periodicity

• mp/bp: decrease as you descend the group because the distance of the delocalised electrons to the nucleus increases, so metallic bond strength decreases • density: generally increases as you descend the group due to the increasing masses of the nuclei • hardness: become softer as you descend the group due to the decreasing strength of metallic bonding • conductivity: good conductors of heat and electricity due to the presence of delocalised electrons

• very reactive as they only have to lose one electron to become stable • the elements have to be stored in oil to prevent them from reacting with oxygen and water in the air • when exposed to the air, the shiny metals will quickly react with oxygen and tarnish, forming metal oxide • descending group 1, the elements become more reactive because less energy is required to remove the electron

lithium: reacts slowly, floats, gradually dissolves, lithium hydroxide formed, H2 given off which burns with a red flame when ignited sodium: reacts more quickly, quickly dissolves, sodium hydroxide formed, H2 given off which burns with a yellow-orange flame when ignited potassium: reacts vigorously, very quickly dissolves, potassium hydroxide formed, H2 given off which burns with a lilac flame when ignited

• high pH as it is alkaline - turns universal indicator blue/purple

• mp/bp increase as you descend the group because there are more electrons so the LDFs are stronger • poor conductors of heat and electricity

• highly reactive as they only need 1 more electron • reactivity decreases as you descend the group because the atoms get larger, so the incoming electron joins a shell that is further from the nucleus -> has a weaker force of attraction to the nucleus

• all colourless at room temp and pressure • very low mp/bp which increase as you descend the group due to more electrons -> stronger LDFs • density increases as you descend the group due to increasing mass of atoms

• very un-reactive because they have a full outer electron shell • therefore, they exist as single atoms (monatomic) • described as being inert (chemically inactive) • some compounds of noble gases at the bottom of the group have been made, e.g. XeF4, KrF2 but only with the most reactive of the non-metal elements

• metal + water -> metal hydroxide + hydrogen