Notes

Group 1: Alkali Metals

Group 1 elements, also known as alkali metals, are located on the far left of the periodic table. Key properties include: they are soft metals, have low melting and boiling points (decreasing down the group), and are highly reactive. They all have one electron in their outer shell, which they lose readily to form +1 ions. Reactivity increases as you move down the group (e.g., lithium is less reactive than sodium, which is less reactive than potassium). They react vigorously with water, producing hydrogen gas and an alkaline solution (metal hydroxide). For example, 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g).

Group 7: Halogens

Group 7 elements, or halogens, are found on the right side of the periodic table, just before the noble gases. They are reactive non-metals with seven electrons in their outer shell. They tend to gain one electron to form -1 ions. Their reactivity decreases as you go down the group (e.g., fluorine is more reactive than chlorine, which is more reactive than bromine). Their melting and boiling points increase down the group. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid. Halogens react with metals to form metal halides.

Group 0: Noble Gases

Group 0 elements, the noble gases, are located on the far right of the periodic table. They are characterised by their inertness, meaning they are very unreactive. This is because they have a full outer electron shell (8 electrons, or 2 for helium), making them stable and unwilling to gain, lose, or share electrons. They exist as monatomic gases at room temperature. Their melting and boiling points are very low and increase down the group. Examples include helium, neon, and argon, which are used in applications like balloons, advertising signs, and inert atmospheres for welding.